MAX5441_08 [MAXIM]
3V/5V, Serial-Input, Voltage-Output, 16-Bit DACs; 3V / 5V ,串行输入,电压输出, 16位DAC型号: | MAX5441_08 |
厂家: | MAXIM INTEGRATED PRODUCTS |
描述: | 3V/5V, Serial-Input, Voltage-Output, 16-Bit DACs |
文件: | 总12页 (文件大小:219K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
19-1846; Rev 2; 10/07
+3V/+5V, Serial-Input,
Voltage-Output, 16-Bit DACs
1–MAX54
General Description
Features
♦ Ultra-Small 3mm x 5mm 8-Pin µMAX Package
The MAX5441–MAX5444 are serial-input, voltage-out-
put, 16-bit digital-to-analog converters (DACs) in tiny
♦ Low 120µA Supply Current
♦ Fast 1µs Settling Time
®
µMAX packages, 50% smaller than comparable DACs
in 8-pin SOs. They operate from low +3V (MAX5443/
MAX5444) or +5V (MAX5441/MAX5442) single sup-
plies. They provide 16-bit performance ( 2ꢀSꢁ ꢂIꢀ and
1ꢀSꢁ DIꢀ) over temperature without any adꢃustments.
Unbuffered DAC outputs result in a low supply current
of 120µA and a low offset error of 2ꢀSꢁ.
♦ 25MHz SPI/QSPI/MICROWIRE-Compatible Serial
Interface
♦ V
Range Extends to V
DD
REF
♦ +5V (MAX5441/MAX5442) or +3V
(MAX5443/MAX5444) Single-Supply Operation
The DAC output ranges from 0 to V
. For bipolar
REF
♦ Full 16-Bit Performance Without Adjustments
operation, matched scaling resistors are provided in
the MAX5442/MAX5444 for use with an external preci-
sion op amp (such as the MAX400), generating a
♦ Unbuffered Voltage Output Directly Drives
60kΩ Loads
V
REF
output swing.
♦ Power-On Reset Circuit Clears DAC Output to
Code 0 (MAX5441/MAX5443) or Code 32768
(MAX5442/MAX5444)
A 16-bit serial word is used to load data into the DAC
latch. The 25MHz, 3-wire serial interface is compatible
with SPꢂ™/QSPꢂ™/MꢂCROWꢂRE™, and can interface
directly with optocouplers for applications requiring isola-
tion. A power-on reset circuit clears the DAC output to
code 0 (MAX5441/MAX5443) or code 32768 (MAX5442
/MAX5444) when power is initially applied.
♦ Schmitt-Trigger Inputs for Direct Optocoupler
Interface
♦ Asynchronous CLR
Pin Configurations
A logic low on CLR asynchronously clears the DAC out-
put to code 0 (MAX5441/MAX5443) or code 32768
(MAX5442/MAX5444) independent of the serial interface.
TOP VIEW
The MAX5441/MAX5443 are available in 8-pin µMAX
packages. The MAX5442/MAX5444 are available in 10-
pin µMAX packages.
GND
REF
CS
1
2
3
4
5
10
9
GND
1
2
3
4
8
7
6
5
REF
CS
V
DD
V
DD
MAX5441
MAX5443
MAX5442
MAX5444
SCLK
DIN
8
RFB
INV
Applications
High-Resolution Offset and Gain Adꢃustment
ꢂndustrial Process Control
OUT
CLR
SCLK
DIN
7
CLR
OUT
6
µMAX-8
µMAX-10
Automated Test Equipment
Data-Acquisition Systems
Functional Diagrams appear at end of data sheet.
Ordering Information
PART
MAX5441ACUA
MAX5441AEUA
MAX5441ꢁCUA
MAX5441ꢁEUA
MAX5442ACUꢁ
MAX5442AEUꢁ
MAX5442ꢁCUꢁ
MAX5442ꢁEUꢁ
TEMP RANGE
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
8 µMAX
INL (LSB)
SUPPLY (V)
2
2
4
4
2
2
4
4
5
5
5
5
5
5
5
5
8 µMAX
8 µMAX
8 µMAX
10 µMAX
10 µMAX
10 µMAX
10 µMAX
µMAX is a registered trademark of Maxim ꢂntegrated Products, ꢂnc.
SPꢂ and QSPꢂ are trademarks of Motorola, ꢂnc.
Ordering Information continued at end of data sheet.
MꢂCROWꢂRE is a trademark of Iational Semiconductor Corp.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
+3V/+5V, Serial-Input,
Voltage-Output, 16-Bit DACs
ABSOLUTE MAXIMUM RATINGS
V
to GID..............................................................-0.3V to +6V
Continuous Power Dissipation (T = +70°C)
A
DD
CS, SCꢀK, DꢂI, CLR to GID ...................................-0.3V to +6V
REF to GID................................................-0.3V to (V + 0.3V)
OUT, ꢂIV to GID .....................................................-0.3V to V
8-Pin µMAX (derate 4.5mW/°C above +70°C)...............362mW
10-Pin µMAX (derate 5.6mW/°C above +70°C) ..............444mW
Operating Temperature Ranges
DD
DD
RFꢁ to ꢂIV...................................................................-6V to +6V
RFꢁ to GID.................................................................-6V to +6V
Maximum Current ꢂnto Any Pin ...........................................50mA
MAX544 _ _CU_ ...................................................0°C to +70°C
MAX544 _ _EU_.................................................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Maximum Die Temperature..............................................+150°C
ꢀead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
DD
(V
= +3V (MAX5443/MAX5444) or +5V (MAX5441/MAX5442), V
= +2.5V, C = 10pF, GID = 0, R = ∞, T = T
to T
,
MAX
REF
ꢀ
ꢀ
A
MꢂI
unless otherwise noted. Typical values are at T = +25°C.)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
STATIC PERFORMANCE—ANALOG SECTION
1–MAX54
Resolution
I
16
ꢁits
Differential Ionlinearity
DIꢀ
Guaranteed monotonic
0.5
0.5
0.5
1
2
4
2
ꢀSꢁ
MAX544_A
MAX544_ꢁ
ꢂntegral Ionlinearity
ꢂIꢀ
ꢀSꢁ
Zero-Code Offset Error
Zero-Code Tempco
Gain Error (Iote 1)
ZSE
ꢀSꢁ
ppm/°C
ꢀSꢁ
ZS
0.05
TC
10
Gain-Error Tempco
DAC Output Resistance
0.1
6.2
1
ppm/°C
kΩ
R
(Iote 2)
OUT
R
/R
Fꢁ ꢂIV
ꢁipolar Resistor Matching
%
Ratio error
0.015
20
ꢁipolar Zero Offset Error
ꢁipolar Zero Tempco
ꢀSꢁ
ꢁZS
0.5
ppm/°C
TC
+2.7V ≤ V
+4.5V ≤ V
≤ +3.3V (MAX5443/MAX5444)
≤ +5.5V (MAX5441/MAX5442)
1
1
DD
Power-Supply Reꢃection
PSR
ꢀSꢁ
DD
REFERENCE INPUT
Reference ꢂnput Range
V
R
(Iote 3)
2.0
10
6
V
V
REF
DD
Unipolar mode
ꢁipolar mode
Reference ꢂnput Resistance
(Iote 4)
kΩ
REF
DYNAMIC PERFORMANCE—ANALOG SECTION
Voltage-Output Slew Rate
Output Settling Time
DAC Glitch ꢂmpulse
SR
(Iote 5)
To 1/2ꢀSꢁ of FS
15
1
V/µs
µs
Maꢃor-carry transition
7
nV-s
Code = 0000 hex; CS = V
;
DD
Digital Feedthrough
0.2
nV-s
SCꢀK, DꢂI = 0 to V
levels
DD
2
_______________________________________________________________________________________
+3V/+5V, Serial-Input,
Voltage-Output, 16-Bit DACs
1–MAX54
ELECTRICAL CHARACTERISTICS (continued)
(V
= +3V (MAX5443/MAX5444) or +5V (MAX5441/MAX5442), V
= +2.5V, C = 10pF, GID = 0, R = ∞, T = T
to T
,
MAX
DD
REF
ꢀ
ꢀ
A
MꢂI
unless otherwise noted. Typical values are at T = +25°C.)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DYNAMIC PERFORMANCE—REFERENCE SECTION
Reference -3dꢁ ꢁandwidth
Reference Feedthrough
Signal-to-Ioise Ratio
ꢁW
Code = FFFF hex
1
1
MHz
Code = 0000 hex, V
= 1V
at 100kHz
mV
P-P
REF
P-P
SIR
92
70
170
dꢁ
Code = 0000 hex
Code = FFFF hex
Reference ꢂnput Capacitance
C
ꢂIREF
pF
STATIC PERFORMANCE—DIGITAL INPUTS
ꢂnput High Voltage
ꢂnput ꢀow Voltage
ꢂnput Current
V
2.4
V
V
ꢂH
V
0.8
1
ꢂꢀ
ꢂ
ꢂI
µA
pF
V
ꢂnput Capacitance
Hysteresis Voltage
POWER SUPPLY
C
(Iote 6)
3
10
ꢂI
V
0.15
H
MAX5443/MAX5444
MAX5441/MAX5442
2.7
4.5
3.6
5.5
Positive Supply Range (Iote 7)
Positive Supply Current
Power Dissipation
V
V
DD
ꢂ
All digital inputs at V
or GID
0.12
0.36
0.60
0.20
mA
mW
DD
DD
MAX5443/MAX5444
MAX5441/MAX5442
All digital inputs at
PD
V
DD
or GID
TIMING CHARACTERISTICS
(V
= +2.7V to +3.3V (MA5443/MAX5444) , V
= +4.5V to +5.5V (MAX5441/MAX5442), V
= +2.5V, GID = 0, CMOS inputs,
DD
DD
REF
T
A
= T
to T
, unless otherwise noted. Typical values are at T = +25°C.) (Figure 1)
MAX A
MꢂI
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MHz
ns
SCꢀK Frequency
f
25
CꢀK
SCꢀK Pulse Width High
SCꢀK Pulse Width ꢀow
CS ꢀow to SCꢀK High Setup
CS High to SCꢀK High Setup
SCꢀK High to CS ꢀow Hold
SCꢀK High to CS High Hold
DꢂI to SCꢀK High Setup
DꢂI to SCꢀK High Hold
CLR Pulse Width ꢀow
t
20
20
15
15
35
20
15
0
CH
t
Cꢀ
ns
t
t
t
ns
CSS0
CSS1
ns
(Iote 6)
ns
CSH0
CSH1
t
ns
t
ns
DS
t
ns
DH
t
20
ns
CꢀW
V
High to CS ꢀow
DD
20
µs
(power-up delay)
Note 1: Gain error tested at V
= +2.0V, +2.5V, and +3.0V (MAX5443/MAX5444) or V
= +2.0V, +2.5V, +3.0V, and +5.5V
REF
REF
(MAX5441/ MAX5442).
Note 2: R tolerance is typically 20%.
OUT
Note 3: Min/max range guaranteed by gain-error test. Operation outside min/max limits will result in degraded performance.
Note 4: Reference input resistance is code-dependent, minimum at 8555hex in unipolar mode, 4555hex in bipolar mode.
Note 5: Slew-rate value is measured from 10% to 90%.
Note 6: Guaranteed by design. Iot production tested.
Note 7: Guaranteed by power-supply reꢃection test and Timing Characteristics.
_______________________________________________________________________________________
3
+3V/+5V, Serial-Input,
Voltage-Output, 16-Bit DACs
__________________________________________Typical Operating Characteristics
(V
= +3V (MAX5443/MAX5444) or +5V (MAX5441/MAX5442), V
= +2.5V, GID = 0, R = ∞, T = T
to T
, unless other-
MAX
DD
REF
ꢀ
A
MꢂI
wise noted. Typical values are at T = +25°C.)
A
SUPPLY CURRENT
vs. REFERENCE VOLTAGE
SUPPLY CURRENT
vs. REFERENCE VOLTAGE
SUPPLY CURRENT vs. TEMPERATURE
0.12
0.11
0.10
0.09
0.08
0.07
0.06
0.05
0.12
0.11
0.150
0.125
0.100
0.075
0.050
0.025
0
V
DD
= +5V
0.10
V
DD
= +3V
0.09
0.08
0.07
0.06
0.05
V
DD
= +5V
V
= +3V
DD
0
-40
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
REFERENCE VOLTAGE (V)
0
0.5
1.0
1.5
2.0
2.5
3.0
-40
-40
-40
-15
10
35
60
85
85
85
1–MAX54
REFERENCE VOLTAGE (V)
TEMPERATURE (°C)
DIFFERENTIAL NONLINEARITY
vs. TEMPERATURE
ZERO-CODE OFFSET ERROR
vs. TEMPERATURE
INTEGRAL NONLINEARITY
vs. TEMPERATURE
0.8
0.6
0.4
0.2
0
0.2
0.1
0.4
0.3
0.2
0.1
0
+INL
+DNL
0
-0.1
-0.2
-0.3
-0.4
-DNL
-INL
-0.1
-0.2
-0.2
-0.4
-15
10
TEMPERATURE (°C)
35
60
85
-40
-15
10
35
60
85
-15
10
35
60
TEMPERATURE (°C)
TEMPERATURE (°C)
GAIN ERROR
vs. TEMPERATURE
DIFFERENTIAL NONLINEARITY
INTEGRAL NONLINEARITY vs. CODE
0.125
0.100
0.075
0.050
0.025
0
0.25
0.20
0.15
0.10
0.05
0
0
-0.05
-0.10
-0.15
-0.20
-0.25
-0.30
-0.025
-0.050
-0.075
-0.05
-0.10
-0.15
-0.100
-0.125
-0.20
-0.25
-15
10
35
60
35k
35k
0
5k 15k 25k
45k 55k 66k
5k 15k 25k
45k 55k 66k
TEMPERATURE (°C)
CODE
CODE
4
_______________________________________________________________________________________
+3V/+5V, Serial-Input,
Voltage-Output, 16-Bit DACs
1–MAX54
Typical Operating Characteristics (continued)
(V
= +3V (MAX5443/MAX5444) or +5V (MAX5441/MAX5442), V
= +2.5V, GID = 0, R = ∞, T = T
to T
, unless other-
MAX
DD
REF
ꢀ
A
MꢂI
wise noted. Typical values are at T = +25°C.)
A
FULL-SCALE STEP RESPONSE
(FALLING)
FULL-SCALE STEP RESPONSE
(RISING)
REFERENCE CURRENT
vs. DIGITAL INPUT CODE
140
MAX5441/44 toc11
120
100
80
60
40
20
0
CS
2V/div
CS
2V/div
A
OUT
A
OUT
1V/div
1V/div
C = 20pF
L
C = 20pF
L
400ns/div
0
10000 20000 30000 40000 50000 60000 70000
CODE
400ns/div
MAJOR-CARRY GLITCH
MAJOR-CARRY GLITCH
(FALLING)
(RISING)
CS
1V/div
CS
1V/div
A
OUT
20mV/div
A
OUT
20mV/div
C = 20pF
L
C = 20pF
L
200ns/div
200ns/div
INTEGRAL NONLINEARITY
vs. REFERENCE VOLTAGE
UNIPOLAR POWER-ON GLITCH
(REF = V
DIGITAL FEEDTHROUGH
)
DD
0.70
0.65
0.60
0.55
0.50
0.45
0.40
V
DD
2V/div
D
IN
2V/div
V
OUT
10mV/div
A
OUT
10mV/div
C = 112pF
L
50ns/div
2.0
2.5
3.0
3.5
4.0
4.5
5.0
50ms/div
REFERENCE VOLTAGE (V)
_______________________________________________________________________________________
5
+3V/+5V, Serial-Input,
Voltage-Output, 16-Bit DACs
Pin Description
PIN
NAME
FUNCTION
MAX5441
MAX5443
MAX5442
MAX5444
1
2
3
4
1
2
3
4
REF
CS
Voltage Reference ꢂnput
Chip-Select ꢂnput
SCꢀK
DꢂI
Serial Clock ꢂnput. Duty cycle must be between 40% and 60%.
Serial Data ꢂnput
Clear ꢂnput. ꢀogic low asynchronously clears the DAC to code 0 (MAX5441/MAX5443)
or code 32768 (MAX5442/MAX5444).
5
6
5
6
7
CLR
OUT
ꢂIV
DAC Output Voltage
Junction of ꢂnternal Scaling Resistors. Connect to external op amp’s inverting input in
bipolar mode.
—
—
7
8
9
RFꢁ
Feedback Resistor. Connect to external op amp’s output in bipolar mode.
Supply Voltage. Use +3V for MAX5443/MAX5444 and +5V for MAX5441/MAX5442.
Ground
V
DD
1–MAX54
8
10
GID
t
CSH1
CS
t
CSHO
t
CSS1
t
t
t
CL
CSSO
CH
SCLK
DIN
t
DH
t
DS
D15
D14
D0
Figure 1. Timing Diagram
6
_______________________________________________________________________________________
+3V/+5V, Serial-Input,
Voltage-Output, 16-Bit DACs
1–MAX54
+2.5V
MAX6166
+3V/+5V
1µF
0.1µF
0.1µF
V
REF
DD
MC68XXXX
UNIPOLAR
OUT
CS
PCS0
MOSI
MAX495
EXTERNAL OP AMP
MAX5441
MAX5442
MAX5443
MAX5444
OUT
DIN
SCLK
CLR
SCLK
IC1
(GND)
GND
Figure 2a. Typical Operating Circuit—Unipolar Output
+2.5V
MAX6166
+3V/+5V
1µF
0.1µF
0.1µF
+5V
RFB
MC68XXXX
V
DD
R
INV
PCS0
MOSI
SCLK
IC1
CS
R
INV
FB
BIPOLAR
OUT
EXTERNAL OP AMP
MAX400
DIN
OUT
SCLK
CLR
MAX5442
MAX5444
-5V
(GND)
GND
Figure 2b. Typical Operating Circuit—ꢁipolar Output
The MAX5441–MAX5444 are composed of two
matched DAC sections, with a 12-bit inverted R-2R
DAC forming the 12 ꢀSꢁs and the four MSꢁs derived
from 15 identically matched resistors. This architecture
allows the lowest glitch energy to be transferred to the
DAC output on maꢃor-carry transitions. ꢂt also lowers the
DAC output impedance by a factor of eight compared
Detailed Description
The MAX5441–MAX5444 voltage-output, 16-bit digital-
to-analog converters (DACs) offer full 16-bit perfor-
mance with less than 2ꢀSꢁ integral linearity error and
less than 1ꢀSꢁ differential linearity error, thus ensuring
monotonic performance. Serial data transfer minimizes
the number of package pins required.
_______________________________________________________________________________________
7
+3V/+5V, Serial-Input,
Voltage-Output, 16-Bit DACs
to a standard R-2R ladder, allowing unbuffered opera-
tion in medium-load applications.
MAX5442/MAX5444 to code 32768 when V
is first
DD
applied. This ensures that unwanted DAC output volt-
ages will not occur immediately following a system
power-up, such as after a loss of power.
The MAX5442/MAX5444 provide matched bipolar offset
resistors, which connect to an external op amp for bipo-
lar output swings (Figure 2b).
Applications Information
Digital Interface
The MAX5441–MAX5444 digital interface is a standard
3-wire connection compatible with SPꢂ/QSPꢂ/
MꢂCROWꢂRE interfaces. The chip-select input (CS)
frames the serial data loading at the data-input pin
(DꢂI). ꢂmmediately following CS’s high-to-low transition,
the data is shifted synchronously and latched into the
input register on the rising edge of the serial clock input
(SCꢀK). After 16 data bits have been loaded into the
serial input register, it transfers its contents to the DAC
latch on CS’s low-to-high transition (Figure 3). Iote that
if CS is not kept low during the entire 16 SCꢀK cycles,
data will be corrupted. ꢂn this case, reload the DAC
latch with a new 16-bit word.
Reference and Ground Inputs
The MAX5441–MAX5444 operate with external voltage
references from 2V to V , and maintain 16-bit perfor-
DD
mance if certain guidelines are followed when selecting
and applying the reference. ꢂdeally, the reference’s
temperature coefficient should be less than
0.1ppm/°C to maintain 16-bit accuracy to within 1ꢀSꢁ
over the -40°C to +85°C extended temperature range.
Since this converter is designed as an inverted R-2R volt-
age-mode DAC, the input resistance seen by the voltage
reference is code-dependent. ꢂn unipolar mode, the
worst-case input-resistance variation is from 11.5kΩ (at
code 8555hex) to 200kΩ (at code 0000hex). The maxi-
mum change in load current for a 2.5V reference is 2.5V /
11.5k Ω = 217µA; therefore, the required load regulation
is 7ppm/mA for a maximum error of 0.1ꢀSꢁ. This implies
a reference output impedance of less than 18mΩ. ꢂn
addition, the impedance of the signal path from the volt-
age reference to the reference input must be kept low
because it contributes directly to the load-regulation
error.
1–MAX54
Clearing the DAC
A 20ns (min) logic-low pulse on CLR asynchronously
clears the DAC buffer to code 0 in the MAX5441/
MAX5443 and to code 32768 in the MAX5442/ MAX5444.
External Reference
The MAX5441–MAX5444 operate with external voltage
references from 2V to V . The reference voltage
DD
The requirement for a low-impedance voltage reference
is met with capacitor bypassing at the reference inputs
and ground. A 0.1µF ceramic capacitor with short leads
between REF and GID provides high-frequency
bypassing. A surface-mount ceramic chip capacitor is
preferred because it has the lowest inductance. An
determines the DAC’s full-scale output voltage.
Power-On Reset
The power-on reset circuit sets the output of the
MAX5441/MAX5443 to code 0 and the output of the
CS
DAC
UPDATED
SCLK
SUB-BITS
DIN
D15 D14 D13 D12 D11 D10 D9 D8
MSB
D7 D6 D5 D4 D3 D2 D1 D0
LSB
Figure 3. MAX5441–MAX5444 3-Wire ꢂnterface Timing Diagram
8
_______________________________________________________________________________________
+3V/+5V, Serial-Input,
Voltage-Output, 16-Bit DACs
1–MAX54
additional 1µF between REF and GID provides low-fre-
add less than 1/2ꢀSꢁ of zero-scale error. The external
amplifier’s input resistance forms a resistive divider with
the DAC output resistance, which results in a gain error.
To contribute less than 1/2ꢀSꢁ of gain error, the input
resistance typically must be greater than:
quency bypassing. A low-ESR tantalum, film, or organic
semiconductor capacitor works well. ꢀeaded capaci-
tors are acceptable because impedance is not as criti-
cal at lower frequencies. The circuit can benefit from
even larger bypassing capacitors, depending on the
stability of the external reference with capacitive loading.
17
6.25kΩ × 2 = 819MΩ
Unbuffered Operation
Unbuffered operation reduces power consumption as
well as offset error contributed by the external output
buffer. The R-2R DAC output is available directly at
The settling time is affected by the buffer input capaci-
tance, the DAC’s output capacitance, and PC board
capacitance. The typical DAC output voltage settling
time is 1µs for a full-scale step. Settling time can be sig-
nificantly less for smaller step changes. Assuming a
single time-constant exponential settling response, a
full-scale step takes 12 time constants to settle to within
1/2ꢀSꢁ of the final output voltage. The time constant is
equal to the DAC output resistance multiplied by the
total output capacitance. The DAC output capacitance
is typically 10pF. Any additional output capacitance will
increase the settling time.
OUT, allowing 16-bit performance from +V
to GID
REF
without degradation at zero-scale. The DAC’s output
impedance is also low enough to drive medium loads
(R > 60kΩ) without degradation of ꢂIꢀ or DIꢀ; only
ꢀ
the gain error is increased by externally loading the
DAC output.
External Output Buffer Amplifier
The requirements on the external output buffer amplifier
change whether the DAC is used in the unipolar or bipo-
lar mode of operation. ꢂn unipolar mode, the output
amplifier is used in a voltage-follower connection. ꢂn
bipolar mode (MAX5442/MAX5444 only), the amplifier
operates with the internal scaling resistors (Figure 2b). ꢂn
each mode, the DAC’s output resistance is constant and
is independent of input code; however, the output ampli-
fier’s input impedance should still be as high as possible
to minimize gain errors. The DAC’s output capacitance is
also independent of input code, thus simplifying stability
requirements on the external amplifier.
The external buffer amplifier’s gain-bandwidth product
is important because it increases the settling time by
adding another time constant to the output response.
The effective time constant of two cascaded systems,
each with a single time-constant response, is approxi-
mately the root square sum of the two time constants.
The DAC output’s time constant is 1µs / 12 = 83ns,
ignoring the effect of additional capacitance. ꢂf the time
constant of an external amplifier with 1MHz bandwidth
is 1 / 2π (1MHz) = 159ns, then the effective time con-
stant of the combined system is:
ꢂn bipolar mode, a precision amplifier operating with
dual power supplies (such as the MAX400) provides
2
2
⎡
⎣
⎤
⎦
83ns + 159ns
=180ns
(
)
(
)
⎢
⎥
the
V
output range. ꢂn single-supply applications,
REF
precision amplifiers with input common-mode ranges
including GID are available; however, their output
swings do not normally include the negative rail (GID)
without significant degradation of performance. A sin-
gle-supply op amp, such as the MAX495, is suitable if
the application does not use codes near zero.
This suggests that the settling time to within 1/2ꢀSꢁ of
the final output voltage, including the external buffer
✕
amplifier, will be approximately 12 180ns = 2.15µs.
Digital Inputs and Interface Logic
The digital interface for the 16-bit DAC is based on a
3-wire standard that is compatible with SPꢂ, QSPꢂ, and
MꢂCROWꢂRE interfaces. The three digital inputs (CS,
DꢂI, and SCꢀK) load the digital input data serially into
the DAC.
Since the ꢀSꢁs for a 16-bit DAC are extremely small
(38.15µV for V
= 2.5V), pay close attention to the
REF
external amplifier’s input specification. The input offset
voltage can degrade the zero-scale error and might
require an output offset trim to maintain full accuracy if
the offset voltage is greater than 1/2ꢀSꢁ. Similarly, the
input bias current multiplied by the DAC output resis-
tance (typically 6.25kΩ) contributes to the zero-scale
error. Temperature effects also must be taken into con-
sideration. Over the -40°C to +85°C extended tempera-
ture range, the offset voltage temperature coefficient
(referenced to +25°C) must be less than 0.24µV/°C to
A 20ns (min) logic-low pulse on CLR clears the data in
the DAC buffer.
All of the digital inputs include Schmitt-trigger buffers to
accept slow-transition interfaces. This means that opto-
couplers can interface directly to the MAX5441–
MAX5444 without additional external logic. The digital
inputs are compatible with TTꢀ/CMOS-logic levels.
_______________________________________________________________________________________
9
+3V/+5V, Serial-Input,
Voltage-Output, 16-Bit DACs
Unipolar Configuration
Table 1. Unipolar Code Table
Figure 2a shows the MAX5441–MAX5444 configured for
unipolar operation with an external op amp. The op amp
is set for unity gain, and Table 1 lists the codes for this
circuit. The bipolar MAX5442/MAX5444 can also be
used in unipolar configuration by connecting RFꢁ and
ꢂIV to REF. This allows the DAC to power-up to mid-
scale.
DAC LATCH CONTENTS
MSB LSB
ANALOG OUTPUT, V
OUT
✕
V
V
(65,535 / 65,536)
1111 1111 1111 1111
1000 0000 0000 0000
0000 0000 0000 0001
0000 0000 0000 0000
REF
1/
V
REF
2
✕
✕
(32,768 / 65,536) =
(1 / 65,536)
REF
V
REF
0
Bipolar Configuration
Figure 2b shows the MAX5442/MAX5444 configured for
bipolar operation with an external op amp. The op amp
Table 2. Bipolar Code Table
is set for unity gain with an offset of -1/2V
lists the offset binary codes for this circuit.
. Table 2
REF
DAC LATCH CONTENTS
ANALOG OUTPUT, V
OUT
MSB
LSB
Power-Supply Bypassing and
Ground Management
✕
+V
+V
0
(32,767 / 32,768)
1111 1111 1111 1111
1000 0000 0000 0001
1000 0000 0000 0000
0111 1111 1111 1111
0000 0000 0000 0000
REF
✕
(1 / 32,768)
REF
ꢁypass V
with a 0.1µF ceramic capacitor connected
DD
DD
between V
and GID. Mount the capacitor with short
leads close to the device (less than 0.25 inches).
✕
-V
(1 / 32,768)
REF
REF
1–MAX54
✕
-V
(32,768 / 32,768) = -V
REF
10 ______________________________________________________________________________________
+3V/+5V, Serial-Input,
Voltage-Output, 16-Bit DACs
1–MAX54
Functional Diagrams
V
V
DD
DD
RFB
INV
MAX5442
MAX5444
MAX5441
MAX5443
REF
CS
REF
CS
OUT
OUT
16-BIT DAC
16-BIT DAC
16-BIT DATA LATCH
16-BIT DATA LATCH
SCLK
DIN
SCLK
DIN
CONTROL
LOGIC
CONTROL
LOGIC
SERIAL INPUT REGISTER
SERIAL INPUT REGISTER
CLR
CLR
GND
GND
Ordering Information (continued)
PART
TEMP RANGE
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
8 µMAX
INL (LSB)
SUPPLY (V)
MAX5443ACUA
MAX5443AEUA
MAX5443ꢁCUA
MAX5443ꢁEUA
MAX5444ACUꢁ
MAX5444AEUꢁ
MAX5444ꢁCUꢁ
MAX5444ꢁEUꢁ
2
2
4
4
2
2
4
4
3
3
3
3
3
3
3
3
8 µMAX
8 µMAX
8 µMAX
10 µMAX
10 µMAX
10 µMAX
10 µMAX
_____________________Chip Information
Package Information
For the latest package outline information, go to
TRAISꢂSTOR COUIT: 2800
PROCESS: ꢁiCMOS
www.maxim-ic.com/packages.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
8 µMAX
U8-1
21-0036
21-0061
10 µMAX
U10-2
______________________________________________________________________________________ 11
+3V/+5V, Serial-Input,
Voltage-Output, 16-Bit DACs
Revision History
REVISION REVISION
DESCRIPTION
PAGES
CHANGED
NUMBER
DATE
0
2
10/00
10/07
ꢂnitial release
—
6
Changed timing diagram
1–MAX54
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. Io circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim ꢂntegrated Products
is a registered trademark of Maxim ꢂntegrated Products, ꢂnc.
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