AD7357_08 [ADI]
Differential Input, Dual, Simultaneous Sampling, 4.2 MSPS, 14-Bit, SAR ADC; 差分输入，双通道，同步采样， 4.2 MSPS ， 14位SAR ADC
| 型号： | AD7357_08 |
| 厂家： | 
ADI |
| 描述： | Differential Input, Dual, Simultaneous Sampling, 4.2 MSPS, 14-Bit, SAR ADC |
| 文件： | 总20页 (文件大小：397K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Differential Input, Dual, Simultaneous
Sampling, 4.2 MSPS, 14-Bit, SAR ADC
Preliminary Technical Data
AD7357
FEATURES
FUNCTIONAL BLOCK DIAGRAM
V
V
DRIVE
DD
Dual 14-bit SAR ADC
Simultaneous sampling
AD7357
Throughput rate: 4.2 MSPS per channel
Specified for VDD of 2.5 V
Power dissipation: 35 mW at 4.2 MSPS
On-chip reference: 2.048 V 0.25%, 6 ppm/°C
Dual conversion with read
V
V
INA+
14-BIT
SUCCESSIVE
APPROXIMATION
ADC
T/H
SDATA
INA–
A
REF
A
BUF
High speed serial interface
SPI-/QSPI-/MICROWIRE-/DSP-compatible
−40°C to +125°C operation
Shutdown mode: 10 µA maximum
16-lead TSSOP package
SCLK
CS
CONTROL
LOGIC
REF
BUF
REF
V
B
14-BIT
SUCCESSIVE
APPROXIMATION
ADC
SDATA
B
INB+
INB–
T/H
V
AGND
AGND
REFGND
DGND
Figure 1.
GENERAL DESCRIPTION
The AD73571 is a dual, 14-bit, high speed, low power, successive
approximation analog-to-digital converter (ADC) that operates
from a single 2.5 V power supply and features throughput rates up
to 4.2 MSPS. The part contains two ADCs, each preceded by a low
noise, wide bandwidth track-and-hold circuit that can handle input
frequencies in excess of 110 MHz.
PRODUCT HIGHLIGHTS
1. Two Complete ADC Functions.
These functions allow simultaneous sampling and
conversion of two channels. The conversion result of both
channels is simultaneously available on separate data lines
or in succession on one data line if only one serial port is
available.
The conversion process and data acquisition use standard control
inputs allowing for easy interfacing to microprocessors or DSPs.
2. High Throughput with Low Power Consumption.
The AD7357 offers a 4.2 MSPS throughput rate with 35
mW power consumption.
CS
The input signal is sampled on the falling edge of ; conversion is
also initiated at this point. The conversion time is determined by
the SCLK frequency.
3. Simultaneous Sampling.
The AD7357 uses advanced design techniques to achieve very low
power dissipation at high throughput rates. With 2.5 V supply and
a 4.2 MSPS throughput rate, the part consumes 14 mA typically.
The part also offers flexible power/throughput rate management
options.
The part features two standard successive approximation
ADCs with accurate control of the sampling instant via a
CS
input and once off conversion control.
Table 1. Related Devices
Generic
AD7356
AD7352
AD7266
AD7866
AD7366
AD7367
Resolution Throughput Analog Input
The analog input range for the part is the differential common
mode +/- VREF/2. The AD7357 has an on-chip 2.048 V reference
that can be overdriven when an external reference is preferred.
12-bit
12-bit
12-bit
12-bit
12-bit
14-bit
5 MSPS
3 MSPS
2 MSPS
1 MSPS
1 MSPS
1 MSPS
Differential
Differential
Differential/Single-Ended
Single-Ended
Single-Ended Bipolar
Single-Ended Bipolar
The AD7357 is available in a 16-lead thin shrink small outline
package (TSSOP).
1 Protected by U.S. Patent No. 6,681,332.
Rev. PrF
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 registeredtrademarks arethe property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
www.analog.com
©2008 Analog Devices, Inc. All rights reserved.
AD7357
Preliminary Technical Data
TABLE OF CONTENTS
Features .............................................................................................. 1
Analog Inputs ............................................................................. 13
Driving Differential Inputs ....................................................... 13
ADC Transfer Function............................................................. 14
Modes of Operation ....................................................................... 15
Normal Mode.............................................................................. 15
Partial Power-Down Mode ....................................................... 15
Full Power-Down Mode ............................................................ 16
Power-Up Times......................................................................... 17
Power vs. Throughput Rate....................................................... 17
Serial Interface ................................................................................ 18
Application Hints ........................................................................... 19
Grounding and Layout .............................................................. 19
Evaluating the AD7357 Performance...................................... 19
Outline Dimensions....................................................................... 20
Ordering Guide .......................................................................... 20
Functional Block Diagram .............................................................. 1
General Description......................................................................... 1
Product Highlights ........................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Timing Specifications .................................................................. 5
Absolute Maximum Ratings............................................................ 6
ESD Caution.................................................................................. 6
Pin Configuration and Function Descriptions............................. 7
Typical Performance Characteristics ............................................. 8
Terminology .................................................................................... 10
Theory of Operation ...................................................................... 12
Circuit Information.................................................................... 12
Converter Operation.................................................................. 12
Analog Input Structure.............................................................. 12
REVISION HISTORY
11/08—Revision PrF
Rev. PrF | Page 2 of 20
Preliminary Technical Data
SPECIFICATIONS
AD7357
VDD = 2.5 ± 10% V, VDRIVE = 2.25 V to 3.6 V, internal reference = 2.048 V, fSCLK = 80 MHz, fSAMPLE = 4.2 MSPS; TA = TMIN to TMAX1, unless
otherwise noted.
Table 2.
Parameter
Min
Typ
Max
Unit
Test Conditions/Comments
DYNAMIC PERFORMANCE
Signal-to-Noise Ratio (SNR)
Signal-to-Noise and Distortion (SINAD)
Total Harmonic Distortion (THD)
Spurious Free Dynamic Range (SFDR)
Intermodulation Distortion (IMD)
Second-Order Terms
Third-Order Terms
ADC-to-ADC Isolation
CMRR
fIN = 1 MHz sine wave
78
77
dB
dB
dB
dB
TBD
TBD
fa = 1 MHz + 50 kHz, fb = 1 MHz – 50 kHz
−84
−76
−100
−100
dB
dB
dB
dB
fIN = 1 MHz, fNOISE = 100 kHz to 2.5 MHz
fNOISE = 100 kHz to 2.5 MHz
SAMPLE AND HOLD
Aperture Delay
Aperture Delay Match
Aperture Jitter
3.5
40
ns
ps
ps
16
Full Power Bandwidth
110
77
MHz
MHz
@ 3 dB
@ 0.1 dB
DC ACCURACY
Resolution
14
Bits
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
Integral Nonlinearity
Differential Nonlinearity
Positive Full-Scale Error
Positive Full-Scale Error Match
Midscale Error
Midscale Error Match
Negative Full-Scale Error
Negative Full-Scale Error Match
ANALOG INPUT
2
0.ꢀꢀ
10
6
10
6
Guaranteed no missed codes to 14 bits
1
1
1
10
6
Fully Differential Input Range (VIN+ and VIN−)
VCM VREF/2
V
V
VCM = common-mode voltage, VIN+ and
VIN− must remain within GND and VDD
The voltage around which VIN+ and VIN−
are centered
Common-Mode Voltage Range
0.5
1.ꢀ
5
DC Leakage Current
Input Capacitance
0.5
32
8
µA
pF
pF
When in track mode
When in hold mode
REFERENCE INPUT/OUTPUT
VREF Input Voltage Range
VREF Input Current
2.048 + 0.1
VDD
V
mA
V
0.3
0.45
2.058
2.053
When in reference overdrive mode
2.048 V 0.5ꢁ max @ VDD = 2.5 V 5ꢁ
2.048 V 0.25ꢁ max @ VDD = 2.5 V 5ꢁ and
25°C
VREF Output Voltage
2.038
2.043
V
VREF Temperature Coefficient
VREF Long Term Stability
VREF Thermal Hysteresis2
VREF Noise
6
20
ppm/°C
ppm
ppm
µV rms
Ω
100
50
60
1
For 1000 hours
When in track
VREF Output Impedance
VREF Input Capacitance
TBD
pF
Rev. PrF | Page 3 of 20
AD7357
Preliminary Technical Data
Parameter
Min
Typ
Max
Unit
Test Conditions/Comments
LOGIC INPUTS
Input High Voltage, VINH
Input Low Voltage, VINL
Input Current, IIN
Input Capacitance, CIN
LOGIC OUTPUTS
0.6 × VDRIVE
V
V
µA
pF
0.3 × VDRIVE
1
VIN = 0 V or VDRIVE
3
Output High Voltage, VOH
Output Low Voltage, VOL
Floating-State Leakage Current
Floating-State Output Capacitance
Output Coding
VDRIVE −0.2
V
V
µA
pF
0.2
1
5.5
Straight Binary
CONVERSION RATE
Conversion Time
t2 + 15 × tSCLK
ns
Track-and-Hold Acquisition Time
Throughput Rate
30
4.2
ns
MSPS
Full-scale step input
POWER REQUIREMENTS
VDD
2.25
2.25
2.75
3.6
V
V
Nominal VDD = 2.5 V
VDRIVE
3
ITOTAL
Digital inputs = 0 V or VDRIVE
Normal Mode (Operational)
Normal Mode (Static)
Partial Power-Down Mode
Full Power-Down Mode
Power Dissipation
14
6
3.5
5
20
7.5
4.5
40
mA
mA
mA
µA
SCLK on or off
SCLK on or off
SCLK on or off
Normal Mode (Operational)
Normal Mode (Static)
Partial Power-Down Mode
Full Power-Down Mode
36
16
ꢀ.5
16
5ꢀ
21
11.5
110
mW
mW
mW
µW
SCLK on or off
SCLK on or off
SCLK on or off
1 Temperature ranges are as follows: Y grade: −40°C to +125°C, B grade: −40°C to +85°C.
2 See the Terminology section.
3 ITOTAL is the total current flowing in VDD and VDRIVE
.
Rev. PrF | Page 4 of 20
Preliminary Technical Data
AD7357
TIMING SPECIFICATIONS
VDD = 2.5 V ± 10%, VDRIVE = 2.25 V to 3.6 V, internal reference = 2.048 V, TA = TMAX to TMIN1, unless otherwise noted.
Table 3.
Parameter
Limit at TMIN, TMAX
Unit
Description
fSCLK
50
80
kHz min
MHz max
ns max
ns min
tCONVERT
tQUIET
t2 + 15 × tSCLK
5
tSCLK = 1/fSCLK
CS
Minimum time between end of serial read and next falling edge of
t2
5
6
ns min
ns max
CS
to SCLK setup time
2
t3
CS
Delay from until SDATAA and SDATAB are three-state disabled
Data access time after SCLK falling edge
1.8 V ≤ VDRIVE < 2.25 V
2, 3
t4
12.5
11
ꢀ.5
ꢀ
5
5
3.5
ꢀ.5
5
ns max
ns max
ns max
ns max
ns min
ns min
ns min
ns max
ns min
ns min
ns max
2.25 V ≤ VDRIVE < 2.75 V
2.75 V ≤ VDRIVE < 3.3 V
3.3 V ≤ VDRIVE ≤ 3.6 V
SCLK low pulse width
SCLK high pulse width
SCLK to data valid hold time
t5
t6
t7
t8
tꢀ
2
CS
CS
rising edge to SDATAA, SDATAB, high impedance
rising edge to falling edge pulse width
2
t10
4.5
ꢀ.5
SCLK falling edge to SDATAA, SDATAB, high impedance
SCLK falling edge to SDATAA, SDATAB, high impedance
Latency
1 conversion latency
1 Temperature ranges are as follows: Y grade: −40°C to +125°C, B grade: −40°C to +85°C.
2 Specified with a load capacitance of 10 pF on SDATAA and SDATAB.
3 The time required for the output to cross 0.4 V or 2.4 V.
Rev. PrF | Page 5 of 20
AD7357
Preliminary Technical Data
ABSOLUTE MAXIMUM RATINGS
Table 4.
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Parameter
Rating
VDD to AGND, DGND, REFGND
−0.3 V to +3 V
−0.3 V to +5 V
−5 V to +3 V
VDRIVE to AGND, DGND, REFGND
VDD to VDRIVE
AGND to DGND to REFGND
Analog Input Voltages1 to AGND
−0.3 V to +0.3 V
−0.3 V to VDD + 0.3 V
−0.3 V to VDRIVE + 0.3V
−0.3 V to VDRIVE + 0.3 V
10 mA
Digital Input Voltages2 to DGND
Digital Output Voltages3 to DGND
Input Current to Any Pin Except Supplies4
Operating Temperature Range
Y Grade
ESD CAUTION
−40°C to +125°C
−40°C to +85°C
−65°C to +150°C
150°C
B Grade
Storage Temperature Range
Junction Temperature
TSSOP Package
θJA Thermal Impedance
θJC Thermal Impedance
Lead Temperature, Soldering
Reflow Temperature (10 to 30 sec)
ESD
143°C/W
45°C/W
255°C
2 kV
1 Analog input voltages are VINA+, VINA-, VINB+, VINB-, REFA, and REFB.
2
CS
Digital input voltages are
and SCLK.
3 Digital output voltages are SDATAA and SDATAB.
4 Transient currents of up to 100 mA do not cause SCR latch up.
Rev. PrF | Page 6 of 20
Preliminary Technical Data
AD7357
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
V
INA+
DRIVE
SCLK
SDATA
SDATA
DGND
AGND
CS
V
INA–
REF
A
A
B
AD7357
TOP VIEW
REFGND
AGND
(Not to Scale)
REF
B
INB–
INB+
V
V
V
DD
Figure 2.
Table 5. Pin Function Descriptions
Pin
No.
1, 2
3, 6
Mnemonic
VINA-, VINA+
REFA, REFB
Description
Analog Inputs of ADC A. These analog inputs form a fully differential pair.
Reference Decoupling Capacitor Pins. Decoupling capacitors are connected between these pins and the
REFGND pin to decouple the reference buffer for each respective ADC. It is recommended to decouple each
reference pin with a 10 µF capacitor. Provided the output is buffered, the on-chip reference can be taken from
these pins and applied externally to the rest of the system. The nominal internal reference voltage is 2.048 V and
appears at these pins. These pins can also be overdriven by an external reference. The input voltage range for
the external reference is 2.048 V +100 mV to VDD.
4
REFGND
AGND
Reference Ground. This is the ground reference point for the reference circuitry on the AD7357. Any external
reference signal should be referred to this REFGND voltage. Decoupling capacitors must be placed between this
pin and the REFA and REFB pins.
Analog Ground. This is the ground reference point for all analog circuitry on the AD7357. All analog input signals
and should be referred to this AGND voltage. The AGND and DGND voltages should ideally be at the same
potential and must not be more than 0.3 V apart, even on a transient basis.
5, 11
7, 8
ꢀ
VINB-, VINB+
VDD
Analog Inputs of ADC B. These analog inputs form a fully differential pair.
Power Supply Input. The VDD range for the AD7357 is 2.5 V 10ꢁ. The supply should be decoupled to AGND with
a 0.1 µF capacitor and a 10 µF tantalum capacitor.
10
12
CS
Chip Select. Active low logic input. This input provides the dual function of initiating conversions on the AD7357
and framing the serial data transfer.
Digital Ground. This is the ground reference point for all digital circuitry on the AD7357. This pin should connect
to the DGND plane of a system. The DGND and AGND voltages should ideally be at the same potential and must
not be more than 0.3 V apart, even on a transient basis.
DGND
13, 14 SDATAB, SDATAA Serial Data Outputs. The data output is supplied to each pin as a serial data stream. The bits are clocked out on
the falling edge of the SCLK input. 16 SCLK falling edges are required to access the 14 bits of data from the
AD7357. The data simultaneously appears on both data output pins from the simultaneous conversions of both
ADCs. The data stream consists of one leading zero followed by the 14 bits of conversion data followed by a
trailing zero. The data is provided MSB first. If CSis held low for 18 SCLK cycles rather than 16, then two further
trailing zeros appear after the 14 bits of data. If CSis held low for a further 18 SCLK cycles on either SDATAA or
SDATAB , the data from the other ADC follows on the SDATA pin. This allows data from a simultaneous
conversion on both ADCs to be gathered in serial format on either SDATAA or SDATAB.
15
SCLK
Serial Clock. Logic input. A serial clock input provides the SCLK for accessing the data from the AD7357. This
clock is also used as the clock source for the conversion process.
16
VDRIVE
Logic Power Supply Input. The voltage supplied at this pin determines at what voltage the interface operates.
This pin should be decoupled to DGND. The voltage at this pin may be different to that at VDD.
Rev. PrF | Page 7 of 20
AD7357
Preliminary Technical Data
TYPICAL PERFORMANCE CHARACTERISTICS
0
–20
–40
–60
–80
–100
–120
–140
0
250
500
4000
4000
750 1000 1250 1500 1750 2000
FREQUENCY (kHz)
Figure 3. Typical FFT
Figure 6. Histogram of Codes
1.0
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
0
8000
12,000
16,000
CODE
Figure 4. Typical DNL
Figure 7. SNR vs. Analog Input Frequency
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
0
8000
12,000
16,000
CODE
Figure 5. Typical INL
Figure 8. PSRR vs. Supply Ripple with No Supply Decoupling
Rev. PrF | Page 8 of 20
Preliminary Technical Data
AD7357
Figure 9. VREF vs. Reference Output Current Drive
Figure 10. Linearity Error vs. SCLK Frequency
Figure 11. Linearity Error vs. External VREF
Figure 12 Access Time vs. VDRIVE
Figure 13 Hold Time vs. VDRIVE
Rev. PrF | Page ꢀ of 20
AD7357
Preliminary Technical Data
TERMINOLOGY
Common-Mode Rejection Ratio (CMRR)
Integral Nonlinearity (INL)
CMRR is defined as the ratio of the power in the ADC output at
full-scale frequency, f, to the power of a 100 mV p-p sine wave
applied to the common-mode voltage of VIN+ and VIN− of
frequency, fS, as
INL is the maximum deviation from a straight line passing
through the endpoints of the ADC transfer function. The
endpoints of the transfer function are zero scale (1 LSB below
the first code transition) and full scale (1 LSB above the last
code transition).
CMRR (dB) = 10log (Pf/PfS)
Differential Nonlinearity (DNL)
where:
DNL is the difference between the measured and the ideal
1 LSB change between any two adjacent codes in the ADC.
Pf is the power at frequency, f, in the ADC output.
PfS is the power at frequency, fS, in the ADC output.
Negative Full-Scale Error
Track-and-Hold Acquisition Time
Negative full-scale error is the deviation of the first code
transition (00 … 000) to (00 … 001) from the ideal (that is,
−VREF + 0.5 LSB) after the midscale error has been adjusted out.
The track-and-hold amplifier returns to track mode at the end
of a conversion. The track-and-hold acquisition time is the time
required for the output of the track-and-hold amplifier to reach
its final value, within ±± LSB, after the end of conversion.
Negative Full-Scale Error Match
Negative full-scale error match is the difference in negative full-
Signal-to-(Noise + Distortion) Ratio (SINAD)
scale error between the two ADCs.
SINAD is the measured ratio of signal-to-(noise + distortion) at
the output of the ADC. The signal is the rms amplitude of the
fundamental. Noise is the sum of all nonfundamental signals up
to half the sampling frequency (fS/2), excluding dc. The ratio is
dependent on the number of quantization levels in the digitiza-
tion process; the more levels, the smaller the quantization noise.
Midscale Error
Midscale error is the deviation of the midscale code transition
(011 … 111) to (100 … 000) from the ideal (that is, 0 V).
Midscale Error Match
Midscale error match is the is the difference in midscale error
between the two ADCs.
The theoretical SINAD for an ideal N-bit converter with a sine
wave input is given by
Positive Full-Scale Error
Positive full-scale error is the deviation of the last code
transition (111 … 110) to (111 … 111) from the ideal (that is,
SINAD = (6.02 N + 1.76) dB
Thus, for a 12-bit converter, SINAD is 74 dB and for a 14-bit
converter, SINAD is 86 dB.
V
REF − 1.5 LSB) after the midscale error has been adjusted out.
Positive Full-Scale Error Match
Total Harmonic Distortion (THD)
Positive full-scale error match is the difference in positive full-
scale error between the two ADCs.
THD is the ratio of the rms sum of harmonics to the
fundamental. For the AD7357, it is defined as
ADC-to-ADC Isolation
2
2
2
2
2
V2 + V3 + V4 + V5 + V6
THD dB = −20 log
( )
ADC-to-ADC isolation is a measure of the level of crosstalk
between ADC A and ADC B. It is measured by applying a full-
scale 1 MHz sine wave signal to one of the two ADCs and
applying a full-scale signal of variable frequency to the other
ADC. The ADC-to-ADC isolation is defined as the ratio of the
power of the 1 MHz signal on the converted ADC to the power
of the noise signal on the other ADC that appears in the FFT.
The noise frequency on the unselected channel varies from
100 kHz to 2.5 MHz.
V1
where:
V1 is the rms amplitude of the fundamental.
V2, V3, V4, V5, and V6 are the rms amplitudes of the second
through the sixth harmonics.
Peak Harmonic or Spurious Noise
Peak harmonic or spurious noise is defined as the ratio of the
rms value of the next largest component in the ADC output
spectrum (up to fS/2 and excluding dc) to the rms value of the
fundamental. Normally, the value of this specification is
determined by the largest harmonic in the spectrum, but for
ADCs where the harmonics are buried in the noise floor, it is a
noise peak.
Power Supply Rejection Ratio (PSRR)
PSRR is defined as the ratio of the power in the ADC output at
full-scale frequency, f, to the power of a 100 mV p-p sine wave
applied to the ADC VDD supply of frequency fS. The frequency
of the input varies from 5 kHz to 25 MHz.
PSRR (dB) = 10 log(Pf/PfS)
where:
Pf is the power at frequency, f, in the ADC output.
PfS is the power at frequency, fS, in the ADC output.
Rev. PrF | Page 10 of 20
Preliminary Technical Data
AD7357
Intermodulation Distortion
sum of the individual distortion products to the rms amplitude
of the sum of the fundamentals expressed in decibels.
With inputs consisting of sine waves at two frequencies, fa and
fb, any active device with nonlinearities creates distortion
products at sum and difference frequencies of mfa ± nfb where
m, n = 0, 1, 2, 3, and so on. Intermodulation distortion terms
are those for which neither m nor n are equal to zero. For
example, the second-order terms include (fa + fb) and (fa − fb),
while the third-order terms include (2fa + fb), (2fa − fb), (fa +
2fb), and (fa − 2fb).
Thermal Hysteresis
Thermal hysteresis is defined as the absolute maximum change
of reference output voltage after the device is cycled through
temperature from either
T_HYS+ = 25°C to TMAX to 25°C
T_HYS– = 25°C to TMIN to 25°C
It is expressed in ppm using the following equation:
The AD7357 is tested using the CCIF standard where two input
frequencies near the top end of the input bandwidth are used.
In this case, the second-order terms are usually distanced in
frequency from the original sine waves, while the third-order
terms are usually at a frequency close to the input frequencies.
As a result, the second- and third-order terms are specified
separately. The calculation of the intermodulation distortion is
as per the THD specification, where it is the ratio of the rms
V
REF (25°C) −VREF (T _ HYS)
V
HYS (ppm) =
× 106
V
REF (25°C)
where:
REF(25°C) is VREF at 25°C
V
VREF(T_HYS) is the maximum change of VREF at T_HYS+ or
T_HYS–.
Rev. PrF | Page 11 of 20
AD7357
Preliminary Technical Data
THEORY OF OPERATION
DACs are used to add and subtract fixed amounts of charge
from the sampling capacitor arrays to bring the comparator
back into a balanced condition. When the comparator is
rebalanced, the conversion is complete. The control logic
generates the ADC output code. The output impedances of the
sources driving the VIN+ and VIN− pins must be matched,
otherwise the two inputs have different settling times, resulting
in errors.
CIRCUIT INFORMATION
The AD7357 is a high speed, dual, 14-bit, single-supply,
successive approximation analog-to-digital converter. The part
operates from a 2.5 V power supply and features throughput
rates up to 4.2 MSPS.
The AD7357 contains two on-chip differential track-and-hold
amplifiers, two successive approximation analog-to-digital
converters, and a serial interface with two separate data output
pins. The part is housed in a 16-lead TSSOP package, offering
the user considerable space-saving advantages over alternative
solutions.
CAPACITIVE
DAC
COMPARATOR
C
C
B
A
S
V
V
IN+
SW1
SW2
The serial clock input accesses data from the part, but also
provides the clock source for each successive approximation
ADC. The AD7357 has an on-chip 2.048 V reference. If an
external reference is desired the internal reference can be
overdriven with a reference of value ranging from (2.048 V +
100 mV) to VDD. If the internal reference is to be used elsewhere
in the system, then the reference output needs to be buffered
first. The differential analog input range for the AD7357 is VCM
± VREF/2.
CONTROL
LOGIC
SW3
S
A
B
IN–
V
REF
CAPACITIVE
DAC
Figure 15. ADC Conversion Phase
ANALOG INPUT STRUCTURE
Figure 16 shows the equivalent circuit of the analog input
structure of the AD7357. The four diodes provide ESD
protection for the analog inputs. Care must be taken to ensure
that the analog input signals never exceed the supply rails by
more than 300 mV. This causes these diodes to become
forward-biased and start conducting into the substrate. These
diodes can conduct up to 10 mA without causing irreversible
damage to the part.
The AD7357 features power-down options to allow power
saving between conversions. The power-down feature is
implemented via the standard serial interface, as described in
the Modes of Operation section.
CONVERTER OPERATION
The AD7357 has two successive approximation ADCs, each
based around two capacitive DACs. Figure 14 and Figure 15
show simplified schematics of one of these ADCs in acquisition
and conversion phase, respectively. The ADC is comprised of
control logic, a SAR, and two capacitive DACs. In Figure 14 (the
acquisition phase), SW3 is closed, SW1 and SW2 are in
Position A, the comparator is held in a balanced condition, and
the sampling capacitor arrays may acquire the differential signal
on the input.
The C1 capacitors in Figure 16 are typically 8 pF and can
primarily be attributed to pin capacitance. The R1 resistors are
lumped components made up of the on resistance of the
switches. The value of these resistors is typically about 30 Ω.
The C2 capacitors are the ADC’s sampling capacitors with a
capacitance of 32 pF typically.
V
DD
D
D
C2
R1
CAPACITIVE
DAC
V
IN+
C1
COMPARATOR
C
C
B
A
S
V
V
IN+
SW1
SW2
CONTROL
LOGIC
SW3
V
DD
S
A
B
IN–
D
D
C2
R1
V
IN–
V
REF
CAPACITIVE
DAC
C1
Figure 16.Equivalent Analog Input Circuit,
Conversion Phase—Switches Open, Track Phase—Switches Closed
Figure 14. ADC Acquisition Phase
When the ADC starts a conversion (Figure 15), SW3 opens and
SW1 and SW2 move to Position B, causing the comparator to
become unbalanced. Both inputs are disconnected once the
conversion begins. The control logic and charge redistribution
For ac applications, removing high frequency components from
the analog input signal is recommended by the use of an RC
low-pass filter on the analog input pins. In applications where
Rev. PrF | Page 12 of 20
Preliminary Technical Data
AD7357
harmonic distortion and signal-to-noise ratio are critical, the
analog input should be driven from a low impedance source.
Large source impedances significantly affect the ac performance
of the ADC and may necessitate the use of an input buffer
amplifier. The choice of the op amp is a function of the
particular application.
performance. Figure 19 defines the fully differential input of the
AD7357.
V
p-p
V
IN+
REF
AD7357*
COMMON-
MODE
VOLTAGE
V
p-p
V
REF
IN–
When no amplifier is used to drive the analog input, the source
impedance should be limited to low values. The maximum
source impedance depends on the amount of THD that can be
tolerated. The THD increases as the source impedance increases
and performance degrades. Figure 17 shows a graph of the THD
vs. the analog input signal frequency for various source
impedances.
*
ADDITIONAL PINS OMITTED FOR CLARITY.
Figure 19. Differential Input Definition
The amplitude of the differential signal is the difference
between the signals applied to the VIN+ and VIN− pins in each
differential pair (VIN+ − VIN−). VIN+ and VIN− should be
simultaneously driven by two signals each of amplitude VREF
that are 180° out of phase. This amplitude of the differential
signal is, therefore –VREF to +VREF peak-to-peak regardless of the
common mode (CM).
The common mode is the average of the two signals and is
therefore the voltage on which the two inputs are centered.
CM = (VIN+ + VIN−)/2
This results in the span of each input being CM ± VREF/2. This
voltage has to be set up externally. When setting up the CM,
ensure that that VIN+ and VIN− remain within GND/VDD. When a
conversion takes place, common mode is rejected resulting in a
virtually noise free signal of amplitude –VREF to +VREF
corresponding to the digital codes of 0 to 16383 for the
AD7357.
Figure 17. THD vs. Analog Input Frequency for Various Source Impedances
DRIVING DIFFERENTIAL INPUTS
Differential operation requires VIN+ and VIN− to be driven
simultaneously with two equal signals that are 180° out of
phase. Because not all applications have a signal preconditioned
for differential operation, there is often a need to perform a
single-ended-to-differential conversions.
Figure 18 shows a graph of the THD vs. the analog input
frequency while sampling at 4.2 MSPS. In this case, the source
impedance is 33 Ω.
Differential Amplifier
An ideal method of applying differential drive to the AD7357 is
to use a differential amplifier such as the AD8138. This part can
be used as a single-ended-to-differential amplifier or as a
differential-to-differential amplifier. The AD8138 also provides
common-mode level shifting. Figure 20 shows how the AD8138
can be used as a single-ended-to-differential amplifier. The
positive and negative outputs of the AD8138 are connected to
the respective inputs on the ADC via a pair of series resistors to
minimize the effects of switched capacitance on the front end of
the ADC. The architecture of the AD8138 results in outputs
that are very highly balanced over a wide frequency range
without requiring tightly matched external components.
Figure 18. THD vs. Analog Input Frequency
ANALOG INPUTS
Differential signals have some benefits over single-ended
signals, including noise immunity based on the devices
common-mode rejection and improvements in distortion
Rev. PrF | Page 13 of 20
AD7357
Preliminary Technical Data
into a Differential Signal
If the analog inputs source being used has zero impedance, all
four resistors (RG1, RG2, RF1, and RF2) should be the same. If the
source has a 50 Ω impedance and a 50 Ω termination, for
example, the value of RG2 should be increased by 25 Ω to
balance this parallel impedance on the input and thus ensure
that both the positive and negative analog inputs have the same
gain. The outputs of the amplifier are perfectly matched
balanced differential outputs of identical amplitude and are
exactly 180° out of phase.
2.048V
2 × V
REF
p-p
220Ω
1.024V
440Ω
V+
0V
V
REF
27Ω
V
IN+
GND
V–
220Ω
220Ω
2.048V
1.024V
0V
AD7357*
V+
27Ω
REF /REF
V
A
B
IN–
A
V–
C 1
10kΩ
F
10µF
2.048V
1.024V
20kΩ
R 1
F
0V
R
R
*
*
S
S
R
1
G
V
*ADDITIONAL PINS OMITTED FOR CLARITY.
IN+
V
OCM
Figure 22. Dual Op Amp Circuit to Convert a Single-Ended Bipolar Signal into
a Differential Unipolar Signal
+2.048V
GND
–2.048V
AD8138
AD7357
51Ω
R
2
G
V
REF /REF
A B
IN–
2.048V
1.024V
0V
R 2
F
ADC TRANSFER FUNCTION
C 2
F
The output coding for the AD7357 is straight binary. The
designed code transitions occur at successive LSB values (such
as, 1 LSB, 2 LSBs). The LSB size is (2 × VREF)/16384. The ideal
transfer characteristic of the AD7357 is shown in Figure 23.
10kΩ
10µF
10kΩ
*MOUNT AS CLOSE TO THE AD7357 AS POSSIBLE
AND ENSURE HIGH PRECISION R RESISTORS ARE USED.
S
R
R
– 33Ω; R 1 = R 1 = R 2 = 499Ω; C 1 = C 2 = 39pF;
G F F F F
S
G
2 = 523Ω.
111 ... 111
111 ... 110
111 ... 101
Figure 20. Using the AD8138 as a Single-Ended-to-Differential Amplifier
Op Amp Pair
An op amp pair can be used to directly couple a differential
signal to one of the analog input pairs of the AD7357. The
circuit configurations shown in Figure 21 and Figure 22 show
how an op amp pair can be used to convert a single-ended
signal into a differential signal for a bipolar and unipolar input
signal, respectively. The voltage applied to Point A sets up the
common-mode voltage. In both diagrams, it is connected in
some way to the reference. The AD8022 is a suitable dual op
amp that could be used in this configuration to provide
differential drive to the AD7357.
000 ... 010
000 ... 001
000 ... 000
–V
+ 1 LSB
+V
– 1 LSB
REF
REF
–V
+ 0.5 LSB
+V
– 1.5 LSB
REF
REF
ANALOG INPUT
Figure 23. AD7357 Deal Transfer Characteristic
2.048V
2 × V
REF
p-p
220Ω
V+
1.024V
0V
440Ω
V
REF
27Ω
V
IN+
GND
V–
220Ω
2.048V
1.024V
0V
AD7357*
220Ω
V+
27Ω
REF /REF
V
A
B
IN–
A
V–
10kΩ
10µF
*ADDITIONAL PINS OMITTED FOR CLARITY.
Figure 21. Dual Op Amp Circuit to Convert a Single-Ended Unipolar Signal
Rev. PrF | Page 14 of 20
Preliminary Technical Data
AD7357
MODES OF OPERATION
The mode of operation of the AD7357 is selected by controlling
Once a data transfer is complete and SDATAA and SDATAB have
returned to three-state, another conversion can be initiated after
CS
the logic state of the
signal during a conversion. There are
CS
the quiet time, tQUIET, has elapsed by bringing
low again
three possible modes of operation: normal mode, partial power-
down mode, and full power-down mode. After a conversion has
(assuming the required acquisition time has been allowed).
CS
been initiated, the point at which
which power-down mode, if any, the device enters. Similarly, if
CS
is pulled high determines
PARTIAL POWER-DOWN MODE
This mode is intended for use in applications where slower
throughput rates are required. Either the ADC is powered down
between each conversion, or a series of conversions may be
performed at a high throughput rate and the ADC is then
powered down for a relatively long duration between these
bursts of several conversions. When the AD7357 is in partial
power-down, all analog circuitry is powered down except for
the on-chip reference and reference buffers.
already in a power-down mode,
can control whether the
device returns to normal operation or remains in a power-down
mode. These modes of operation are designed to provide
flexible power management options. These options can be
chosen to optimize the power dissipation/throughput rate ratio
for the differing application requirements.
NORMAL MODE
Normal mode is intended for applications needing the fastest
throughput rates. The user does not have to worry about any
power-up times because the AD7357 remains fully powered at
all times. Figure 24 shows the general diagram of the operation
of the AD7357 in this mode.
To enter partial power-down mode, the conversion process
CS
must be interrupted by bringing
second falling edge of SCLK and before the 10th falling edge of
CS
high anywhere after the
SCLK, as shown in Figure 25. Once
has been brought high
in this window of SCLKs, the part enters partial power-down
mode, the conversion that was initiated by the falling edge of
is terminated, and SDATAA and SDATAB go back into three-
CS
CS
1
10
14
CS
state. If
is brought high before the second SCLK falling edge,
SCLK
the part remains in normal mode and does not power down.
D
A
B
OUT
CS
This avoids accidental power-down due to glitches on the
line.
LEADING ZEROS + CONVERSION RESULT
D
OUT
Figure 24. Normal Mode Operation
CS
CS
The conversion is initiated on the falling edge of , as
described in the Serial InterfaceError! Reference source not
found. section. To ensure that the part remains fully powered
1
2
10
14
SCLK
CS
up at all times,
must remain low until at least 10 SCLK
D
D
A
B
THREE-STATE
OUT
OUT
CS CS
falling edges have elapsed after the falling edge of . If
is
brought high any time after the 10th SCLK falling edge but
Figure 25. Entering Partial Power-Down Mode
before the 16th SCLK falling edge, the part remains powered up,
but the conversion is terminated and SDATAA and SDATAB go
back into three-state. 16 serial clock cycles are required to
complete the conversion and access the conversion result for the
AD7357. The SDATA lines do not return to three-state after 16
To exit this mode of operation and power up the AD7357 again,
CS
perform a dummy conversion. On the falling of , the device
CS
begins to power up, and continues to power up as long as
is
held low until after the falling edge of the 10th SCLK. The device
is fully powered up after approximately 200 ns has elapsed (or
one full conversion), and valid data results from the next
CS
SCLK cycles have elapsed, but instead do so when
is brought
is left low for another 2 SCLK cycles, two
CS
CS
high again. If
trailing zeros are clocked out after the data. If
CS
conversion, as shown in Figure 26. If
the second falling edge of SCLK, the AD7357 again goes into
partial power-down mode. This avoids accidental power-up due
is brought high before
is left low for a
further 16 SCLK cycles, the result for the other ADC on board
is also accessed on the same SDATA line as shown in Figure 31
(see the Serial Interface section).
CS
to glitches on the
power up on the falling edge of , it powers down again on the
CS
line. Although the device may begin to
CS
rising edge of . If the AD7357 is already in partial power-
Once 32 SCLK cycles have elapsed, the SDATA line returns to
three-state on the 32 SCLK falling edge. If
nd
CS
is brought high
CS
down mode and
is brought high between the second and
prior to this, the SDATA line returns to three-state at that point.
CS
10th falling edges of SCLK, the device enters full power-down
mode.
Thus,
may idle low after 32 SCLK cycles until it is brought
high again sometime prior to the next conversion if so desired,
because the bus still returns to three-state upon completion of
the dual result read.
Rev. PrF | Page 15 of 20
AD7357
Preliminary Technical Data
10th falling edge of SCLK. The device enters partial power-down
mode at this point.
FULL POWER-DOWN MODE
This mode is intended for use in applications where throughput
rates slower than those in the partial power-down mode are
required, as power-up from a full power-down takes
substantially longer than that from a partial power-down. This
mode is more suited to applications where a series of
To reach full power-down, the next conversion cycle must be
CS
interrupted in the same way, as shown in Figure 27. Once
has been brought high in this window of SCLKs, the part
completely powers down.
conversions performed at a relatively high throughput rate are
followed by a long period of inactivity and thus, power-down.
When the AD7357 is in full power-down, all analog circuitry is
powered down. Full power-down is entered in a similar way as
partial power-down, except that the timing sequence shown in
Figure 25 must be executed twice. The conversion process must
CS
Note that it is not necessary to complete the 16 SCLKs once
has been brought high to enter a power-down mode.
To exit full power-down mode and power-up the AD7357,
perform a dummy conversion, such as powering up from partial
CS
power-down. On the falling edge of , the device begins to
CS
power up, as long as
is held low until after the falling edge of
CS
be interrupted in a similar fashion by bringing
high
the 10th SCLK. The required power-up time must elapse before
a conversion can be initiated, as shown in Figure 28.
anywhere after the second falling edge of SCLK and before the
THE PART IS FULLY
POWERED UP; SEE
POWER-UP TIMES
SECTION.
THE PART BEGINS
TO POWER UP.
tPOWER-UP1
CS
1
10
14
1
14
SCLK
D
D
A
B
OUT
INVALID DATA
VALID DATA
OUT
Figure 26. Exiting Partial Power-Down Mode
THE PART ENTERS
PARTIAL POWER DOWN.
THE PART BEGINS
TO POWER UP.
THE PART ENTERS
FULL POWER DOWN.
CS
1
2
10
14
1
2
10
14
SCLK
D
A
THREE-STATE
THREE-STATE
OUT
INVALID DATA
INVALID DATA
D
B
OUT
Figure 27. Entering Full Power-Down Mode
THE PART IS FULLY POWERED UP,
SEE POWER-UP TIMES SECTION.
THE PART BEGINS
TO POWER UP.
tPOWER-UP2
CS
14
14
10
1
1
SCLK
D
D
A
B
OUT
INVALID DATA
VALID DATA
OUT
Figure 28. Exiting Full Power-Down Mode
Rev. PrF | Page 16 of 20
Preliminary Technical Data
AD7357
Alternatively, if the part is to be placed into full power-down
mode when the supplies are applied, three dummy cycles must
POWER-UP TIMES
The AD7357 has two power-down modes: partial power-down
and full power-down. There are described in detail in the
Partial Power-Down Mode and Full Power-Down Mode
sections. This section deals with the power-up time required
when coming out of either of these modes. It should be noted
that the power-up times apply with the recommended
decoupling capacitors in place on the REFA and REFB pins.
be initiated. The first dummy cycle must hold
low until after
CS
the 10th SCLK falling edge; the second and third dummy cycles
place the part into full power-down mode (see Figure 27 and
the Full Power-Down Mode section).
POWER vs. THROUGHPUT RATE
The power consumption of the AD7357 varies with the
throughput rate. When using very slow throughput rates
and as fast an SCLK frequency as possible, the various power-
down options can be used to make significant power savings.
However, the AD7357 quiescent current is low enough that
even without using the power-down options, there is a noticeable
variation in power consumption with sampling rate. This is true
whether a fixed SCLK value is used or if it is scaled with the
sampling rate. Figure 29 shows a plot of power vs. throughput rate
when operating in normal mode for a fixed maximum SCLK
frequency and an SCLK frequency that scales with the sampling
rate. The internal reference was used for Figure 29.
To power up from partial power-down mode, one dummy cycle
is required. The device is fully powered up after approximately
200 ns from the falling edge of
has elapsed. Once the partial
CS
power-up time has elapsed, the ADC is fully powered up and
the input signal is acquired properly. The quiet time, tQUIET, must
still be allowed from the point where the bus goes back into
three-state after the dummy conversion to the next falling edge
of
.
CS
To power up from full power-down, approximately 6 ms should
be allowed from the falling edge of , shown in Figure 28 as
CS
tPOWER-UP2
.
Note that during power-up from partial power-down mode, the
track-and-hold, which is in hold mode while the part is powered
down, returns to track mode after the first SCLK edge that the
part receives after the falling edge of
.
CS
When power supplies are first applied to the AD7357, the ADC
can power up in either of the power-down modes or in normal
mode. Because of this, it is best to allow a dummy cycle to
elapse to ensure that the part is fully powered up before
attempting a valid conversion. Likewise, if the part is to be kept
in partial power-down mode immediately after the supplies are
applied, then two dummy cycles must be initiated. The first
dummy cycle must hold
low until after the 10th SCLK falling
CS
edge; in the second cycle,
must be brought high between the
CS
second and 10th SCLK falling edges (see Figure 25).
Figure 29. Power vs. Throughput Rate
Rev. PrF | Page 17 of 20
AD7357
Preliminary Technical Data
SERIAL INTERFACE
goes back into three-state on the 32nd SCLK falling edge or the
Figure 30 shows the detailed timing diagram for serial
interfacing to the AD7357. The serial clock provides the
conversion clock and controls the transfer of information from
the AD7357 during conversion.
CS
rising edge of , whichever occurs first.
A minimum of 16 serial clock cycles are required to perform
the conversion process and to access data from one conversion
CS
on either data line of the AD7357.
going low provides the
CS
The
signal initiates the data transfer and conversion process.
CS
leading zero to be read in by the microcontroller or DSP. The
remaining data is then clocked out by subsequent SCLK falling
edges, beginning with a second leading zero. Thus, the first
falling clock edge on the serial clock has the leading zero
provided and also clocks out the second leading zero. The 14-bit
result then follows with the final bit in the data transfer valid on
the 16th falling edge, having being clocked out on the previous
(15th) falling edge. In applications with a slower SCLK, it may be
possible to read in data on each SCLK rising edge depending on
The falling edge of
puts the track and hold into hold mode at
which point the analog input is sampled and the bus is taken
out of three-state. The conversion is also initiated at this point
and requires a minimum of 16 SCLKs to complete. Once 15
SCLK falling edges have elapsed, the track and hold goes back
into track on the next SCLK rising edge, as shown in Figure 30
at Point B. On the rising edge of , the conversion will be
terminated and SDATAA and SDATAB go back into three-state.
CS
CS
If
is not brought high, but is instead held low for a further
CS
the SCLK frequency. The first rising edge of SCLK after the
16 SCLK cycles on SDATAA, the data from the conversion on
ADCB are output on SDATAA.
falling edge would have the second leading zero provided, and
the 15th rising SCLK edge would have DB0 provided.
CS
Likewise, if
is held low for a further 16 SCLK cycles on
SDATAA, the data from the conversion on ADC A is output on
SDATAB (see Figure 31). In this case, the SDATA line in use
tACQUISITION
CS
t9
tCONVERT
t2
t6
B
SCLK
3
4
5
1
2
15
16
t5
t8
t7
t3
t4
DB11
tQUIET
D
D
A
B
OUT
OUT
0
0
DB13
DB12
DB10
DB2
DB1
DB0
0
THREE-STATE
THREE-
STATE
2 LEADING ZEROS
Figure 30. Serial Interface Timing Diagram
CS
t6
t2
SCLK
3
4
5
1
2
15
16
17
18
31
32
t5
t3
t4
DB11
t7
DB13
DB12
DB0
DB12
DB1
DB0
B
0
0
0
0
0
DB13
D
A
A
A
A
A
B
B
B
OUT
THREE-
STATE
THREE-
STATE
2 LEADING
ZEROS
2 ZEROS
Figure 31. Reading Data from Both ADCs on One SDATA Line with 32 SCLKs
Rev. PrF | Page 18 of 20
Preliminary Technical Data
AD7357
APPLICATION HINTS
microstrip technique is the best method, but is not always
GROUNDING AND LAYOUT
possible with a double-sided board. In this technique, the
component side of the board is dedicated to ground planes,
while signals are placed on the solder side.
The analog and digital supplies to the AD7357 are independent
and separately pinned out to minimize coupling between the
analog and digital sections of the device. The printed circuit
board (PCB) that houses the AD7357 should be designed so
that the analog and digital sections are separated and confined
to certain areas of the board. This design facilitates the use of
ground planes that can be easily separated.
Good decoupling is important; all supplies should be decoupled
with 10 μF tantalum capacitors in parallel with 0.1 μF capacitors
to GND. To achieve the best results from these decoupling
components, they must be placed as close as possible to the
device, ideally right up against the device. The 0.1 μF capacitor
should have low effective series resistance (ESR) and effective
series inductance (ESI), such as the common ceramic types or
surface-mount types. These low ESR and ESI capacitors provide
a low impedance path to ground at high frequencies to handle
transient currents due to logic switching.
To provide optimum shielding for ground planes, a minimum
etch technique is generally best. The two AGND pins of the
AD7357 should be sunk in the AGND plane. Digital and analog
ground plans should be joined in only one place. If the AD7357
is in a system where multiple devices require an AGND and
DGND connection, the connection should still be made at one
point only. A star ground point that should be established as
close as possible to the ground pins on the AD7357.
EVALUATING THE AD7357 PERFORMANCE
The recommended layout for the AD7357 is outlined in the
evaluation board documentation. The evaluation board package
includes a fully assembled and tested evaluation board, docu-
mentation, and software for controlling the board from the PC
via the converter evaluation and development board (CED).
The CED can be used in conjunction with the AD7357
evaluation board (as well as many other evaluation boards
ending in the ED designator from Analog Devices, Inc.) to
demonstrate/evaluate the ac and dc performance of the
AD7357.
Avoid running digital lines under the device because this
couples noise onto the die. The analog ground planes should be
allowed to run under the AD7357 to avoid noise coupling. The
power supply lines to the AD7357 should use as large a trace as
possible to provide low impedance paths and reduce the effects
of glitches on the power supply line.
To avoid radiating noise to other sections of the board, fast
switching signals such as clocks, should be shielded with digital
ground, and clock signals should never run near the analog
inputs. Avoid crossover of digital and analog signals. To reduce
the effects of feedthrough within the board, traces on opposite
sides of the board should run at right angles to each other. A
The software allows the user to perform ac (fast Fourier transform)
and dc (linearity) tests on the AD7357. The software and docu-
mentation are on a CD shipped with the evaluation board.
Rev. PrF | Page 1ꢀ of 20
AD7357
Preliminary Technical Data
OUTLINE DIMENSIONS
5.10
5.00
4.90
16
9
8
4.50
4.40
4.30
6.40
BSC
1
PIN 1
1.20
MAX
0.15
0.05
0.20
0.09
0.75
0.60
0.45
8°
0°
0.30
0.19
0.65
BSC
SEATING
PLANE
COPLANARITY
0.10
COMPLIANT TO JEDEC STANDARDS MO-153-AB
Figure 32. 16-Lead Thin Shrink Small Outline Package [TSSOP]
(RU-16)
Dimensions shown in millimeters
ORDERING GUIDE
Model
Temperature Range
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
Package Description
16-Lead TSSOP
16-Lead TSSOP
16-Lead TSSOP
16-Lead TSSOP
16-Lead TSSOP
16-Lead TSSOP
Package Option
RU-16
RU-16
RU-16
RU-16
AD7357BRUZ1
AD7357BRUZ-500RL71
AD7357BRUZ-RL1
AD7357YRUZ1
AD7357YRUZ-500RL71
AD7357YRUZ-RL1
RU-16
RU-16
1 Z = RoHS Compliant Part.
©2008 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
PR07757-0-11/08(PrF)
Rev. PrF | Page 20 of 20
相关型号：
©2020 ICPDF网 联系我们和版权申明