AD4001BRMZ-RL7 [ADI]

Precision, Differential SAR ADCs;
AD4001BRMZ-RL7
型号: AD4001BRMZ-RL7
厂家: ADI    ADI
描述:

Precision, Differential SAR ADCs

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16-Bit, 2 MSPS/1 MSPS,  
Precision, Differential SAR ADCs  
Data Sheet  
AD4001/AD4005  
FEATURES  
GENERAL DESCRIPTION  
The AD4001/AD4005 are low noise, low power, high speed, 16-bit,  
precision successive approximation register (SAR) analog-to-digital  
converters (ADCs). The AD4001 offers a 2 MSPS throughput, and  
the AD4005 offers a 1 MSPS throughput. They incorporate ease  
of use features that reduce signal chain power consumption,  
reduce signal chain complexity, and enable higher channel density.  
The high-Z mode, coupled with a long acquisition phase,  
eliminates the need for a dedicated high power, high speed  
ADC driver, thus broadening the range of low power precision  
amplifiers that can drive these ADCs directly, while still achieving  
optimum performance. The input span compression feature  
enables the ADC driver amplifier and the ADC to operate off  
common supply rails without the need for a negative supply while  
preserving the full ADC code range. The low serial peripheral  
interface (SPI) clock rate requirement reduces the digital  
input/output power consumption, broadens processor options,  
and simplifies the task of sending data across digital isolation.  
Throughput: 2 MSPS/1 MSPS options  
INL: 0.4 LSB maximum  
Guaranteed 16-bit no missing codes  
Low power  
9.5 mW at 2 MSPS, 4.9 mW at 1 MSPS (VDD only)  
80 μW at 10 kSPS, 16 mW at 2 MSPS (total)  
SNR: 96.2 dB typical at 1 kHz, VREF = 5 V; 95.5 dB typical at 100 kHz  
THD: −123 dB typical at 1 kHz, VREF = 5 V; −99 dB typical at 100 kHz  
Ease of use features reduce system power and complexity  
Input overvoltage clamp circuit  
Reduced nonlinear input charge kickback  
High-Z mode  
Long acquisition phase  
Input span compression  
Fast conversion time allows low SPI clock rates  
SPI-programmable modes, read/write capability, status word  
Differential analog input range: VREF  
0 V to VREF with VREF from 2.4 V to 5.1 V  
Operating from a 1.8 V supply, the AD4001/AD4005 have a VREF  
fully differential input range with VREF ranging from 2.4 V to 5.1 V.  
The AD4001 consumes only 16 mW at 2 MSPS with a minimum  
SCK rate of 70 MHz in turbo mode, and the AD4005 consumes  
only 8 mW at 1 MSPS. The AD4001/AD4005 both achieve  
0.4 LSB integral nonlinearity error (INL) maximum, guaranteed  
no missing codes at 16 bits with 96.2 dB typical signal-to-noise  
ratio (SNR) for 1 kHz inputs. The reference voltage is applied  
externally and can be set independently of the supply voltage.  
Single 1.8 V supply operation with 1.71 V to 5.5 V logic interface  
SAR architecture: no latency/pipeline delay, valid first conversion  
First accurate conversion  
Guaranteed operation: −40°C to +125°C  
SPI-/QSPI-/MICROWIRE-/DSP-compatible serial interface  
Ability to daisy-chain multiple ADCs and busy indicator  
10-lead packages: 3 mm × 3 mm LFCSP, 3 mm × 4.90 mm MSOP  
APPLICATIONS  
Automatic test equipment  
Machine automation  
Medical equipment  
Battery-powered equipment  
Precision data acquisition systems  
The SPI-compatible, versatile serial interface features seven  
different modes including the ability, using the SDI input, to  
daisy-chain several ADCs on a single 3-wire bus, and provides an  
optional busy indicator. The AD4001/AD4005 are compatible with  
1.8 V, 2.5 V, 3 V, and 5 V logic, using the separate VIO supply.  
The AD4001/AD4005 are available in a 10-lead MSOP or LFCSP  
with operation specified from −40°C to +125°C. The devices are  
pin compatible with the 18-bit, 2 MSPS AD4003 (see Table 8).  
FUNCTIONAL BLOCK DIAGRAM  
2.4V TO 5.1V  
10µF  
1.8V  
REF  
VDD  
VIO  
SDI  
AD4001/  
AD4005  
1.8V TO 5V  
V
REF  
/2  
0
HIGH-Z  
MODE  
TURBO  
MODE  
V
V
REF  
IN+  
IN–  
SCK  
3-WIRE OR 4-WIRE  
SPI INTERFACE  
(DAISY CHAIN, CS)  
SERIAL  
INTERFACE  
16-BIT  
SAR ADC  
SDO  
CNV  
V
REF  
/2  
STATUS  
BITS  
SPAN  
COMPRESSION  
CLAMP  
REF  
0
GND  
Figure 1.  
Rev. B  
Document Feedback  
Information furnished by Analog Devices is believed to be accurate and reliable. However, no  
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other  
rights of third parties that may result from its use. Specifications subject to change without notice. No  
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.  
Trademarks and registered trademarks are the property of their respective owners  
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.  
Tel: 781.329.4700  
Technical Support  
©2017 Analog Devices, Inc. All rights reserved.  
www.analog.com  
 
 
 
 
AD4001/AD4005  
Data Sheet  
TABLE OF CONTENTS  
Features .............................................................................................. 1  
Analog Inputs ............................................................................. 20  
Driver Amplifier Choice ........................................................... 22  
Ease of Drive Features ............................................................... 23  
Voltage Reference Input ............................................................ 24  
Power Supply............................................................................... 24  
Digital Interface.......................................................................... 25  
Register Read/Write Functionality........................................... 26  
Status Word ................................................................................. 28  
Applications....................................................................................... 1  
General Description......................................................................... 1  
Functional Block Diagram .............................................................. 1  
Revision History ............................................................................... 2  
Specifications..................................................................................... 4  
Timing Specifications .................................................................. 7  
Absolute Maximum Ratings............................................................ 9  
Thermal Resistance ...................................................................... 9  
ESD Caution.................................................................................. 9  
Pin Configurations and Function Descriptions ......................... 10  
Typical Performance Characteristics ........................................... 11  
Terminology .................................................................................... 16  
Theory of Operation ...................................................................... 17  
Circuit Information.................................................................... 17  
Converter Operation.................................................................. 18  
Transfer Functions...................................................................... 18  
Applications Information .............................................................. 19  
Typical Application Diagrams .................................................. 19  
CS  
CS  
CS  
CS  
CS  
CS  
Mode, 3-Wire Turbo Mode ................................................. 29  
Mode, 3-Wire Without Busy Indicator ............................. 30  
Mode, 3-Wire with Busy Indicator .................................... 31  
Mode, 4-Wire Turbo Mode ................................................. 32  
Mode, 4-Wire Without Busy Indicator ............................. 33  
Mode, 4-Wire with Busy Indicator .................................... 34  
Daisy-Chain Mode..................................................................... 35  
Layout Guidelines....................................................................... 36  
Evaluating the AD4001/AD4005 Performance.......................... 36  
Outline Dimensions....................................................................... 37  
Ordering Guide .......................................................................... 37  
REVISION HISTORY  
8/2017—Rev. A to Rev. B  
CS  
Mode, 4-Wire Turbo Mode Section and  
Changes to  
Figure 58 .......................................................................................... 32  
CS  
Changes to General Description Section ...................................... 1  
Changes to Table 1............................................................................ 6  
Changes to Endnote 3, Table 2 ........................................................ 7  
Changes to Table 4............................................................................ 8  
Change to Pin 3 Description and Pin 4 Description, Table 7... 10  
Reorganized Typical Performance Characteristics Section ...... 13  
Changes to Figure 17, Figure 19, and Figure 21 ......................... 13  
Added Figure 23; Renumbered Sequentially .............................. 14  
Changes to Figure 27...................................................................... 15  
Changes to Circuit Information Section and Table 8 ................ 17  
Changes to Endnote 1 and Endnote 2, Table 9 ........................... 18  
Changes to Figure 37 Caption and RC Filter Values Section ... 21  
Changes to High Frequency Input Signals Section, Figure 38  
Caption, and Figure 39 Caption ................................................... 22  
Added Multiplexed Applications Section and Figure 40........... 22  
Changes to Figure 41 and Figure 42 Caption ............................. 23  
Changes to Figure 43, Figure 44 Caption, Figure 45, and Voltage  
Reference Input Section................................................................. 24  
Changes to Power Supply Section, Figure 46, Figure 47, Digital  
Interface Section, and Table 11..................................................... 25  
Changes to  
Mode, 4-Wire with Busy Indicator Section and  
Figure 62 .......................................................................................... 34  
4/2017—Rev. 0 to Rev. A  
Added AD4005 ...................................................................Universal  
Changes to Title, Features Section, General Description Section,  
and Figure 1........................................................................................1  
Changes to Table 1.............................................................................3  
Changes to Table 2.............................................................................6  
Changes to Table 4.............................................................................7  
Changes to Figure 19 Caption and Figure 21 ............................. 12  
Changes to Figure 24...................................................................... 13  
Added Figure 25; Renumbered Sequentially .............................. 13  
Changes to Circuit Information Section and Table 8................ 16  
Changes to RC Filter Values Section............................................ 20  
Changes to High Frequency Input Signals Section.................... 21  
Changes to High-Z Mode Section and Figure 41....................... 22  
Changes to Long Acquisition Phase Section .............................. 23  
Changes to Digital Interface Section and Register Read/Write  
Functionality Section..................................................................... 24  
CS  
Changes to  
Mode, 3-Wire Turbo Mode Section................... 29  
CS  
Changes to  
Mode, 3-Wire with Busy Induction Section and  
CS  
CS  
Changes to  
Changes to  
Mode, 3-Wire Turbo Mode Section .................. 27  
Mode, 4-Wire Turbo Mode Section .................. 30  
Figure 56 .......................................................................................... 31  
Rev. B | Page 2 of 37  
 
Data Sheet  
AD4001/AD4005  
Changes to Layout Guidelines Section and Evaluating the  
AD4001/AD4005 Performance Section.......................................34  
Updated Outline Dimensions........................................................35  
Changes to Ordering Guide...........................................................35  
1/2017—Revision 0: Initial Version  
Rev. B | Page 3 of 37  
AD4001/AD4005  
SPECIFICATIONS  
Data Sheet  
VDD = 1.71 V to 1.89 V, VIO = 1.71 V to 5.5 V, VREF = 5 V, all specifications TMIN to TMAX, high-Z mode disabled, span compression disabled,  
turbo mode enabled, and sampling frequency (fS) = 2 MSPS for the AD4001 and fS = 1 MSPS for the AD4005, unless otherwise noted.  
Table 1.  
Parameter  
Test Conditions/Comments  
Min  
Typ  
Max  
Unit  
RESOLUTION  
ANALOG INPUT  
Voltage Range  
16  
Bits  
VIN+ − VIN−  
−VREF  
+VREF  
V
Span compression enabled  
VIN+, VIN− to GND  
Span compression enabled  
−VREF × 0.8  
−0.1  
0.1 × VREF  
+VREF × 0.8  
VREF + 0.1  
0.9 × VREF  
VREF/2 + 0.125  
V
V
V
V
dB  
nA  
µA  
Operating Input Voltage  
Common-Mode Input Range  
Common-Mode Rejection Ratio (CMRR)  
Analog Input Current  
VREF/2 − 0.125 VREF/2  
fIN = 500 kHz  
Acquisition phase, T = 25°C  
High-Z mode enabled, converting  
dc input at 2 MSPS  
68  
0.3  
1
THROUGHPUT  
Complete Cycle  
AD4001  
AD4005  
Conversion Time  
Acquisition Phase1  
AD4001  
500  
1000  
ns  
ns  
ns  
290  
320  
290  
790  
ns  
ns  
AD4005  
Throughput Rate2  
AD4001  
AD4005  
Transient Response3  
0
0
2
1
MSPS  
MSPS  
ns  
250  
DC ACCURACY  
No Missing Codes  
Integral Nonlinearity Error (INL)  
Differential Nonlinearity Error (DNL)  
Transition Noise  
Zero Error  
16  
−0.4  
−0.5  
Bits  
LSB  
LSB  
LSB  
LSB  
ppm/°C  
LSB  
ppm/°C  
LSB  
µV p-p  
0.2  
0.2  
0.35  
0.1  
+0.4  
+0.5  
−1.5  
+1.5  
Zero Error Drift4  
−0.28  
−16.5  
−0.23  
+0.28  
+16.5  
+0.23  
Gain Error  
Gain Error Drift4  
Power Supply Sensitivity  
1/f Noise5  
0.4  
VDD = 1.8 V 5%  
Bandwidth = 0.1 Hz to 10 Hz  
0.25  
6
AC ACCURACY  
Dynamic Range  
96.3  
54  
dB  
µV rms  
Total RMS Noise  
fIN = 1 kHz, −0.5 dBFS, VREF = 5 V  
Signal-to-Noise Ratio (SNR)  
Spurious-Free Dynamic Range (SFDR)  
Total Harmonic Distortion (THD)  
95.6  
95.5  
96.2  
122  
−123  
96  
dB  
dB  
dB  
dB  
Signal-to-Noise-and-Distortion Ratio  
(SINAD)  
Oversampled Dynamic Range  
Oversampling ratio (OSR) = 256,  
VREF = 5 V  
120  
dB  
Rev. B | Page 4 of 37  
 
 
Data Sheet  
AD4001/AD4005  
Parameter  
Test Conditions/Comments  
Min  
Typ  
Max  
Unit  
fIN = 1 kHz, −0.5 dBFS, VREF = 2.5 V  
SNR  
SFDR  
THD  
SINAD  
92.1  
93.2  
118  
−117  
93  
dB  
dB  
dB  
dB  
92  
fIN = 100 kHz, −0.5 dBFS, VREF = 5 V  
SNR  
THD  
SINAD  
95.5  
−99  
93.8  
dB  
dB  
dB  
fIN = 400 kHz, −0.5 dBFS, VREF = 5 V  
SNR  
THD  
91  
−92  
89  
10  
1
dB  
dB  
dB  
MHz  
ns  
SINAD  
−3 dB Input Bandwidth  
Aperture Delay  
Aperture Jitter  
REFERENCE  
1
ps rms  
Voltage Range, VREF  
Current  
AD4001  
2.4  
5.1  
V
VREF = 5 V  
2 MSPS  
1 MSPS  
1.1  
0.5  
mA  
mA  
AD4005  
INPUT OVERVOLTAGE CLAMP  
IN+/IN− Current, IIN+/IIN−  
VREF = 5 V  
VREF = 2.5 V  
VREF = 5 V  
VREF = 2.5 V  
VREF = 5 V  
VREF = 2.5 V  
50  
50  
mA  
mA  
V
V
V
V
ns  
µA  
VIN+/VIN− at Maximum IIN+/IIN−  
5.4  
3.1  
5.4  
2.8  
360  
100  
VIN+/VIN− Clamp On/Off Threshold  
5.25  
2.68  
Deactivation Time  
REF Current at Maximum IIN+/IIN−  
DIGITAL INPUTS  
VIN+/VIN− > VREF  
Logic Levels  
Input Low Voltage, VIL  
VIO > 2.7 V  
VIO ≤ 2.7 V  
VIO > 2.7 V  
VIO ≤ 2.7 V  
−0.3  
−0.3  
0.7 × VIO  
0.8 × VIO  
−1  
+0.3 × VIO  
+0.2 × VIO  
VIO + 0.3  
VIO + 0.3  
+1  
V
V
V
V
µA  
µA  
pF  
Input High Voltage, VIH  
Input Low Current, IIL  
Input High Current, IIH  
Input Pin Capacitance  
DIGITAL OUTPUTS  
Data Format  
−1  
+1  
6
Serial 16 bits, twos complement  
Pipeline Delay  
Conversion results available immediately  
after completed conversion  
Output Low Voltage, VOL  
Output High Voltage, VOH  
POWER SUPPLIES  
VDD  
ISINK = 500 µA  
ISOURCE = −500 µA  
0.4  
V
V
VIO − 0.3  
1.71  
1.71  
1.8  
1.6  
1.89  
5.5  
V
V
µA  
VIO  
Standby Current  
VDD = 1.8 V, VIO = 1.8 V, T = 25°C  
Rev. B | Page 5 of 37  
AD4001/AD4005  
Data Sheet  
Parameter  
Test Conditions/Comments  
VDD = 1.8 V, VIO = 1.8 V, VREF = 5 V  
10 kSPS, high-Z mode disabled  
1 MSPS, high-Z mode disabled  
2 MSPS, high-Z mode disabled  
1 MSPS, high-Z mode enabled  
2 MSPS, high-Z mode enabled  
1 MSPS, high-Z mode disabled  
2 MSPS, high-Z mode disabled  
1 MSPS, high-Z mode disabled  
2 MSPS, high-Z mode disabled  
1 MSPS, high-Z mode disabled  
2 MSPS, high-Z mode disabled  
Min  
Typ  
Max  
Unit  
Power Dissipation  
80  
8
µW  
mW  
mW  
mW  
mW  
mW  
mW  
mW  
mW  
mW  
mW  
nJ/sample  
9.3  
16  
10  
20  
4.9  
9.5  
2.8  
5.5  
0.4  
1.0  
8
18.5  
12.3  
24.5  
VDD Only  
REF Only  
VIO Only  
Energy per Conversion  
TEMPERATURE RANGE  
Specified Performance  
TMIN to TMAX  
−40  
+125  
°C  
1 The acquisition phase is the time available for the input sampling capacitors to acquire a new input with the ADC running at a throughput rate of 2 MSPS for the  
AD4001 and 1 MSPS for the AD4005.  
2 A throughput rate of 2 MSPS can only be achieved with turbo mode enabled and a minimum SCK rate of 70 MHz. Refer to Table 4 for the maximum achievable  
throughput for different modes of operation.  
3 Transient response is the time required for the ADC to acquire a full-scale input step to 1 LSB accuracy.  
4 The minimum and maximum values are guaranteed by characterization, but not production tested.  
5 See the 1/f noise plot in Figure 23.  
Rev. B | Page 6 of 37  
 
 
 
 
 
Data Sheet  
AD4001/AD4005  
TIMING SPECIFICATIONS  
VDD = 1.71 V to 1.89 V, VIO = 1.71 V to 5.5 V, VREF = 5 V, all specifications TMIN to TMAX, high-Z mode disabled, span compression  
disabled, turbo mode enabled, and sampling frequency (fS) = 2 MSPS for the AD4001 and fS = 1 MSPS for the AD4005, unless otherwise  
noted. See Figure 2 for the timing voltage levels.  
Table 2. Digital Interface Timing  
Parameter  
Symbol  
tCONV  
Min  
Typ  
Max  
Unit  
CONVERSION TIME—CNV RISING EDGE TO DATA AVAILABLE  
270  
290  
320  
ns  
ACQUISITION PHASE1  
tACQ  
AD4001  
AD4005  
290  
790  
ns  
ns  
TIME BETWEEN CONVERSIONS  
AD4001  
AD4005  
CNV PULSE WIDTH (CS MODE)2  
SCK PERIOD (CS MODE)3  
tCYC  
500  
1000  
10  
ns  
ns  
ns  
tCNVH  
tSCK  
VIO > 2.7 V  
VIO > 1.7 V  
9.8  
12.3  
ns  
ns  
SCK PERIOD (DAISY-CHAIN MODE)4  
tSCK  
VIO > 2.7 V  
VIO > 1.7 V  
20  
25  
3
ns  
ns  
ns  
ns  
ns  
SCK LOW TIME  
tSCKL  
tSCKH  
tHSDO  
tDSDO  
SCK HIGH TIME  
3
SCK FALLING EDGE TO DATA REMAINS VALID DELAY  
1.5  
SCK FALLING EDGE TO DATA VALID DELAY  
VIO > 2.7 V  
VIO > 1.7 V  
7.5  
10.5  
ns  
ns  
CNV OR SDI LOW TO SDO D15 MOST SIGNIFICANT BIT (MSB) VALID DELAY (CS MODE)  
VIO > 2.7 V  
tEN  
10  
13  
ns  
ns  
ns  
ns  
ns  
VIO > 1.7 V  
CNV RISING EDGE TO FIRST SCK RISING EDGE DELAY  
LAST SCK FALLING EDGE TO CNV RISING EDGE DELAY5  
CNV OR SDI HIGH OR LAST SCK FALLING EDGE TO SDO HIGH IMPEDANCE (CS MODE)  
tQUIET1  
tQUIET2  
tDIS  
190  
60  
20  
SDI VALID SETUP TIME FROM CNV RISING EDGE  
tSSDICNV  
tHSDICNV  
tHSCKCNV  
tSSDISCK  
tHSDISCK  
2
ns  
ns  
ns  
ns  
ns  
SDI VALID HOLD TIME FROM CNV RISING EDGE (CS MODE)  
SCK VALID HOLD TIME FROM CNV RISING EDGE (DAISY-CHAIN MODE)  
SDI VALID SETUP TIME FROM SCK RISING EDGE (DAISY-CHAIN MODE)  
SDI VALID HOLD TIME FROM SCK RISING EDGE (DAISY-CHAIN MODE)  
2
12  
2
2
1 The acquisition phase is the time available for the input sampling capacitors to acquire a new input with the ADC running at a throughput rate of 2 MSPS for the  
AD4001 and 1 MSPS for the AD4005.  
2 For turbo mode, tCNVH must match the tQUIET1 minimum.  
3 A throughput rate of 2 MSPS can only be achieved with turbo mode enabled and a minimum SCK rate of 70 MHz. Refer to Table 4 for the maximum achievable  
throughput for different modes of operation.  
4 A 50% duty cycle is assumed for SCK.  
5 See Figure 22 for SINAD vs. tQUIET2  
.
1
Y% VIO  
1
X% VIO  
tDELAY  
tDELAY  
2
2
V
V
V
IH  
IH  
2
2
V
IL  
IL  
1
2
FOR VIO ≤ 2.7V, X = 80, AND Y = 20; FOR VIO > 2.7V, X = 70, AND Y = 30.  
MINIMUM V AND MAXIMUM V USED. SEE DIGITAL INPUTS  
IH  
IL  
SPECIFICATIONS IN TABLE 1.  
Figure 2. Voltage Levels for Timing  
Rev. B | Page 7 of 37  
 
 
 
 
 
AD4001/AD4005  
Data Sheet  
Table 3. Register Read/Write Timing  
Parameter  
Symbol  
Min  
Typ  
Max  
Unit  
READ/WRITE OPERATION  
CNV Pulse Width1  
SCK Period  
tCNVH  
tSCK  
10  
ns  
VIO > 2.7 V  
VIO > 1.7 V  
SCK Low Time  
SCK High Time  
9.8  
12.3  
3
ns  
ns  
ns  
ns  
tSCKL  
tSCKH  
3
READ OPERATION  
CNV Low to SDO D15 MSB Valid Delay  
VIO > 2.7 V  
VIO > 1.7 V  
SCK Falling Edge to Data Remains Valid  
SCK Falling Edge to Data Valid Delay  
VIO > 2.7 V  
tEN  
10  
13  
ns  
ns  
ns  
tHSDO  
tDSDO  
1.5  
7.5  
10.5  
20  
ns  
ns  
ns  
VIO > 1.7 V  
CNV Rising Edge to SDO High Impedance  
WRITE OPERATION  
tDIS  
SDI Valid Setup Time from SCK Rising Edge  
SDI Valid Hold Time from SCK Rising Edge  
CNV Rising Edge to SCK Edge Hold Time  
CNV Falling Edge to SCK Active Edge Setup Time  
tSSDISCK  
tHSDISCK  
tHCNVSCK  
tSCNVSCK  
2
2
0
6
ns  
ns  
ns  
ns  
1 For turbo mode, tCNVH must match the tQUIET1 minimum.  
Table 4. Achievable Throughput for Different Modes of Operation  
Parameter  
Test Conditions/Comments  
Min  
Typ  
Max  
Unit  
THROUGHPUT, CS MODE  
3-Wire and 4-Wire Turbo Mode  
fSCK = 100 MHz, VIO ≥ 2.7 V  
fSCK = 80 MHz, VIO < 2.7 V  
fSCK = 100 MHz, VIO ≥ 2.7 V  
fSCK = 80 MHz, VIO < 2.7 V  
fSCK = 100 MHz, VIO ≥ 2.7 V  
fSCK = 80 MHz, VIO < 2.7 V  
fSCK = 100 MHz, VIO ≥ 2.7 V  
fSCK = 80 MHz, VIO < 2.7 V  
2
2
2
1.86  
1.82  
1.69  
1.64  
1.5  
MSPS  
MSPS  
MSPS  
MSPS  
MSPS  
MSPS  
MSPS  
MSPS  
3-Wire and 4-Wire Turbo Mode and Six Status Bits  
3-Wire and 4-Wire Mode  
3-Wire and 4-Wire Mode and Six Status Bits  
Rev. B | Page 8 of 37  
 
Data Sheet  
AD4001/AD4005  
ABSOLUTE MAXIMUM RATINGS  
Note that the input overvoltage clamp cannot sustain the  
overvoltage condition for an indefinite amount of time.  
THERMAL RESISTANCE  
Thermal performance is directly linked to printed circuit board  
(PCB) design and operating environment. Careful attention to  
PCB thermal design is required.  
Table 5.  
Parameter  
Rating  
Analog Inputs  
IN+, IN− to GND1  
Table 6. Thermal Resistance  
−0.3 V to VREF + 0.4 V  
or 50 mA  
Package Type1  
RM-10  
θJA  
θJC  
38  
33  
Unit  
°C/W  
°C/W  
2
3
147  
114  
Supply Voltage  
REF, VIO to GND  
VDD to GND  
VDD to VIO  
Digital Inputs to GND  
Digital Outputs to GND  
Storage Temperature Range  
Junction Temperature  
Lead Temperature Soldering  
CP-10-9  
−0.3 V to +6.0 V  
−0.3 V to +2.1 V  
−6 V to +2.4 V  
−0.3 V to VIO + 0.3 V  
−0.3 V to VIO + 0.3 V  
−65°C to +150°C  
150°C  
1 Test Condition 1: thermal impedance simulated values are based upon use  
of 2S2P JEDEC PCB. See the Ordering Guide.  
2 θJA is the natural convection junction-to-ambient thermal resistance  
measured in a one cubic foot sealed enclosure.  
3 θJC is the junction-to-case thermal resistance.  
ESD CAUTION  
260°C reflow as per  
JEDEC J-STD-020  
ESD Ratings  
Human Body Model  
Machine Model  
Field Induced Charged Device Model  
4 kV  
200 V  
1.25 kV  
1 See the Analog Inputs section for an explanation of IN+ and IN−.  
Stresses at or above those listed under Absolute Maximum  
Ratings may cause permanent damage to the product. This is a  
stress rating only; functional operation of the product at these  
or any other conditions above those indicated in the operational  
section of this specification is not implied. Operation beyond  
the maximum operating conditions for extended periods may  
affect product reliability.  
Rev. B | Page 9 of 37  
 
 
 
AD4001/AD4005  
Data Sheet  
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS  
REF 1  
VDD 2  
IN+ 3  
10 VIO  
AD4001/  
AD4005  
9
8
7
6
SDI  
SCK  
SDO  
CNV  
TOP VIEW  
(Not to Scale)  
IN– 4  
1
2
3
4
5
10  
9
REF  
VDD  
IN+  
VIO  
GND 5  
SDI  
AD4001/  
AD4005  
8
SCK  
SDO  
CNV  
TOP VIEW  
NOTES  
IN–  
7
(Not to Scale)  
1. CONNECT THE EXPOSED PAD TO GND.  
THIS CONNECTION IS NOT REQUIRED TO  
MEET THE SPECIFIED PERFORMANCE.  
GND  
6
Figure 3. 10-Lead MSOP Pin Configuration  
Figure 4. 10-Lead LFCSP Pin Configuration  
Table 7. Pin Function Descriptions  
Pin No. Mnemonic Type1  
Description  
1
REF  
AI  
Reference Input Voltage. The VREF range is 2.4 V to 5.1 V. This pin is referred to the GND pin and must be  
decoupled closely to the GND pin with a 10 µF, X7R ceramic capacitor.  
2
VDD  
P
1.8 V Power Supply. The VDD range is 1.71 V to 1.89 V. Bypass VDD to GND with a 0.1 µF ceramic  
capacitor.  
3
4
5
6
IN+  
IN−  
GND  
CNV  
AI  
AI  
P
Differential Positive Analog Input. See the Differential Input Considerations section.  
Differential Negative Analog Input. See the Differential Input Considerations section.  
Power Supply Ground.  
Convert Input. This input has multiple functions. On its leading edge, it initiates the conversions and  
selects the interface mode of the device: daisy-chain mode or CS mode. In CS mode, the SDO pin is  
enabled when CNV is low. In daisy-chain mode, the data is read when CNV is high.  
DI  
7
8
9
SDO  
SCK  
SDI  
DO  
DI  
DI  
Serial Data Output. The conversion result is output on this pin. It is synchronized to SCK.  
Serial Data Clock Input. When the device is selected, the conversion result is shifted out by this clock.  
Serial Data Input. This input provides multiple features. It selects the interface mode of the ADC as  
follows:  
Daisy-chain mode is selected if SDI is low during the CNV rising edge. In this mode, SDI is used as a data  
input to daisy-chain the conversion results of two or more ADCs onto a single SDO line. The digital data  
level on SDI is output on SDO with a delay of 16 SCK cycles.  
CS mode is selected if SDI is high during the CNV rising edge. In this mode, either SDI or CNV can enable  
the serial output signals when low. If SDI or CNV is low when the conversion is complete, the busy  
indicator feature is enabled. With CNV low, the device can be programmed by clocking in a 16-bit word  
on SDI on the rising edge of SCK.  
10  
VIO  
P
P
Input/Output Interface Digital Power. Nominally, this pin is at the same supply as the host interface  
(1.8 V, 2.5 V, 3 V, or 5 V). Bypass VIO to GND with a 0.1 μF ceramic capacitor.  
Exposed Pad (LFCSP Only). Connect the exposed pad to GND. This connection is not required to meet  
the specified performance.  
N/A2  
EPAD  
1 AI is analog input, P is power, DI is digital input, and DO is digital output.  
2 N/A means not applicable.  
Rev. B | Page 10 of 37  
 
Data Sheet  
AD4001/AD4005  
TYPICAL PERFORMANCE CHARACTERISTICS  
VDD = 1.8 V, VIO = 3.3 V, VREF = 5 V, T = 25°C, high-Z mode disabled, span compression disabled, turbo mode enabled, and sampling  
frequency (fS) = 2 MSPS for the AD4001 and fS = 1 MSPS for the AD4005, unless otherwise noted.  
0.4  
0.4  
–40°C  
+25°C  
+125°C  
–40°C  
+25°C  
+125°C  
0.3  
0.3  
0.2  
0.2  
0.1  
0.1  
0
0
–0.1  
–0.2  
–0.3  
–0.4  
–0.1  
–0.2  
–0.3  
–0.4  
0
8192 16384 24576 32768 40960 49152 57344 65536  
CODE  
0
8192 16384 24576 32768 40960 49152 57344 65536  
CODE  
Figure 5. INL vs. Code for Various Temperatures, VREF = 5 V  
Figure 8. DNL vs. Code for Various Temperatures, VREF = 5 V  
0.4  
0.3  
0.4  
0.3  
–40°C  
+25°C  
+125°C  
–40°C  
+25°C  
+125°C  
0.2  
0.2  
0.1  
0.1  
0
0
–0.1  
–0.2  
–0.3  
–0.4  
–0.1  
–0.2  
–0.3  
–0.4  
0
8192 16384 24576 32768 40960 49152 57344 65536  
CODE  
0
8192 16384 24576 32768 40960 49152 57344 65536  
CODE  
Figure 6. INL vs. Code for Various Temperatures, VREF = 2.5 V  
Figure 9. DNL vs. Code for Various Temperatures, VREF = 2.5 V  
0.4  
0.3  
0.4  
HIGH-Z ENABLED  
SPAN COMPRESSION ENABLED  
HIGH-Z ENABLED  
SPAN COMPRESSION ENABLED  
0.3  
0.2  
0.2  
0.1  
0.1  
0
0
–0.1  
–0.2  
–0.3  
–0.4  
–0.1  
–0.2  
–0.3  
–0.4  
0
8192 16384 24576 32768 40960 49152 57344 65536  
CODE  
0
8192 16384 24576 32768 40960 49152 57344 65536  
CODE  
Figure 10. DNL vs. Code, High-Z and Span Compression Modes Enabled,  
REF = 5 V  
Figure 7. INL vs. Code, High-Z and Span Compression Modes Enabled, VREF = 5 V  
V
Rev. B | Page 11 of 37  
 
AD4001/AD4005  
Data Sheet  
1200000  
600000  
500000  
400000  
300000  
200000  
100000  
0
V
V
= 5V  
V
V
= 5V  
REF  
REF  
REF  
REF  
= 2.5V  
= 2.5V  
1000000  
800000  
600000  
400000  
200000  
0
32766  
32767  
32768  
CODE  
32769  
32770  
32766  
32767  
32768  
CODE  
32769  
32770  
Figure 11. Histogram of a DC Input at Code Center, VREF = 2.5 V  
and VREF = 5 V  
Figure 14. Histogram of a DC Input at Code Transition, VREF = 2.5 V  
and VREF = 5 V  
0
0
V
= 5V  
V
= 2.5V  
REF  
REF  
SNR = 96.25dB  
THD = –124.30dB  
SINAD = 96.23dB  
SNR = 93.12dB  
THD = –118.26dB  
SINAD = 93.11dB  
–20  
–40  
–20  
–40  
–60  
–60  
–80  
–80  
–100  
–120  
–140  
–160  
–180  
–100  
–120  
–140  
–160  
–180  
100  
1k  
10k  
100k  
1M  
100  
1k  
10k  
100k  
1M  
FREQUENCY (Hz)  
FREQUENCY (Hz)  
Figure 12. 1 kHz, −0.5 dBFS Input Tone FFT, Wide View, VREF = 5 V  
Figure 15. 1 kHz, −0.5 dBFS Input Tone FFT, Wide View, VREF = 2.5 V  
0
0
V
= 5V  
V
= 5V  
REF  
REF  
SNR = 91.04dB  
THD = –91.47dB  
SINAD = 88.85dB  
SNR = 95.48dB  
THD = –98.63dB  
SINAD = 93.84dB  
–20  
–40  
–20  
–40  
–60  
–60  
–80  
–80  
–100  
–120  
–140  
–160  
–180  
–100  
–120  
–140  
–160  
–180  
1k  
10k  
100k  
1M  
1k  
10k  
100k  
1M  
FREQUENCY (Hz)  
FREQUENCY (Hz)  
Figure 13. 100 kHz, −0.5 dBFS Input Tone FFT, Wide View  
Figure 16. 400 kHz, −0.5 dBFS Input Tone FFT, Wide View  
Rev. B | Page 12 of 37  
Data Sheet  
AD4001/AD4005  
15.8  
15.7  
15.6  
15.5  
15.4  
15.3  
15.2  
15.1  
–116  
–118  
–120  
–122  
–124  
–126  
–128  
–130  
–132  
129  
128  
127  
126  
125  
124  
123  
122  
121  
120  
96.5  
ENOB  
SFDR  
THD  
SNR  
SINAD  
96.0  
95.5  
95.0  
94.5  
94.0  
93.5  
93.0  
92.5  
2.4  
2.7  
3.0  
3.3  
3.6  
3.9  
4.2  
4.5  
4.8  
5.1  
2.4  
2.7  
3.0  
3.3  
3.6  
3.9  
4.2  
4.5  
4.8  
5.1  
REFERENCE VOLTAGE (V)  
REFERENCE VOLTAGE (V)  
Figure 17. SNR, SINAD, and ENOB vs. Reference Voltage, fIN = 1 kHz  
Figure 20. THD and SFDR vs. Reference Voltage, fIN = 1 kHz  
96.5  
15.73  
15.72  
15.71  
15.70  
15.69  
15.68  
15.67  
15.66  
15.65  
15.64  
15.63  
–118  
127.1  
THD  
SFDR  
–119  
–120  
–121  
–122  
–123  
–124  
–125  
–126  
–127  
–128  
–129  
127.0  
126.9  
126.8  
126.7  
126.6  
126.5  
126.4  
126.3  
96.4  
96.3  
96.2  
96.1  
96.0  
95.9  
SNR  
SINAD  
ENOB  
–40  
–20  
0
20  
40  
60  
80  
100  
120  
–40  
–20  
0
20  
40  
60  
80  
100  
120  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
Figure 18. SNR, SINAD, and ENOB vs. Temperature, fIN = 1 kHz  
Figure 21. THD and SFDR vs. Temperature, fIN = 1 kHz  
130  
97  
96  
95  
94  
93  
92  
91  
90  
89  
DYNAMIC RANGE  
FREQUENCY = 1kHz  
FREQUENCY = 10kHz  
125  
120  
115  
110  
105  
100  
95  
VIO = 1.89V  
VIO = 3.6V  
VIO = 5.5V  
1
2
4
8
16  
32  
64  
128 256 512 1024  
0
20  
40  
60  
80  
100  
DECIMATION RATE  
tQUIET2 (ns)  
Figure 19. SNR vs. Decimation Rate for Various Input Frequencies, 2 MSPS  
Figure 22. SINAD vs. tQUIET2  
Rev. B | Page 13 of 37  
 
AD4001/AD4005  
Data Sheet  
1.0  
0.8  
60  
59  
58  
57  
56  
55  
54  
ZERO ERROR  
PFS ERROR  
NFS ERROR  
0.6  
0.4  
0.2  
0
–0.2  
–0.4  
–0.6  
–0.8  
–1.0  
–40  
–20  
0
20  
40  
60  
80  
100  
120  
0
1
2
3
4
5
6
7
8
9
10  
TEMPERATURE (°C)  
TIME (Seconds)  
Figure 23. 1/f Noise for 0.1 Hz to 10 Hz Bandwidth, 50 kSPS, 2500 Samples  
Averaged per Reading  
Figure 25. Zero Error and Gain Error vs. Temperature, Positive Full Scale (PFS)  
and Negative Full Scale (NFS)  
8
7
6
4.5  
4.0  
3.5  
3.0  
5
2.5  
VDD HIGH-Z DISABLED  
VDD HIGH-Z ENABLED  
REF HIGH-Z DISABLED  
REF HIGH-Z ENABLED  
VIO HIGH-Z DISABLED  
VIO HIGH-Z ENABLED  
4
3
2
1
0
VDD HIGH-Z ENABLED  
2.0  
1.5  
1.0  
0.5  
0
VDD HIGH-Z DISABLED  
REF HIGH-Z ENABLED  
REF HIGH-Z DISABLED  
VIO HIGH-Z ENABLED  
VIO HIGH-Z DISABLED  
–40  
–20  
0
20  
40  
60  
80  
100  
120  
–40  
–20  
0
20  
40  
60  
80  
100  
120  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
Figure 24. Operating Current vs. Temperature, AD4001, 2 MSPS  
Figure 26. Operating Current vs. Temperature, AD4005, 1 MSPS  
Rev. B | Page 14 of 37  
 
Data Sheet  
AD4001/AD4005  
1.1  
25.0  
22.5  
20.0  
17.5  
15.0  
12.5  
10.0  
7.5  
2MSPS  
1MSPS  
1.0  
0.9  
0.8  
0.7  
0.6  
0.5  
0.4  
0.3  
0.2  
5.0  
2.5  
0
–40  
2.4  
2.7  
3.0  
3.3  
3.6  
3.9  
4.2  
4.5  
4.8  
5.1  
–20  
0
20  
40  
60  
80  
100  
120  
REFERENCE VOLTAGE (V)  
TEMPERATURE (°C)  
Figure 29. Standby Current vs. Temperature  
Figure 27. Reference Current vs. Reference Voltage  
23  
21  
19  
17  
15  
13  
11  
9
VIO = 5V  
VIO = 3.3V  
VIO = 1.8V  
7
5
0
20  
40  
60  
80 100 120 140 160 180 200 220  
LOAD CAPACITANCE (pF)  
Figure 28. tDSDO vs. Load Capacitance  
Rev. B | Page 15 of 37  
AD4001/AD4005  
Data Sheet  
TERMINOLOGY  
Integral Nonlinearity Error (INL)  
Dynamic Range  
INL is the deviation of each individual code from a line drawn  
from negative full scale through positive full scale. The point  
used as negative full scale occurs ½ LSB before the first code  
transition. Positive full scale is defined as a level 1½ LSB beyond  
the last code transition. The deviation is measured from the  
middle of each code to the true straight line (see Figure 31).  
Dynamic range is the ratio of the rms value of the full scale to  
the total rms noise measured. The value for dynamic range is  
expressed in decibels. It is measured with a signal at −60 dBFS  
so that it includes all noise sources and DNL artifacts.  
Signal-to-Noise Ratio (SNR)  
SNR is the ratio of the rms value of the actual input signal to the  
rms sum of all other spectral components below the Nyquist  
frequency, excluding harmonics and dc. The value for SNR is  
expressed in decibels.  
Differential Nonlinearity Error (DNL)  
In an ideal ADC, code transitions are 1 LSB apart. DNL is the  
maximum deviation from this ideal value. It is often specified in  
terms of resolution for which no missing codes are guaranteed.  
Signal-to-Noise-and-Distortion Ratio (SINAD)  
Zero Error  
SINAD is the ratio of the rms value of the actual input signal to  
the rms sum of all other spectral components that are less than  
the Nyquist frequency, including harmonics but excluding dc.  
The value of SINAD is expressed in decibels.  
Zero error is the difference between the ideal midscale voltage,  
that is, 0 V, from the actual voltage producing the midscale  
output code, that is, 0 LSB.  
Gain Error  
Aperture Delay  
The first transition (from 100 ... 00 to 100 ... 01) occurs at a level  
½ LSB above nominal negative full scale (−4.999981 V for the  
5 V range). The last transition (from 011 … 10 to 011 … 11)  
occurs for an analog voltage 1½ LSB below the nominal full  
scale (+4.999943 V for the 5 V range). The gain error is the  
deviation of the difference between the actual level of the last  
transition and the actual level of the first transition from the  
difference between the ideal levels.  
Aperture delay is the measure of the acquisition performance  
and is the time between the rising edge of the CNV input and  
when the input signal is held for a conversion.  
Transient Response  
Transient response is the time required for the ADC to acquire a  
full-scale input step to 1 LSB accuracy.  
Common-Mode Rejection Ratio (CMRR)  
CMRR is the ratio of the power in the ADC output at the  
frequency, f, to the power of a 200 mV p-p sine wave applied to  
the common-mode voltage of IN+ and IN− of frequency, f.  
Spurious-Free Dynamic Range (SFDR)  
SFDR is the difference, in decibels (dB), between the rms  
amplitude of the input signal and the peak spurious signal.  
CMRR (dB) = 10log(PADC_IN/PADC_OUT  
where:  
ADC_IN is the common-mode power at the frequency, f, applied  
to the IN+ and IN− inputs.  
ADC_OUT is the power at the frequency, f, in the ADC output.  
)
Effective Number of Bits (ENOB)  
ENOB is a measurement of the resolution with a sine wave  
input. It is related to SINAD as follows:  
P
ENOB = (SINADdB − 1.76)/6.02  
P
ENOB is expressed in bits.  
Power Supply Rejection Ratio (PSRR)  
Total Harmonic Distortion (THD)  
PSRR is the ratio of the power in the ADC output at the  
frequency, f, to the power of a 200 mV p-p sine wave applied to  
the ADC VDD supply of frequency, f.  
THD is the ratio of the rms sum of the first five harmonic  
components to the rms value of a full-scale input signal and is  
expressed in decibels.  
PSRR (dB) = 10 log(PVDD_IN/PADC_OUT  
)
where:  
P
P
VDD_IN is the power at the frequency, f, at the VDD pin.  
ADC_OUT is the power at the frequency, f, in the ADC output.  
Rev. B | Page 16 of 37  
 
Data Sheet  
AD4001/AD4005  
THEORY OF OPERATION  
IN+  
SWITCHES CONTROL  
CONTROL  
SW+  
SW–  
MSB  
LSB  
LSB  
32,768C 16,384C  
4C  
4C  
2C  
2C  
C
C
C
C
BUSY  
REF  
COMP  
LOGIC  
GND  
32,768C 16,384C  
MSB  
OUTPUT CODE  
CNV  
IN–  
Figure 30. ADC Simplified Schematic  
For single-supply applications, a span compression feature  
creates additional headroom and footroom for the driving  
amplifier to access the full range of the ADC.  
CIRCUIT INFORMATION  
The AD4001/AD4005 are high speed, low power, single-supply,  
precise, 16-bit ADCs based on a SAR architecture.  
The fast conversion time of the AD4001/AD4005, along with turbo  
mode, allows low clock rates to read back conversions even when  
running at their maximum throughput rates of 2 MSPS/1 MSPS.  
Note that, for the AD4001, a throughput rate of 2 MSPS can be  
achieved only with turbo mode enabled.  
The AD4001 is capable of converting 2,000,000 samples per  
second (2 MSPS), the AD4005 is capable of converting 1,000,000  
samples per second (1 MSPS). The power consumption of the  
AD4001/AD4005 scales with throughput because they power  
down in between conversions. When operating at 10 kSPS, for  
example, they typically consume 80 µW, making them ideal for  
battery-powered applications. The AD4001/AD4005 also have a  
valid first conversion after being powered down for long periods,  
which can further reduce power consumed in applications in  
which the ADC does not need to be constantly converting.  
The AD4001/AD4005 can interface with any 1.8 V to 5 V digital  
logic family. They are available in a 10-lead MSOP or a tiny  
10-lead LFCSP that allows space savings and flexible  
configurations.  
The AD4001/AD4005 are pin for pin compatible with some of  
the 14-/16-/18-/20-bit precision SAR ADCs listed in Table 8.  
The AD4001/AD4005 provide the user with an on-chip track-  
and-hold and do not exhibit any pipeline delay or latency,  
making them ideal for multiplexed applications.  
Table 8. MSOP and LFCSP 14-/16-/18-/20-Bit Precision SAR  
ADCs  
The AD4001/AD4005 incorporate a multitude of unique ease of  
use features that result in a lower system power and footprint.  
400 kSPS to  
250 kSPS 500 kSPS  
Bits 100 kSPS  
201  
≥1000 kSPS  
AD40202  
The AD4001/AD4005 each have an internal voltage clamp that  
protects the device from overvoltage damage on the analog inputs.  
181  
AD7989-12  
AD76912  
AD76902,  
AD7989-52,  
AD40112  
AD40032,  
AD40072,  
AD79822,  
AD79842  
The analog input incorporates circuitry that reduces the nonlinear  
charge kickback seen from a typical switched capacitor SAR input.  
This reduction in kickback, combined with a longer acquisition  
phase, means reduced settling requirements on the driving  
amplifier. This combination allows the use of lower bandwidth  
and lower power amplifiers as drivers. It has the additional benefit  
of allowing a larger resistor value in the input RC filter and a  
corresponding smaller capacitor, which results in a smaller RC  
load for the amplifier, improving stability and power dissipation.  
161  
163  
AD7684  
AD76872  
AD76882,  
AD76932,  
AD79162  
AD4001,  
AD4005,  
AD79152  
AD40002,  
AD40042,  
AD7980,2  
AD79832  
AD7680,  
AD7683,  
AD7988-12  
AD76852,  
AD7694  
AD76862,  
AD7988-52  
143  
AD7940  
AD79422  
AD79462  
Not applicable  
High-Z mode can be enabled via the SPI interface by programming  
a register bit (see Table 14). When high-Z mode is enabled, the  
ADC input has a low input charging current at low input signal  
frequencies, as well as improved distortion over a wide frequency  
range up to 100 kHz. For frequencies greater than 100 kHz and  
multiplexing, disable high-Z mode.  
1 True differential.  
2 Pin for pin compatible.  
3 Pseudo differential.  
Rev. B | Page 17 of 37  
 
 
 
 
AD4001/AD4005  
Data Sheet  
the completion of this process, the control logic generates the  
ADC output code and a busy signal indicator.  
CONVERTER OPERATION  
The AD4001/AD4005 are SAR-based ADCs using a charge  
redistribution sampling digital-to-analog converter (DAC).  
Figure 30 shows the simplified schematic of the ADC. The  
capacitive DAC consists of two identical arrays of 16 binary  
weighted capacitors, which are connected to the comparator inputs.  
Because the AD4001 and the AD4005 have on-board conversion  
clocks, the serial clock, SCK, is not required for the conversion  
process.  
TRANSFER FUNCTIONS  
During the acquisition phase, terminals of the array tied to the  
input of the comparator are connected to GND via the SW+ and  
SW− switches. All independent switches connect the other  
terminal of each capacitor to the analog inputs. Therefore, the  
capacitor arrays are used as sampling capacitors and acquire the  
analog signal on the IN+ and IN− inputs.  
The ideal transfer characteristics for the AD4001/AD4005 are  
shown in Figure 31 and Table 9.  
011...111  
011...110  
011...101  
When the acquisition phase is complete and the CNV input  
goes high, a conversion phase initiates. When the conversion  
phase begins, SW+ and SW− are opened first. The two capacitor  
arrays are then disconnected from the inputs and connected to  
the GND input. The differential voltage between the IN+ and  
IN− inputs captured at the end of the acquisition phase is  
applied to the comparator inputs, causing the comparator to  
become unbalanced. By switching each element of the capacitor  
array between GND and VREF, the comparator input varies by  
binary weighted voltage steps (VREF/2, VREF/4, …, VREF/65,536).  
The control logic toggles these switches, starting with the MSB,  
to bring the comparator back into a balanced condition. After  
100...010  
100...001  
100...000  
–FSR  
–FSR + 1 LSB  
+FSR – 1 LSB  
+FSR – 1.5 LSB  
ANALOG INPUT  
–FSR + 0.5 LSB  
Figure 31. ADC Ideal Transfer Function (FSR Is Full-Scale Range)  
Table 9. Output Codes and Ideal Input Voltages  
Description  
+FSR − 1 LSB  
Midscale + 1 LSB  
Midscale  
Midscale − 1 LSB  
−FSR + 1 LSB  
−FSR  
Analog Input, VREF = 5 V  
+4.999847 V  
+152.6 µV  
0 V  
−152.6 µV  
−4.999847 V  
−5 V  
VREF = 5 V with Span Compression Enabled  
Digital Output Code (Hex)  
+3.999878 V  
+122.1 µV  
0 V  
−122.1 µV  
−3.999878 V  
−4 V  
0x7FFF1  
0x0001  
0x0000  
0xFFFF  
0x8001  
0x80002  
1 This output code is also the code for an overranged analog input (VIN+ − VIN− above VREF with span compression disabled and above 0.8 × VREF with span compression  
enabled).  
2 This output code is also the code for an underranged analog input (VIN+ − VIN− below −VREF with span compression disabled and below −0.8 × VREF with span  
compression enabled).  
Rev. B | Page 18 of 37  
 
 
 
 
Data Sheet  
AD4001/AD4005  
APPLICATIONS INFORMATION  
Figure 33 shows a recommended connection diagram when  
using a single-supply system. This setup is preferable when only  
a limited number of rails are available in the system and power  
dissipation is of critical importance.  
TYPICAL APPLICATION DIAGRAMS  
Figure 32 shows an example of the recommended connection  
diagram for the AD4001/AD4005 when multiple supplies are  
available. This configuration is used for best performance  
because the amplifier supplies can be selected to allow the  
maximum signal range.  
Figure 34 shows a recommended connection diagram when  
using a fully differential amplifier.  
V+ +6.5V  
REF  
LDO  
1.8V  
AMP  
V
= V  
/2  
CM  
REF  
5V  
0.1µF  
10kΩ  
10µF  
0.1µF 1.8V TO 5V  
HOST  
SUPPLY  
10kΩ  
V+  
R
AMP  
V
REF  
V
= V  
/2  
REF  
VDD  
VIO  
SDI  
CM  
REF  
C
0V  
IN+  
IN–  
V–  
V+  
SCK  
DIGITAL HOST  
(MICROPROCESSOR/  
FPGA)  
AD4001/AD4005  
SDO  
CNV  
R
GND  
AMP  
V
REF  
V
= V  
/2  
3-WIRE/4-WIRE  
INTERFACE  
CM  
REF  
C
0V  
V–  
V– –0.5V  
Figure 32. Typical Application Diagram with Multiple Supplies  
V+ = +5V  
1
REF  
LDO  
AMP  
V
= V  
/2  
CM  
REF  
4.096V  
1
1.8V  
0.1µF 1.8V TO 5V  
10kΩ  
0.1µF  
HOST  
SUPPLY  
10µF  
10kΩ  
100nF  
100nF  
R
AMP  
0.9 × V  
/2  
REF  
V
= V  
REF  
CM  
REF  
VDD VIO  
C
0.1 × V  
REF  
SDI  
IN+  
IN–  
SCK  
DIGITAL HOST  
(MICROPROCESSOR/  
FPGA)  
AD4001/AD40052  
SDO  
CNV  
R
GND  
AMP  
0.9 × V  
/2  
REF  
3-WIRE/4-WIRE  
INTERFACE  
V
= V  
REF  
CM  
C
0.1 × V  
REF  
3
1
SEE THE VOLTAGE REFERENCE INPUT SECTION FOR REFERENCE SELECTION. C  
SPAN COMPRESSION MODE ENABLED.  
SEE TABLE 10 FOR RC FILTER AND AMPLIFIER SELECTION.  
IS USUALLY A 10µF CERAMIC CAPACITOR (X7R).  
REF  
2
3
Figure 33. Typical Application Diagram with a Single Supply  
Rev. B | Page 19 of 37  
 
 
 
 
AD4001/AD4005  
Data Sheet  
V+ = +5V  
REF  
LDO  
AMP  
4.096V  
V
= V  
/2  
CM  
REF  
1.8V  
R4  
1kΩ  
R3  
1kΩ  
V
1.8V TO 5V  
0.1µF  
0.1µF  
HOST  
SUPPLY  
REF  
10kΩ  
10µF  
V
= V  
/2  
CM  
REF  
10kΩ  
0
V+  
+IN  
–IN  
REF  
VDD  
VIO  
R
–OUT  
SDI  
IN+  
C
C
SCK  
DIGITAL HOST  
(MICROPROCESSOR/  
FPGA)  
V
= V  
/2  
CM  
REF  
AD4001/AD4005  
V
OCM  
SDO  
CNV  
+OUT  
0.1µF  
IN–  
R
DIFFERENTIAL  
AMPLIFIER  
GND  
3-WIRE/4-WIRE  
INTERFACE  
V–  
R1  
1kΩ  
V
REF  
V
= V  
/2  
CM  
REF  
0
R2  
1kΩ  
Figure 34. Typical Application Diagram with a Fully Differential Amplifier  
V+ = +5V  
REF  
LDO  
AMP  
V
= V /2  
REF  
CM  
4.096V  
1.8V  
R4  
1kΩ  
R3  
1kΩ  
1.8V TO 5V  
+V  
0.1µF 0.1µF  
REF  
HOST  
SUPPLY  
10kΩ  
10µF  
0V  
–V  
10kΩ  
REF  
V+  
+IN  
REF  
VDD  
VIO  
R
R
–OUT  
SDI  
IN+  
C
C
V
/2  
SCK  
REF  
DIGITAL HOST  
(MICROPROCESSOR/  
FPGA)  
V
AD4001/AD4005  
OCM  
SDO  
CNV  
+OUT  
0.1µF  
IN–  
DIFFERENTIAL  
AMPLIFIER  
GND  
–IN  
3-WIRE/4-WIRE  
INTERFACE  
V–  
R1  
1kΩ  
R2  
1kΩ  
Figure 35. Typical Application Diagram for Single-Ended to Differential Conversion with a Fully Differential Amplifier  
Input Overvoltage Clamp Circuit  
ANALOG INPUTS  
Most ADC analog inputs, IN+ and IN−, have no overvoltage  
protection circuitry apart from ESD protection diodes. During  
an overvoltage event, an ESD protection diode from an analog  
input (IN+ or IN−) pin to REF forward biases and shorts the  
input pin to REF, potentially overloading the reference or causing  
damage to the device. The AD4001/AD4005 internal overvoltage  
clamp circuit with a larger external resistor (REXT = 200 Ω)  
eliminates the need for external protection diodes and protects  
the ADC inputs against dc overvoltages.  
Figure 36 shows an equivalent circuit of the analog input  
structure, including the overvoltage clamp of the  
AD4001/AD4005.  
REF  
D1  
C
IN  
R
R
IN  
IN+/IN–  
EXT  
0V TO 15V  
C
C
D2  
V
CLAMP  
EXT  
PIN  
IN  
In applications where the amplifier rails are greater than VREF  
and less than ground, it is possible for the output to exceed the  
input voltage range of the device. In this case, the AD4001/AD4005  
internal voltage clamp circuit ensures that the voltage on the  
input pin does not exceed VREF + 0.4 V and prevents damage to  
GND  
Figure 36. Equivalent Analog Input Circuit  
Rev. B | Page 20 of 37  
 
 
 
 
Data Sheet  
AD4001/AD4005  
72  
71  
70  
69  
68  
67  
66  
the device by clamping the input voltage in a safe operating  
range and avoiding disturbance of the reference, which is  
particularly important for systems that share the reference  
among multiple ADCs.  
If the analog input exceeds the reference voltage by 0.4 V, t h e  
internal clamp circuit turns on and the current flows through  
the clamp into ground, preventing the input from rising further  
and potentially causing damage to the device. The clamp turns  
on before D1 (see Figure 36) and can sink up to 50 mA of current.  
OV  
When the clamp is active, it sets the  
clamp flag bit in the  
register that can be read back (see Table 14), which is a sticky bit  
that must be read to be cleared. The status of the clamp can also  
be checked in the status bits using an overvoltage clamp flag  
(see Table 15). The clamp circuit does not dissipate static power  
in the off state. Note that the clamp cannot sustain the overvoltage  
condition for an indefinite amount of time.  
100  
1k  
10k  
100k  
1M  
FREQUENCY (Hz)  
Figure 37. CMRR vs. Frequency, VDD = 1.8 V, VIO = 3.3 V, VREF = 5 V, 25°C  
Switched Capacitor Input  
During the acquisition phase, the impedance of the analog  
inputs (IN+ or IN−) can be modeled as a parallel combination  
of Capacitor CPIN and the network formed by the series connection  
of RIN and CIN. CPIN is primarily the pin capacitance. RIN is typically  
400 Ω and is a lumped component composed of serial resistors  
and the on resistance of the switches. CIN is typically 40 pF and  
is mainly the ADC sampling capacitor.  
The external RC filter is usually present at the ADC input to  
band limit the input signal. During an overvoltage event, excessive  
voltage is dropped across REXT, and REXT becomes part of a  
protection circuit. The REXT value can vary from 200 Ω to 20 kΩ  
for 15 V protection. The CEXT value can be as low as 100 pF for  
correct operation of the clamp. See Table 1 for input overvoltage  
clamp specifications.  
During the conversion phase, where the switches are open, the  
input impedance is limited to CPIN. RIN and CIN make a single-  
pole, low-pass filter that reduces undesirable aliasing effects and  
limits noise.  
Differential Input Considerations  
The analog input structure allows the sampling of the true  
differential signal between IN+ and IN−. By using these differential  
inputs, signals common to both inputs are rejected. Figure 37  
shows the common-mode rejection capability of the AD4001/  
AD4005 over frequency. It is important to note that the differential  
input signals must be truly antiphase in nature, 180° out of phase,  
which is required to keep the common-mode voltage of the input  
signal within the specified range around VREF/2 as shown in Table 1.  
RC Filter Values  
The RC filter value (represented by R and C in Figure 32 to  
Figure 35) and driving amplifier can be selected depending on  
the input signal bandwidth of interest at the full throughput.  
Lower input signal bandwidth means that the RC cutoff can be  
lower, thereby reducing noise into the converter. For optimum  
performance at various throughputs, use the recommended RC  
values (200 Ω, 180 pF) and the ADA4807-1.  
The RC values shown in Table 10 are chosen for ease of  
drive considerations and greater ADC input protection. The  
combination of a large R value (200 Ω) and small C value  
results in a reduced dynamic load for the amplifier to drive. The  
smaller value of C means fewer stability and phase margin  
concerns with the amplifier. The large value of R limits the current  
into the ADC input when the amplifier output exceeds the ADC  
input range.  
Table 10. RC Filter and Amplifier Selection for Various Input Bandwidths  
Input Signal Bandwidth (kHz)  
R (Ω) C (pF)  
Recommended Amplifier  
See the High-Z Mode section  
ADA4807-1  
ADA4897-1  
ADA4897-1  
Recommended Fully Differential Amplifier  
<10  
<200  
>200  
Multiplexed  
ADA4940-1  
ADA4940-1  
ADA4932-1  
ADA4932-1  
200  
200  
200  
180  
120  
120  
Rev. B | Page 21 of 37  
 
 
 
AD4001/AD4005  
Data Sheet  
97  
96  
95  
94  
93  
92  
91  
90  
89  
88  
15.8  
15.6  
15.4  
15.2  
15.0  
14.8  
14.6  
14.4  
14.2  
DRIVER AMPLIFIER CHOICE  
Although the AD4001/AD4005 are easy to drive, the driver  
amplifier must meet the following requirements:  
The noise generated by the driver amplifier must be kept  
low enough to preserve the SNR and transition noise  
performance of the AD4001/AD4005. The noise from the  
driver is filtered by the single-pole, low-pass filter of the  
AD4001/AD4005 analog input circuit made by RIN and CIN,  
or by the external filter, if one is used. Because the typical  
noise of the AD4001/AD4005 is 54 µV rms, the SNR  
degradation due to the amplifier is  
SNR  
SINAD  
ENOB  
14.0  
1M  
1k  
10k  
100k  
INPUT FREQUENCY (Hz)  
54µV  
Figure 38. SNR, SINAD, and ENOB vs. Input Frequency, VDD = 1.8 V,  
VIO = 3.3 V, VREF = 5 V, 25°C  
SNRLOSS = 20 log  
π
54µV2 + f3dB (NeN )2  
–90  
125  
120  
115  
110  
105  
100  
95  
2
–95  
where:  
f
−3 dB is the input bandwidth, in megahertz, of the AD4001/  
AD4005 (10 MHz) or the cutoff frequency of the input  
filter, if one is used.  
THD  
SFDR  
–100  
–105  
–110  
–115  
–120  
–125  
N is the noise gain of the amplifier (for example, 1 in buffer  
configuration).  
eN is the equivalent input noise voltage of the op amp in  
nV/√Hz.  
For ac applications, the driver must have a THD  
performance commensurate with the AD4001/AD4005.  
For multichannel multiplexed applications, the driver  
amplifier and the analog input circuit of the AD4001/AD4005  
must settle for a full-scale step onto the capacitor array at a  
16-bit level (0.0001525%, 15.25 ppm). In the data sheet of  
the amplifier, settling at 0.1% to 0.01% is more commonly  
specified. This settling may differ significantly from the  
settling time at a 16-bit level and must be verified prior to  
driver selection.  
90  
1M  
1k  
10k  
100k  
INPUT FREQUENCY (Hz)  
Figure 39. THD and SFDR vs. Input Frequency, VDD = 1.8 V, VIO = 3.3 V,  
VREF = 5 V, 25°C  
Multiplexed Applications  
The AD4001/AD4005 significantly reduce system complexity  
and cost for multiplexed applications that require superior  
performance in terms of noise, power, and throughput. Figure 40  
shows a simplified block diagram of a multiplexed data  
acquisition system including a multiplexer, an ADC driver, and  
the precision SAR ADC.  
Single to Differential Driver  
For applications using a single-ended analog signal, either bipolar  
or unipolar, the ADA4940-1 single-ended to differential driver  
allows a differential input to the device. The schematic is shown  
in Figure 35.  
MULTIPLEXER  
R
ADC  
DRIVER  
SAR ADC  
C
High Frequency Input Signals  
R
The AD4001/AD4005 ac performance over a wide input frequency  
range (using a 5 V reference voltage) is shown in Figure 38 and  
Figure 39. Unlike other traditional SAR ADCs, the AD4001/  
AD4005 maintain exceptional ac performance for input  
frequencies up to the Nyquist frequency with minimal  
performance degradation. Note that the input frequency is  
limited to the Nyquist frequency of the sample rate in use.  
C
C
R
C
Figure 40. Multiplexed Data Acquisition Signal Chain Using the  
AD4001/AD4005  
Switching multiplexer channels typically results in large voltage  
steps at the ADC inputs. To ensure an accurate conversion result,  
the step must be given adequate time to settle before the ADC  
samples its inputs (on the rising edge of CNV). The settling  
time error is dependent on the drive circuitry (multiplexer and  
ADC driver), RC filter values, and the time when the multiplexer  
Rev. B | Page 22 of 37  
 
 
 
 
Data Sheet  
AD4001/AD4005  
15  
12  
9
channels are switched. Switch the multiplexer channels  
immediately after tQUIET1 has elapsed from the start of the  
conversion to maximize settling time while preventing  
corruption of the conversion result. To avoid conversion  
corruption, do not switch the channels during the tQUIET1 time. If  
the analog inputs are multiplexed during the quiet conversion  
time (tQUIET1), the current conversion may be corrupted.  
HIGH-Z DISABLED, 2MSPS  
HIGH-Z DISABLED, 1MSPS  
HIGH-Z ENABLED, 2MSPS  
HIGH-Z ENABLED, 1MSPS  
6
3
0
–3  
–6  
–9  
–12  
–15  
EASE OF DRIVE FEATURES  
Input Span Compression  
In single-supply applications, it is desirable to use the full range  
of the ADC; however, the amplifier can have some headroom  
and footroom requirements, which can be a problem, even if it  
is a rail-to-rail input and output amplifier. The AD4001/  
AD4005 include a span compression increases the headroom  
and footroom available to the amplifier by reducing the input  
range by 10% from the top and bottom of the range while still  
accessing all available ADC codes (see Figure 41). The SNR  
decreases by approximately 1.9 dB (20 × log(8/10)) for the reduced  
input range when span compression is enabled. Span compression  
is disabled by default but can be enabled by writing to the relevant  
register bit (see the Digital Interface section).  
–5  
–4  
–3  
–2  
–1  
0
1
2
3
4
5
INPUT DIFFERENTIAL VOLTAGE (V)  
Figure 42. Input Current vs. Input Differential Voltage, VDD = 1.8 V,  
VIO = 3.3 V, VREF = 5 V, 25°C  
To achieve the optimum data sheet performance from high  
resolution precision SAR ADCs, system designers are often  
forced to use a dedicated high power, high speed amplifier to  
drive the traditional switched capacitor SAR ADC inputs for  
their precision applications, which is commonly encountered in  
designing a precision data acquisition signal chain. The benefits  
of high-Z mode are low input current for slow (<10 kHz) or dc  
type signals and improved distortion (THD) performance over  
a frequency range of up to 100 kHz. High-Z mode allows a  
choice of lower power and lower bandwidth precision amplifiers  
with a lower RC filter cutoff to drive the ADC, removing the need  
for dedicated high speed ADC drivers, which saves system power,  
size, and cost in precision, low bandwidth applications. High-Z  
mode allows the amplifier and RC filter in front of the ADC to  
be chosen based on the signal bandwidth of interest and not  
based on the settling requirements of the switched capacitor SAR  
ADC inputs.  
90% OF V  
= 3.69V  
REF  
DIGITAL OUTPUT  
+FSR  
V
= 4.096V  
ADC  
5V  
REF  
10% OF V  
= 0.41V  
REF  
N
ALL 2  
CODES  
IN+/IN–  
ANALOG  
INPUT  
–FSR  
Figure 41. Span Compression  
High-Z Mode  
The AD4001/AD4005 incorporate high-Z mode, which reduces  
the nonlinear charge kickback when the capacitor DAC switches  
back to the input at the start of acquisition. Figure 42 shows the  
input current of the AD4001/AD4005 with high-Z mode enabled  
and disabled. The low input current makes the ADC easier to  
drive than the traditional SAR ADCs available in the market,  
even with high-Z mode disabled. The input current reduces  
further to submicroampere range when high-Z mode is enabled.  
The high-Z mode is disabled by default but can be enabled by  
writing to the register (see Table 14). Disable high-Z mode for  
input frequencies above 100 kHz or when multiplexing.  
Additionally, the AD4001/AD4005 can be driven with a much  
higher source impedance than traditional SARs, which means the  
resistor in the RC filter can have a value 10 times larger than  
previous SAR designs and, with high-Z mode enabled, can  
tolerate even larger impedance. Figure 43 shows the THD  
performance for various source impedances with high-Z mode  
disabled and enabled.  
Rev. B | Page 23 of 37  
 
 
 
 
AD4001/AD4005  
Data Sheet  
–80  
–80  
–85  
–85  
–90  
–90  
–95  
–95  
–100  
–105  
–100  
–105  
–110  
–115  
–120  
–125  
150Ω HIGH-Z DISABLED  
150Ω HIGH-Z ENABLED  
510Ω HIGH-Z DISABLED  
510Ω HIGH-Z ENABLED  
1kΩ HIGH-Z DISABLED  
1kΩ HIGH-Z ENABLED  
–110  
–115  
–120  
–125  
ADA4077-1 HIGH-Z DISABLED  
ADA4077-1 HIGH-Z ENABLED  
ADA4610-1 HIGH-Z DISABLED  
ADA4610-1 HIGH-Z ENABLED  
1
10  
INPUT FREQUENCY (kHz)  
20  
260kHz  
1.3kΩ  
470pF  
498kHz  
680Ω  
470pF  
1.3MHz  
680Ω  
180pF  
2.27MHz  
390Ω  
180pF  
4.42MHz  
200Ω  
180pF  
Figure 43. THD vs. Input Frequency for Various Source Impedances,  
VDD = 1.8 V, VIO = 3.3 V, VREF = 5 V, 25°C  
RC FILTER BANDWIDTHS (Hz), RESISTOR (Ω), CAPACITOR (pF)  
Figure 45. THD vs. RC Filter Bandwidths for Various Precision ADC Drivers,  
fIN = 1 kHz (Turbo Mode On, High-Z Enabled/Disabled), VDD = 1.8 V,  
VIO = 3.3 V, VREF = 5 V, 25°C  
Figure 44 and Figure 45 show the AD4001/AD4005 SNR and  
THD performance using the ADA4077-1 (supply current per  
amplifier (ISY) = 400 µA) and ADA4610-1 (ISY = 1.50 mA)  
precision amplifiers when driving the AD4001/AD4005 at full  
throughput for high-Z mode enabled and disabled with various  
RC filter values. These amplifiers achieve 93 dB to 96 dB typical  
SNR and better than −110 dB THD with high-Z mode enabled.  
THD is approximately 10 dB better with high-Z mode enabled,  
even for large R values. SNR maintains close to 96 dB, even with a  
very low RC bandwidth cutoff.  
Long Acquisition Phase  
The AD4001/AD4005 also feature a very fast conversion time of  
290 ns, which results in a long acquisition phase. The acquisition is  
further extended by a key feature of the AD4001/AD4005: the  
ADC returns to the acquisition phase typically 100 ns before the  
end of the conversion. This feature provides an even longer time  
for the ADC to acquire the new input voltage. A longer acquisition  
phase reduces the settling requirement on the driving amplifier,  
and a lower power/bandwidth amplifier can be chosen. The longer  
acquisition phase means that a lower RC filter (represented by R  
and C in Figure 32 to Figure 35) cutoff can be used, which means  
a noisier amplifier can also be tolerated. A larger value of R can  
be used in the RC filter with a corresponding smaller value of C,  
reducing amplifier stability concerns without affecting distortion  
performance significantly. A larger value of R also results in  
reduced dynamic power dissipation in the amplifier.  
When high-Z mode is enabled, the ADC consumes approximately  
2 mW per MSPS extra power; however, this power is still  
significantly lower than using dedicated ADC drivers like the  
ADA4807-1. For any system, the front end usually limits the  
overall ac/dc performance of the signal chain. It is evident from  
the data sheets of the selected precision amplifiers, shown in  
Figure 44 and Figure 45, that their own noise and distortion  
performance dominates the SNR and THD specification at a  
certain input frequency.  
See Table 10 for details on setting the RC filter bandwidth and  
choosing a suitable amplifier.  
97  
94  
91  
88  
85  
82  
VOLTAGE REFERENCE INPUT  
A 10 µF (X7R, 0805 size) ceramic chip capacitor is appropriate  
for the optimum performance of the reference input.  
For higher performance and lower drift, use a reference such as  
the ADR4550. Use a low power reference such as the ADR3450  
at the expense of a slight decrease in the noise performance. It is  
recommended to use a reference buffer, such as the ADA4807-1,  
between the reference and the ADC reference input. It is important  
to consider the optimum capacitance necessary to keep the  
reference buffer stable as well as to meet the minimum ADC  
requirement previously stated in this section (that is, a 10 µF  
ceramic chip capacitor, CREF).  
79  
ADA4077-1 HIGH-Z DISABLED  
ADA4077-1 HIGH-Z ENABLED  
ADA4610-1 HIGH-Z DISABLED  
ADA4610-1 HIGH-Z ENABLED  
76  
73  
260kHz  
1.3kΩ  
470pF  
498kHz  
680Ω  
470pF  
1.3MHz  
680Ω  
180pF  
2.27MHz  
390Ω  
180pF  
4.42MHz  
200Ω  
180pF  
RC FILTER BANDWIDTHS (Hz), RESISTOR (Ω), CAPACITOR (pF)  
POWER SUPPLY  
Figure 44. SNR vs. RC Filter Bandwidths for Various Precision ADC Drivers,  
fIN = 1 kHz (Turbo Mode On, High-Z Enabled/Disabled), VDD = 1.8 V,  
VIO = 3.3 V, VREF = 5 V, 25°C  
The AD4001/AD4005 use two power supply pins: a core supply  
(VDD) and a digital input/output interface supply (VIO). VIO  
allows direct interface with any logic between 1.8 V and 5.5 V.  
Rev. B | Page 24 of 37  
 
 
 
 
 
Data Sheet  
AD4001/AD4005  
To reduce the number of supplies needed, VIO and VDD can be  
tied together for 1.8 V operation. The ADP7118 low noise, CMOS,  
low dropout (LDO) linear regulator is recommended to power  
the VDD and VIO pins. The AD4001/AD4005 are independent  
of power supply sequencing between VIO and VDD. Additionally,  
the AD4001/AD4005 are insensitive to power supply variations  
over a wide frequency range, as shown in Figure 46.  
80  
interface. A 3-wire interface using the CNV, SCK, and SDO  
signals minimizes wiring connections, which is useful, for  
instance, in isolated applications. A 4-wire interface using the  
SDI, CNV, SCK, and SDO signals allows CNV, which initiates the  
conversions, to be independent of the readback timing (SDI).  
This interface is useful in low jitter sampling or simultaneous  
sampling applications.  
The AD4001/AD4005 provide a daisy-chain feature using the SDI  
input for cascading multiple ADCs on a single data line, similar  
to a shift register.  
75  
70  
65  
60  
55  
50  
The mode in which the device operates depends on the SDI  
CS  
level when the CNV rising edge occurs.  
mode is selected if  
SDI is high, and daisy-chain mode is selected if SDI is low. The  
SDI hold time is such that when SDI and CNV are connected  
together, daisy-chain mode is always selected.  
In either 3-wire or 4-wire mode, the AD4001/AD4005 offer the  
option of forcing a start bit in front of the data bits. This start  
bit can be used as a busy signal indicator to interrupt the digital  
host and trigger the data reading. Otherwise, without a busy  
indicator, the user must time out the maximum conversion time  
prior to readback.  
100  
1k  
10k  
100k  
1M  
FREQUENCY (Hz)  
Figure 46. PSRR vs. Frequency, VDD = 1.8 V, VIO = 3.3 V, VREF = 5 V, 25°C  
CS  
The busy indicator feature is enabled in  
is low when the ADC conversion ends.  
mode if CNV or SDI  
The AD4001/AD4005 power down automatically at the end of  
each conversion phase; therefore, the power scales linearly with  
the sampling rate. This feature makes the device ideal for low  
sampling rates (even a few samples per second) and battery-  
powered applications. Figure 47 shows the AD4001/AD4005  
total power dissipation and individual power dissipation for  
each rail.  
The state of SDO on power-up is either low or high-Z depending  
on the states of CNV and SDI, as shown in in Table 11.  
Table 11. State of SDO on Power-Up  
CNV  
SDI  
SDO  
Low  
Low  
Low  
High-Z  
0
0
1
1
0
1
0
1
100k  
VDD  
VIO  
REF  
TOTAL POWER  
10k  
1k  
The AD4001/AD4005 have turbo mode capability in both 3-wire  
and 4-wire mode. Turbo mode is enabled by writing to the  
configuration register and replaces the busy indicator feature  
when enabled. Turbo mode allows a slower SPI clock rate, making  
interfacing simpler. The maximum throughput of 2 MSPS for the  
AD4001 can be achieved only with turbo mode enabled and a  
minimum SCK rate of 70 MHz.  
100  
10  
1
0.1  
0.01  
POWER DISSIPATION MEASUREMENTS  
APPLY TO EACH PRODUCT OVER ITS  
SPECIFIED THROUGHPUT RANGE.  
The SCK rate must be sufficiently fast to ensure the conversion  
result is clocked out before another conversion initiates. The  
minimum required SCK rate for an application can be derived  
based on the sample period (tCYC), the number of bits that must  
be read (including data and optional status bits), and which  
digital interface mode is used. Timing diagrams and explanations  
for each digital interface mode are given in the digital modes of  
10  
100  
1k  
10k  
100k  
1M 2M  
THROUGHPUT (SPS)  
Figure 47. Power Dissipation vs. Throughput, VDD = 1.8 V, VIO = 1.8 V,  
VREF = 5 V, 25°C  
DIGITAL INTERFACE  
Although the AD4001/AD4005 have a reduced number of pins,  
they offer flexibility in their serial interface modes. The AD4001/  
AD4005 can also be programmed via 16-bit SPI writes to the  
configuration registers.  
CS  
operation sections (see the Mode, 3-Wire Turbo Mode section  
through the Daisy-Chain Mode section).  
Status bits can also be clocked out at the end of the conversion  
data if the status bits are enabled in the configuration register.  
There are six status bits in total, as described in Table 12.  
CS  
When in  
mode, the AD4001/AD4005 are compatible with  
SPI, QSPI™, MICROWIRE®, digital hosts, and DSPs. In this  
mode, the AD4001/AD4005 can use either a 3-wire or 4-wire  
Rev. B | Page 25 of 37  
 
 
 
 
AD4001/AD4005  
Data Sheet  
The AD4001/AD4005 are configured by 16-bit SPI writes to the  
desired configuration register. The 16-bit word can be written  
via the SDI line while CNV is held low. The 16-bit word consists  
of an 8-bit header and 8-bit register data. For isolated systems,  
the ADuM141D is recommended, which can support the 70 MHz  
SCK rate required to run the AD4001 at its full throughput of  
2 MSPS.  
Table 13. Command Register  
Bit 7  
Bit 6  
Bit 5  
Bit 4  
Bit 3  
Bit 2  
Bit 1  
Bit 0  
WEN  
R/W  
0
1
0
1
0
0
All register read/writes must occur while CNV is low. Data on  
SDI is clocked in on the rising edge of SCK. Data on SDO is  
clocked out on the falling edge of SCK. At the end of the data  
transfer, SDO is put in a high impedance state on the rising  
edge of CNV if daisy-chain mode is not enabled. If daisy-chain  
mode is enabled, SDO goes low on the rising edge of CNV.  
Register reads are not allowed in daisy-chain mode.  
REGISTER READ/WRITE FUNCTIONALITY  
The AD4001/AD4005 register bits are programmable, and their  
default statuses are shown in Table 12. The register map is shown in  
OV  
Table 14. The overvoltage clamp flag ( ) is a read only sticky bit,  
A register write requires three signal lines: SCK, CNV, and SDI.  
During a register write, to read the current conversion results  
on SDO, the CNV pin must be brought low after the conversion  
is completed; otherwise, the conversion results may be incorrect  
on SDO. However, the register write occurs regardless.  
and it is cleared only if the register is read and the overvoltage  
condition is no longer present. It gives an indication of overvoltage  
condition when it is set to 0.  
Table 12. Register Bits  
The LSB of each configuration register is reserved because a  
user reading 16-bit conversion data may be limited to a 16-bit  
SPI frame. The state of SDI on the last bit in the SDI frame may  
be the state that then persists when CNV rises. Because interface  
mode is partly set based on the SDI state when CNV rises, in  
this scenario, the user may need to set the final SDI state.  
Register Bits  
Default Status  
Overvoltage (OV) Clamp Flag 1 bit, 1 = inactive (default)  
Span Compression  
High-Z Mode  
Turbo Mode  
1 bit, 0 = disabled (default)  
1 bit, 0 = disabled (default)  
1 bit, 0 = disabled (default)  
1 bit, 0 = disabled (default)  
Enable Six Status Bits  
The timing diagrams in Figure 48 through Figure 50 show how  
data is read and written when the AD4001/AD4005 are configured  
in register read, write, and daisy-chain mode.  
All access to the register map must start with a write to the 8-bit  
command register in the SPI interface block. The AD4001/AD4005  
ignore all 1s until the first 0 is clocked in; the value loaded into  
the command register is always a 0 followed by seven command  
bits. This command determines whether that operation is a write  
or a read. The AD4001/AD4005 command register is shown in  
Table 13.  
Table 14. Register Map  
ADDR[1:0] Bit 7  
Bit 6  
Reserved Reserved Reserved Enable six Span  
status bits compression  
Bit 5  
Bit 4  
Bit 3  
Bit 2  
Bit 1  
Bit 0  
Reset  
0x0  
High-Z  
mode  
Turbo  
mode  
Overvoltage (OV) clamp  
flag (read only sticky bit)  
0xE1  
tCYC  
tCNVH  
tSCK  
CNV  
SCK  
tSCNVSCK  
tSCKL  
1
2
3
4
5
6
7
8
9
10  
11  
12  
13  
14  
15  
16  
tHSDISCK  
tSSDISCK  
tSCKH  
ADDR[1:0]  
SDI  
1
0
0
0
0
1
WEN  
0
R/W  
1
1
0
0
1
1
tHSDO  
tDSDO  
tEN  
tDIS  
D16  
B3  
SDO  
D17  
D13  
D12  
D15  
D14  
D11  
D10  
B7  
B6  
B5  
B4  
B2  
B1  
B0  
X
Figure 48. Register Read Timing Diagram (X Means Don’t Care)  
Rev. B | Page 26 of 37  
 
 
 
 
 
Data Sheet  
AD4001/AD4005  
tCYC  
tSCK  
1
tCNVH  
tHCNVSCK  
CNV  
tSCNVSCK  
tSCKL  
SCK  
1
2
3
4
5
9
10  
11  
12  
13  
14  
15  
16  
tHSDISCK  
tSCKH  
tSSDISCK  
1
SDI  
1
WEN  
R/W  
0
0
0
1
1
0
0
1
ADDR[1:0]  
B7  
B6  
B5  
B4  
B3  
B2  
B1  
B0  
0
1
0
0
tHSDO  
tDSDO  
EN  
D8  
D7  
SDO  
1
D15  
D14  
D13  
D12  
D11  
D10  
D9  
D6  
D5  
D4  
D3  
D2  
D1  
D0  
CONVERSION RESULT ON D[15:0]  
THE USER MUST WAIT tCONV WHEN READING BACK THE CONVERSION RESULT AND PERFORMING A REGISTER WRITE AT THE SAME TIME.  
Figure 49. Register Write Timing Diagram  
tCYC  
tCNVH  
tSCK  
CNV  
SCK  
tSCNVSCK  
tSCKL  
1
24  
tSCKH  
SDI  
0
A
0
COMMAND (0x14)  
DATA (0xAB)  
SDO /SDI  
A
0
COMMAND (0x14)  
DATA (0xAB)  
0
B
tDIS  
SDO  
B
0
COMMAND (0x14)  
0
Figure 50. Register Write Timing Diagram, Daisy-Chain Mode  
Rev. B | Page 27 of 37  
 
AD4001/AD4005  
Data Sheet  
The SDO line goes to high-Z after the sixth status bit is clocked  
out (except in daisy-chain mode). The user is not required to  
clock out all status bits to start the next conversion. The serial  
STATUS WORD  
The 6-bit status word can be appended to the end of a conversion  
result, and the default conditions of these bits are shown in  
Table 15. The status bits must be enabled in the register setting.  
CS  
interface timing for  
mode, 3-wire without busy indicator,  
including status bits, is shown in Figure 51.  
OV  
When the overvoltage clamp flag ( ) is a 0, it indicates an  
overvoltage condition. The overvoltage clamp flag status bit  
updates on a per conversion basis.  
Table 15. Status Bits (Default Conditions)  
Bit 5  
Bit 4  
Bit 3  
Bit 2  
Bit 1  
Bit 0  
Overvoltage (OV) clamp flag  
Span compression  
High-Z mode  
Turbo mode  
Reserved  
Reserved  
SDI = 1  
tCYC  
tCNVH  
CN V  
ACQ  
ACQUISITION  
CONVERSION  
tCONV  
ACQUISITION  
tSCK  
tQUIET2  
tSCKL  
SCK  
20  
21  
22  
16  
1
2
3
14  
tSCKH  
15  
t
HSDO  
tEN  
tDSDO  
D13  
tDIS  
SDO  
D15  
D14  
D1  
D0  
B1  
B0  
STATUS BITS B[5:0]  
CS  
Figure 51. Mode, 3-Wire Without Busy Indicator Serial Interface Timing Diagram, Including Status Bits (SDI High)  
Rev. B | Page 28 of 37  
 
 
 
Data Sheet  
AD4001/AD4005  
When SDI is forced high, a rising edge on CNV initiates a  
CS MODE, 3-WIRE TURBO MODE  
conversion. The previous conversion data is available to read  
after the CNV rising edge. The user must wait tQUIET1 time after  
CNV is brought high before bringing CNV low to clock out the  
previous conversion result. The user must also wait tQUIET2 time  
after the last falling edge of SCK to when CNV is brought high.  
This mode is typically used when a single AD4001/AD4005  
device is connected to an SPI-compatible digital host. It provides  
additional time during the end of the ADC conversion process  
to clock out the previous conversion result, providing a lower  
SCK rate. The AD4001 can achieve a throughput rate of 2 MSPS  
only when turbo mode is enabled and using a minimum SCK  
rate of 70 MHz. With turbo mode enabled, the AD4005 can also  
achieve its maximum throughput rate of 1 MSPS with a  
minimum SCK rate of 22 MHz. The connection diagram is  
shown in Figure 52, and the corresponding timing diagram is  
shown in Figure 53.  
When the conversion is complete, the AD4001/AD4005 enter  
the acquisition phase and power down. When CNV goes low,  
the MSB is output to SDO. The remaining data bits are clocked  
by subsequent SCK falling edges. The data is valid on both SCK  
edges. Although the rising edge can capture the data, a digital  
host using the SCK falling edge allows a faster reading rate,  
provided it has an acceptable hold time. After the 16th SCK  
falling edge or when CNV goes high (whichever occurs first),  
SDO returns to high impedance.  
This mode replaces the 3-wire with busy indicator mode by  
programming the turbo mode bit, Bit 1 (see Table 14).  
CONVERT  
DIGITAL HOST  
CNV  
VIO  
AD4001/  
AD4005  
SDI  
SDO  
DATA IN  
SCK  
CLK  
CS  
Figure 52. Mode, 3-Wire Turbo Mode Connection Diagram (SDI High)  
SDI = 1  
tCYC  
CNV  
t
ACQ  
ACQUISITION  
CONVERSION  
CONV  
ACQUISITION  
tSCK  
tSCKL  
QUIET2  
tQUIET1  
SCK  
SDO  
1
2
3
14  
15  
16  
tSCKH  
tHSDO  
tEN  
tDSDO  
tDIS  
D15  
D14  
D13  
D1  
D0  
CS  
Figure 53. Mode, 3-Wire Turbo Mode Serial Interface Timing Diagram (SDI High)  
Rev. B | Page 29 of 37  
 
 
 
AD4001/AD4005  
Data Sheet  
When the conversion is complete, the AD4001/AD4005 enter  
the acquisition phase and power down. When CNV goes low,  
the MSB is output onto SDO. The remaining data bits are clocked  
by subsequent SCK falling edges. The data is valid on both SCK  
edges. Although the rising edge can capture the data, a digital  
host using the SCK falling edge allows a faster reading rate,  
provided it has an acceptable hold time. After the 16th SCK  
falling edge or when CNV goes high (whichever occurs first),  
SDO returns to high impedance.  
CS MODE, 3-WIRE WITHOUT BUSY INDICATOR  
This mode is typically used when a single AD4001/AD4005 is  
connected to an SPI-compatible digital host. The connection  
diagram is shown in Figure 54, and the corresponding timing  
diagram is shown in Figure 55.  
With SDI tied to VIO, a rising edge on CNV initiates a conversion,  
CS  
selects the  
mode, and forces SDO to high impedance. After a  
conversion is initiated, it continues until completion irrespective  
of the state of CNV. This feature can be useful, for instance, to  
bring CNV low to select other SPI devices, such as analog  
multiplexers; however, CNV must be returned high before the  
minimum conversion time elapses and then held high for the  
maximum possible conversion time to avoid the generation of  
the busy signal indicator.  
There must not be any digital activity on SCK during the  
conversion.  
CONVERT  
DIGITAL HOST  
CNV  
VIO  
AD4001/  
AD4005  
SDI  
SDO  
DATA IN  
SCK  
CLK  
CS  
Figure 54. Mode, 3-Wire Without Busy Indicator Connection Diagram (SDI High)  
SDI = 1  
tCYC  
tCNVH  
CNV  
tACQ  
ACQUISITION  
CONVERSION  
tCONV  
ACQUISITION  
tSCK  
tSCKL  
tQUIET2  
SCK  
1
2
3
14  
15  
16  
tSCKH  
HSDO  
tEN  
tDSDO  
tDIS  
SDO  
D15  
D14  
D13  
D1  
D0  
CS  
Figure 55. Mode, 3-Wire Without Busy Indicator Serial Interface Timing Diagram (SDI High)  
Rev. B | Page 30 of 37  
 
 
 
Data Sheet  
AD4001/AD4005  
When the conversion is complete, SDO goes from high  
CS MODE, 3-WIRE WITH BUSY INDICATOR  
impedance to low impedance. With a pull-up resistor of 1 kΩ  
on the SDO line, this transition can be used as an interrupt  
signal to initiate the data reading controlled by the digital host.  
The AD4001/AD4005 then enter the acquisition phase and  
power down. The data bits are then clocked out, MSB first, by  
subsequent SCK falling edges. The data is valid on both SCK edges.  
Although the rising edge can capture the data, a digital host  
using the SCK falling edge allows a faster reading rate, provided  
it has an acceptable hold time. After the optional 17th SCK  
falling edge or when CNV goes high (whichever occurs first),  
SDO returns to high impedance.  
This mode is typically used when a single AD4001/AD4005 is  
connected to an SPI-compatible digital host with an interrupt  
IRQ  
input (  
).  
The connection diagram is shown in Figure 56, and the  
corresponding timing diagram is shown in Figure 57.  
With SDI tied to VIO, a rising edge on CNV initiates a conversion,  
CS  
selects the  
mode, and forces SDO to high impedance. SDO  
is maintained in high impedance until the completion of the  
conversion irrespective of the state of CNV. Prior to the minimum  
conversion time, CNV can select other SPI devices, such as  
analog multiplexers; however, CNV must be returned low  
before the minimum conversion time elapses and then held  
low for the maximum possible conversion time to guarantee  
the generation of the busy signal indicator.  
If multiple AD4001/AD4005 devices are selected at the same  
time, the SDO output pin handles this contention without  
damage or induced latch-up. Meanwhile, it is recommended  
to keep this contention as short as possible to limit extra power  
dissipation.  
There must not be any digital activity on the SCK during the  
conversion.  
CONVERT  
VIO  
1k  
DIGITAL HOST  
CNV  
VIO  
AD4001/  
SDI  
SDO  
DATA IN  
AD4005  
IRQ  
SCK  
CLK  
CS  
Figure 56. Mode, 3-Wire with Busy Indicator Connection Diagram (SDI High)  
SDI = 1  
tCYC  
tCNVH  
CNV  
tACQ  
ACQUISITION  
CONVERSION  
tCONV  
ACQUISITION  
tSCK  
tSCKL  
tQUIET2  
SCK  
SDO  
1
2
3
15  
16  
17  
tHSDO  
tSCKH  
tDSDO  
tDIS  
D15  
D14  
D1  
D0  
CS  
Figure 57. Mode, 3-Wire with Busy Indicator Serial Interface Timing Diagram (SDI High)  
Rev. B | Page 31 of 37  
 
 
 
AD4001/AD4005  
Data Sheet  
rising edge. The user must wait tQUIET1 time after CNV is brought  
high before bringing SDI low to clock out the previous conversion  
result. The user must also wait tQUIET2 time after the last falling  
edge of SCK to when CNV is brought high.  
CS MODE, 4-WIRE TURBO MODE  
This mode is typically used when a single AD4001/AD4005  
device is connected to an SPI-compatible digital host. It provides  
additional time during the end of the ADC conversion process  
to clock out the previous conversion result, giving a lower SCK  
rate. The AD4001 can achieve a throughput rate of 2 MSPS only  
when turbo mode is enabled and using a minimum SCK rate of  
70 MHz. With turbo mode enabled, the AD4005 can also achieve  
its maximum throughput rate of 1 MSPS with a minimum SCK  
rate of 22 MHz. The connection diagram is shown in Figure 58,  
and the corresponding timing diagram is shown in Figure 59.  
When the conversion is complete, the AD4001/AD4005 enter  
the acquisition phase and power down. The ADC result can be  
read by bringing its SDI input low, which consequently outputs  
the MSB onto SDO. The remaining data bits are then clocked by  
subsequent SCK falling edges. The data is valid on both SCK  
edges. Although the rising edge can capture the data, a digital  
host using the SCK falling edge allows a faster reading rate,  
provided it has an acceptable hold time. After the 16th SCK  
falling edge or when SDI goes high (whichever occurs first),  
SDO returns to high impedance.  
This mode replaces the 4-wire with busy indicator mode by  
programming the turbo mode bit, Bit 1 (see Table 14).  
With SDI high, a rising edge on CNV initiates a conversion.  
The previous conversion data is available to read after the CNV  
CS1  
CONVERT  
VIO  
1k  
DIGITAL HOST  
CNV  
AD4001/  
SDI  
SDO  
DATA IN  
IRQ  
AD4005  
SCK  
CLK  
CS  
Figure 58. Mode, 4-Wire Turbo Mode Connection Diagram  
CNV  
tCYC  
tSSDICNV  
SDI  
tHSDICNV  
tACQ  
ACQUISITION  
CONVERSION  
tCONV  
ACQUISITION  
tSCK  
tSCKL  
tQUIET2  
tQUIET1  
SCK  
1
2
3
14  
15  
16  
tHSDO  
tSCKH  
tDIS  
tEN  
tDSDO  
SDO  
D15  
D14  
D13  
D1  
D0  
CS  
Figure 59. Mode, 4-Wire Turbo Mode Timing Diagram  
Rev. B | Page 32 of 37  
 
 
 
Data Sheet  
AD4001/AD4005  
When the conversion is complete, the AD4001/AD4005 enter  
the acquisition phase and power down. Each ADC result can be  
read by bringing its SDI input low, which consequently outputs  
the MSB onto SDO. The remaining data bits are then clocked by  
subsequent SCK falling edges. The data is valid on both SCK  
edges. Although the rising edge can capture the data, a digital  
host using the SCK falling edge allows a faster reading rate,  
provided it has an acceptable hold time. After the 16th SCK falling  
edge or when SDI goes high (whichever occurs first), SDO returns  
to high impedance and another AD4001/AD4005 can be read.  
CS MODE, 4-WIRE WITHOUT BUSY INDICATOR  
This mode is typically used when multiple AD4001/AD4005  
devices are connected to an SPI-compatible digital host.  
A connection diagram example using two AD4001/AD4005  
devices is shown in Figure 60, and the corresponding timing  
diagram is shown in Figure 61.  
With SDI high, a rising edge on CNV initiates a conversion,  
CS  
selects the  
mode, and forces SDO to high impedance. In this  
mode, CNV must be held high during the conversion phase and  
the subsequent data readback. If SDI and CNV are low, SDO is  
driven low. Prior to the minimum conversion time, SDI can select  
other SPI devices, such as analog multiplexers; however, SDI  
must be returned high before the minimum conversion time  
elapses and then held high for the maximum possible conversion  
time to avoid the generation of the busy signal indicator.  
CS2  
CS1  
CONVERT  
CNV  
CNV  
DIGITAL HOST  
AD4001/  
AD4001/  
AD4005  
SDI  
SDO  
SDI  
SDO  
AD4005  
DEVICE A  
SCK  
DEVICE B  
SCK  
DATA IN  
CLK  
CS  
Figure 60. Mode, 4-Wire Without Busy Indicator Connection Diagram  
CYC  
CNV  
tACQ  
ACQUISITION  
CONVERSION  
tCONV  
ACQUISITION  
tQUIET2  
tSSDICNV  
SDI(CS1)  
tHSDICNV  
SDI(CS2)  
SCK  
tSCK  
tSCKL  
1
2
3
14  
15  
16  
17  
18  
30  
31  
32  
tHSDO  
t
SCKH  
tDSDO  
D13  
tDIS  
tEN  
SDO  
D15  
D14  
D1  
D0  
D15  
D14  
D1  
D0  
CS  
Figure 61. Mode, 4-Wire Without Busy Indicator Serial Interface Timing Diagram  
Rev. B | Page 33 of 37  
 
 
 
AD4001/AD4005  
Data Sheet  
SDI must be returned low before the minimum conversion time  
elapses and then held low for the maximum possible conversion  
time to guarantee the generation of the busy signal indicator.  
CS MODE, 4-WIRE WITH BUSY INDICATOR  
This mode is typically used when a AD4001/AD4005 device is  
connected to an SPI-compatible digital host with an interrupt  
When the conversion is complete, SDO goes from high  
impedance to low impedance. With a pull-up resistor of 1 kΩ  
on the SDO line, this transition can be used as an interrupt signal  
to initiate the data readback controlled by the digital host. The  
AD4001/AD4005 then enter the acquisition phase and power  
down. The data bits are then clocked out, MSB first, by subsequent  
SCK falling edges. The data is valid on both SCK edges. Although  
the rising edge can capture the data, a digital host using the SCK  
falling edge allows a faster reading rate, provided it has an  
acceptable hold time. After the optional 17th SCK falling edge or  
when SDI goes high (whichever occurs first), SDO returns to  
high impedance.  
IRQ  
input (  
), and when it is desired to keep CNV, which samples  
the analog input, independent of the signal used to select the  
data reading. This independence is particularly important in  
applications where low jitter on CNV is desired.  
The connection diagram is shown in Figure 62, and the  
corresponding timing diagram is shown in Figure 63.  
With SDI high, a rising edge on CNV initiates a conversion,  
CS  
selects the  
mode, and forces SDO to high impedance. In this  
mode, CNV must be held high during the conversion phase and  
the subsequent data readback. If SDI and CNV are low, SDO is  
driven low. Prior to the minimum conversion time, SDI can  
select other SPI devices, such as analog multiplexers; however,  
CS1  
CONVERT  
VIO  
1k  
DIGITAL HOST  
CNV  
AD4001/  
SDI  
SDO  
DATA IN  
IRQ  
AD4005  
SCK  
CLK  
CS  
Figure 62. Mode, 4-Wire with Busy Indicator Connection Diagram  
tCYC  
CNV  
tACQ  
ACQUISITION  
CONVERSION  
tCONV  
ACQUISITION  
tQUIET2  
tSSDICNV  
SDI  
tSCK  
tHSDICNV  
tSCKL  
SCK  
SDO  
1
2
3
15  
16  
17  
tSCKH  
tHSDO  
tDSDO  
tDIS  
tEN  
D15  
D14  
D1  
D0  
CS  
Figure 63. Mode, 4-Wire with Busy Indicator Serial Interface Timing Diagram  
Rev. B | Page 34 of 37  
 
 
 
Data Sheet  
AD4001/AD4005  
the daisy-chain outputs its data MSB first, and 16 × N clocks are  
required to read back the N ADCs. The data is valid on both  
SCK edges. The maximum conversion rate is reduced because of  
the total readback time.  
DAISY-CHAIN MODE  
Use this mode to daisy-chain multiple AD4001/AD4005 devices  
on a 3-wire or 4-wire serial interface. This feature is useful for  
reducing component count and wiring connections, for example,  
in isolated multiconverter applications or for systems with a  
limited interfacing capacity. Data readback is analogous to  
clocking a shift register.  
It is possible to write to each ADC register in daisy-chain mode.  
The timing diagram is shown in Figure 50. This mode requires  
4-wire operation because data is clocked in on the SDI line with  
CNV held low. The same command byte and register data can  
be shifted through the entire chain to program all ADCs in the  
chain with the same register contents, which requires 8 × (N + 1)  
clocks for N ADCs. It is possible to write different register  
contents to each ADC in the chain by writing to the furthest ADC  
in the chain, first using 8 × (N + 1) clocks, and then the second  
furthest ADC with 8 × N clocks, and so forth until reaching the  
nearest ADC in the chain, which requires 16 clocks for the  
command and register data. It is not possible to read register  
contents in daisy-chain mode; however, the six status bits can be  
enabled if the user wants to determine the ADC configuration.  
Note that enabling the status bits requires six extra clocks to clock  
out the ADC result and the status bits per ADC in the chain.  
Turbo mode cannot be used in daisy-chain mode.  
A connection diagram example using two AD4001/AD4005  
devices is shown in Figure 64, and the corresponding timing  
diagram is shown in Figure 65.  
When SDI and CNV are low, SDO is driven low. With SCK low,  
a rising edge on CNV initiates a conversion, selects daisy-chain  
mode, and disables the busy indicator. In this mode, CNV is held  
high during the conversion phase and the subsequent data  
readback. When the conversion is complete, the MSB is output  
onto SDO, and the AD4001/AD4005 enter the acquisition phase  
and power down. The remaining data bits stored in the internal  
shift register are clocked out of SDO by subsequent SCK falling  
edges. For each ADC, SDI feeds the input of the internal shift  
register and is clocked by the SCK rising edges. Each ADC in  
CONVERT  
CNV  
CNV  
DIGITAL HOST  
DATA IN  
AD4001/  
AD4001/  
AD4005  
SDI  
SDO  
SDI  
SDO  
AD4005  
DEVICE A  
SCK  
DEVICE B  
SCK  
CLK  
Figure 64. Daisy-Chain Mode Connection Diagram  
SDI = 0  
A
tCYC  
CNV  
tACQ  
ACQUISITION  
CONVERSION  
tCONV  
ACQUISITION  
tSCK  
tQUIET2  
tSCKL  
t
QUIET2  
SCK  
1
2
3
14  
15  
16  
17  
18  
30  
31  
32  
tSSDISCK  
tSCKH  
tHSCKCNV  
tHSDISCK  
tEN  
D
D
15  
D
14  
D
13  
13  
D
A
1
1
D
0
SDO = SDI  
A
A
A
A
A
B
tHSDO  
tDIS  
t
DSDO  
D
15  
D
14  
D
1
D 0  
A
15  
D
14  
D
D
B
D
0
SDO  
A
A
A
B
B
B
B
B
Figure 65. Daisy-Chain Mode Serial Interface Timing Diagram  
Rev. B | Page 35 of 37  
 
 
 
AD4001/AD4005  
Data Sheet  
LAYOUT GUIDELINES  
The PCB that houses the AD4001/AD4005 must be designed so  
that the analog and digital sections are separated and confined to  
certain areas of the board. The pinout of the AD4001/AD4005,  
with its analog signals on the left side and its digital signals on  
the right side, eases this task.  
Avoid running digital lines under the device because they couple  
noise onto the die, unless a ground plane under the AD4001/  
AD4005 is used as a shield. Fast switching signals, such as CNV  
or clocks, must not run near analog signal paths. Avoid crossover  
of digital and analog signals.  
At least one ground plane must be used. It can be common or  
split between the digital and analog sections. In the latter case,  
join the planes underneath the AD4001/AD4005 devices.  
Figure 67. Example Layout of the AD4001 (Bottom Layer)  
EVALUATING THE AD4001/AD4005 PERFORMANCE  
The AD4001/AD4005 voltage reference input (REF) has a  
dynamic input impedance. Decouple the REF pin with minimal  
parasitic inductances by placing the reference decoupling ceramic  
capacitor close to (ideally right up against) the REF and GND  
pins and connect them with wide, low impedance traces.  
Other recommended layouts for the AD4001/AD4005 are  
outlined in the user guide of the evaluation board for the AD4001  
(EVAL-AD4001FMCZ). The evaluation board package includes  
a fully assembled and tested evaluation board with the AD4001  
documentation, and software for controlling the board from a  
PC via the EVAL-SDP-CH1Z. The EVAL-AD4001FMCZ can  
also be used to evaluate the AD4005 by limiting the throughput  
to 1 MSPS in its software (see UG-1042).  
Finally, decouple the VDD and VIO power supplies of the  
AD4001/AD4005 with ceramic capacitors, typically 0.1 µF,  
placed close to the AD4001/AD4005 and connected using short,  
wide traces to provide low impedance paths and to reduce the  
effect of glitches on the power supply lines.  
An example of the AD4001 layout following these rules is shown in  
Figure 66 and Figure 67. Note that the AD4005 layout is equivalent  
to the AD4001 layout.  
Figure 66. Example Layout of the AD4001 (Top Layer)  
Rev. B | Page 36 of 37  
 
 
 
 
Data Sheet  
AD4001/AD4005  
OUTLINE DIMENSIONS  
3.10  
3.00  
2.90  
10  
1
6
5
5.15  
4.90  
4.65  
3.10  
3.00  
2.90  
PIN 1  
IDENTIFIER  
0.50 BSC  
0.95  
0.85  
0.75  
15° MAX  
1.10 MAX  
0.70  
0.55  
0.40  
0.15  
0.05  
0.23  
0.13  
6°  
0°  
0.30  
0.15  
COPLANARITY  
0.10  
COMPLIANT TO JEDEC STANDARDS MO-187-BA  
Figure 68. 10-Lead Mini Small Outline Package [MSOP]  
(RM-10)  
Dimensions shown in millimeters  
DETAIL A  
(JEDEC 95)  
2.48  
2.38  
2.23  
3.10  
3.00 SQ  
0.50 BSC  
2.90  
10  
6
PIN 1 INDEX  
EXPOSED  
PAD  
1.74  
1.64  
1.49  
AREA  
0.50  
0.40  
0.30  
0.20 MIN  
1
5
PIN  
1
BOTTOM VIEW  
TOP VIEW  
SIDE VIEW  
INDIC ATOR AREA OPTIONS  
(SEE DETAIL A)  
FOR PROPER CONNECTION OF  
THE EXPOSED PAD, REFER TO  
THE PIN CONFIGURATION AND  
FUNCTION DESCRIPTIONS  
0.80  
0.75  
0.70  
0.05 MAX  
0.02 NOM  
COPLANARITY  
0.08  
SECTION OF THIS DATA SHEET.  
SEATING  
PLANE  
0.30  
0.25  
0.20  
0.20 REF  
Figure 69. 10-Lead Lead Frame Chip Scale Package [LFCSP]  
3 mm × 3 mm Body and 0.75 mm Package Height  
(CP-10-9)  
Dimensions shown in millimeters  
ORDERING GUIDE  
Integral  
Nonlinearity (INL)  
Temperature  
Range  
Ordering Package  
Quantity Option  
Model1, 2  
Package Description  
10-Lead LFCSP, Reel  
10-Lead MSOP, Tube  
10-Lead MSOP, Reel  
10-Lead LFCSP, Reel  
10-Lead MSOP, Tube  
10-Lead MSOP, Reel  
Branding  
C8H  
C8H  
AD4001BCPZ-RL7  
AD4001BRMZ  
AD4001BRMZ-RL7  
AD4005BCPZ-RL7  
AD4005BRMZ  
0.4 LSB  
0.4 LSB  
0.4 LSB  
−40°C to +125°C  
−40°C to +125°C  
−40°C to +125°C  
−40°C to +125°C  
−40°C to +125°C  
−40°C to +125°C  
1500  
50  
CP-10-9  
RM-10  
RM-10  
CP-10-9  
RM-10  
RM-10  
1000  
1500  
50  
C8H  
0.4 LSB  
0.4 LSB  
0.4 LSB  
C8T  
C8T  
C8T  
AD4005BRMZ-RL7  
EVAL-AD4001FMCZ  
1000  
AD4001 Evaluation Board  
Compatible with EVAL-SDP-CH1Z  
1 Z = RoHS Compliant Part.  
2 The EVAL-AD4001FMCZ can also be used to evaluate the AD4005 by setting the throughput to 1 MSPS in its software (see UG-1042).  
©2017 Analog Devices, Inc. All rights reserved. Trademarks and  
registered trademarks are the property of their respective owners.  
D15368-0-8/17(B)  
Rev. B | Page 37 of 37  
 
 

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