AD AD5791 True 18-bit, voltage output dac â±0.5 lsb inl, â±0.5 lsb dnl Datasheet

True 18-Bit, Voltage Output DAC
±0.5 LSB INL, ±0.5 LSB DNL
AD5781
Data Sheet
FEATURES
FUNCTIONAL BLOCK DIAGRAM
VCC
VDD
VREFPF VREFPS
AD5781
IOVCC
A1
R1
RFB
RFB
INV
SDIN
INPUT
SHIFT
REGISTER
AND
CONTROL
LOGIC
SCLK
SYNC
SDO
18
DAC
REG
18
18-BIT
DAC
VOUT
6kΩ
LDAC
CLR
POWER-ON-RESET
AND CLEAR LOGIC
RESET
APPLICATIONS
6.8kΩ 6.8kΩ
DGND
VSS
AGND
VREFNF VREFNS
09092-001
Single 18-bit DAC, ±0.5 LSB INL
7.5 nV/√Hz noise spectral density
0.05 LSB long-term linearity stability
<0.05 ppm/°C temperature drift
1 µs settling time
1.4 nV-sec glitch impulse
Operating temperature range: −40°C to +125°C
20-lead TSSOP package
Wide power supply range of up to ±16.5 V
35 MHz Schmitt triggered digital interface
1.8 V compatible digital interface
Figure 1.
Medical instrumentation
Test and measurement
Industrial control
Scientific and aerospace instrumentation
Data acquisition systems
Digital gain and offset adjustment
Power supply control
Table 1. Complementary Devices
Part No.
AD8675
AD8676
ADA4898-1
Description
Ultraprecision, 36 V, 2.8 nV/√Hz rail-to-rail
output op amp
Ultraprecision, 36 V, 2.8 nV/√Hz dual rail-torail output op amp
High voltage, low noise, low distortion, unity
gain stable, high speed op amp
Table 2. Related Devices
Part No.
AD5791
AD5541A/AD5542A
Description
20-bit, 1 ppm accurate DAC
16-bit, 1 LSB accurate 5 V DAC
GENERAL DESCRIPTION
The AD57811 is a single 18-bit, unbuffered voltage output DAC
that operates from a bipolar supply of up to 33 V. The AD5781
accepts a positive reference input range of 5 V to VDD − 2.5 V and
a negative reference input range of VSS + 2.5 V to 0 V. The
AD5781 offers a relative accuracy specification of ±0.5 LSB
maximum, and operation is guaranteed monotonic with a ±0.5
LSB DNL maximum specification.
PRODUCT HIGHLIGHTS
1.
2.
3.
4.
5.
True 18-Bit Accuracy.
Wide Power Supply Range of Up to ±16.5 V.
−40°C to +125°C Operating Temperature Range.
Low 7.5 nV/√Hz Noise.
Low 0.05 ppm/°C Temperature Drift.
The part uses a versatile 3-wire serial interface that operates at
clock rates of up to 35 MHz and is compatible with standard
SPI, QSPI™, MICROWIRE™, and DSP interface standards. The
part incorporates a power-on reset circuit that ensures that the
DAC output powers up to 0 V and in a known output impedance
state and remains in this state until a valid write to the device
takes place. The part provides an output clamp feature that
places the output in a defined load state.
1
Protected by U.S. Patent No 7884747, and other patents are pending.
Rev. D
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AD5781
Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
DAC Architecture....................................................................... 19
Applications ....................................................................................... 1
Hardware Control Pins .............................................................. 20
Functional Block Diagram .............................................................. 1
On-Chip Registers ...................................................................... 21
General Description ......................................................................... 1
AD5781 Features ............................................................................ 24
Product Highlights ........................................................................... 1
Power-On to 0 V ......................................................................... 24
Revision History ............................................................................... 2
Configuring the AD5781 .......................................................... 24
Specifications..................................................................................... 3
DAC Output State ...................................................................... 24
Timing Characteristics ................................................................ 5
Linearity Compensation ............................................................ 24
Absolute Maximum Ratings ............................................................ 7
Output Amplifier Configuration.............................................. 24
ESD Caution .................................................................................. 7
Applications Information .............................................................. 26
Pin Configuration and Function Description .............................. 8
Typical Operating Circuit ......................................................... 26
Typical Performance Characteristics ............................................. 9
Evaluation Board ........................................................................ 26
Terminology .................................................................................... 17
Outline Dimensions ....................................................................... 27
Theory of Operation ...................................................................... 19
Ordering Guide .......................................................................... 27
REVISION HISTORY
7/13—Rev. C to Rev. D
8/11—Rev. 0 to Rev. A
Changes to t1 Test Conditions/Comments and Endnote 2 ......... 5
Deleted Figure 4 ................................................................................ 7
Deleted Daisy-Chain Operation Section ..................................... 20
Change to Features Section ..............................................................1
Changes to Specifications Section ...................................................3
Deleted t14 Parameter from Timing Specifications Section,
Table 4 .................................................................................................5
Changes to Figure 2 and Figure 3 ....................................................6
Changes to Figure 4 ...........................................................................7
Replaced Figure 42 and Figure 43 ................................................ 16
Added New Figure 44, Figure 45, and Figure 46, Renumbered
Sequentially ..................................................................................... 16
11/11—Rev. B to Rev. C
Added Figure 48; Renumbered Sequentially .............................. 17
Change to Ideal Transfer Function Equation.............................. 22
9/11—Rev. A to Rev. B
Added Patent Note ........................................................................... 1
Changes to Table 3 ............................................................................ 3
Changes to OPGND Description, Table 12 ................................ 23
7/10—Revision 0: Initial Version
Rev. D | Page 2 of 28
Data Sheet
AD5781
SPECIFICATIONS
VDD = +12.5 V to +16.5 V, VSS = −16.5 V to −12.5 V, VREFP = +10 V, VREFN = −10 V, VCC = +2.7 V to +5.5 V, IOVCC = +1.71 V to +5.5 V,
RL = unloaded, CL = unloaded, TMIN to TMAX, unless otherwise noted.
Table 3.
Parameter
STATIC PERFORMANCE 2
Resolution
Integral Nonlinearity Error (Relative
Accuracy)
Differential Nonlinearity Error
Min
18
−0.5
−0.5
−1
−4
−0.5
−0.5
−1
Linearity Error Long-Term Stability 5
Full-Scale Error
−1.75
−2.75
−5.25
−1
−1
−1.5
Full-Scale Error Temperature Coefficient3
Zero-Scale Error
−1.75
−2.5
−5.25
−1
−1
−1.5
Zero-Scale Error Temperature Coefficient3
Gain Error
Gain Error Temperature Coefficient3
R1, RFB Matching
OUTPUT CHARACTERISTICS3
Output Voltage Range
Output Slew Rate
Output Voltage Settling Time
Output Noise Spectral Density
Output Voltage Noise
−6
−10
−20
A, B Version 1
Typ
Max
±0.25
+0.5
±0.25
±0.5
±2
±0.25
±0.25
±0.5
0.04
0.05
0.03
±0.25
±0.062
±0.2
±0.25
+0.5
+1
+4
+0.5
+0.5
+1
±0.062
±0.2
±0.02
±0.025
±0.38
±0.19
±0.025
+1
+1.5
±0.38
±0.19
±0.04
±0.3
±0.4
±0.4
±0.04
0.01
+1
+1.5
VREFN
+1.75
+2.75
+5.25
+1
+1.75
+2.5
+5.25
+1
+6
+10
+20
VREFP
Unit
Test Conditions/Comments
Bits
LSB
B version, VREFP = +10 V, VREFN = −10 V
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
ppm FSR/°C
LSB
LSB
LSB
LSB
LSB
LSB
ppm FSR/°C
ppm FSR
ppm FSR
ppm FSR
ppm FSR/°C
%
50
1
V
V/µs
µs
1
7.5
7.5
7.5
1.1
µs
nV/√Hz
nV/√Hz
nV/√Hz
µV p-p
Rev. D | Page 3 of 28
B version, VREFP = +10 V, VREFN = 0 V 3
B version, VREFP = +5 V, VREFN = 0 V3
A version 4
VREFP = +10 V, VREFN = −10 V
VREFP = +10 V, VREFN = 0 V3
VREFP = +5 V, VREFN = 0 V3
After 500 hours at TA = 125°C
After 1000 hours at TA = 125°C
After 1000 hours t TA = 100°C
VREFP = +10 V, VREFN = −10 V3
VREFP = +10 V, VREFN = 0 V3
VREFP = +5 V, VREFN = 0 V3
VREFP = +10 V, VREFN = −10 V3,
TA = 0°C to 105°C
VREFP = 10 V, VREFN = 0 V3, TA = 0°C to 105°C
VREFP = 5 V, VREFN = 0 V3, TA = 0°C to 105°C
VREFP = +10 V, VREFN = −10 V3
VREFP = +10 V, VREFN = 0 V3
VREFP = +5 V, VREFN = 0 V3
VREFP = +10 V, VREFN = −10 V3,
TA = 0°C to 105°C
VREFP = 10 V, VREFN = 0 V3, TA = 0°C to 105°C
VREFP = 5 V, VREFN = 0 V3, TA = 0°C to 105°C
VREFP = +10 V, VREFN = −10 V3
VREFP = +10 V, VREFN = 0 V3
VREFP = +5 V, VREFN = 0 V3
Unbuffered output, 10 MΩ||20 pF load
10 V step to 0.02%, using AD845
buffer in unity-gain mode
125 code step to ±1 LSB 6
at 1 kHz, DAC code = midscale
at 10 kHz, DAC code = midscale
at 100 kHz, DAC code = midscale
DAC code = midscale, 0.1 Hz to
10 Hz bandwidth 7
AD5781
Parameter
Midscale Glitch Impulse
Data Sheet
Min
MSB Segment Glitch Impulse6
Output Enabled Glitch Impulse
Digital Feedthrough
DC Output Impedance (Normal Mode)
DC Output Impedance (Output
Clamped to Ground)
Spurious Free Dynamic Range
Total Harmonic Distortion
REFERENCE INPUTS3
VREFP Input Range
VREFN Input Range
DC Input Impedance
Input Capacitance
LOGIC INPUTS3
Input Current 8
Input Low Voltage, VIL
Input High Voltage, VIH
Pin Capacitance
LOGIC OUTPUT (SDO)3
Output Low Voltage, VOL
Output High Voltage, VOH
High Impedance Leakage Current
High Impedance Output Capacitance
POWER REQUIREMENTS
VDD
VSS
VCC
IOVCC
IDD
ISS
ICC
IOICC
DC Power Supply Rejection Ratio3, 9
AC Power Supply Rejection Ratio3
A, B Version 1
Typ
Max
3.1
1.7
1.4
9.1
3.6
1.9
45
0.4
3.4
6
100
97
5
VSS + 2.5 V
5
VDD − 2.5 V
0
Unit
nV-sec
nV-sec
nV-sec
nV-sec
nV-sec
nV-sec
nV-sec
nV-sec
kΩ
kΩ
Test Conditions/Comments
VREFP = +10 V, VREFN = −10 V
VREFP = +10 V, VREFN = 0 V
VREFP = +5 V, VREFN = 0 V
VREFP = +10 V, VREFN = −10 V, see Figure 42
VREFP = 10 V, VREFN = 0 V, see Figure 43
VREFP = 5 V, VREFN = 0 V, see Figure 44
On removal of output ground clamp
dB
dB
1 kHz tone, 10 kHz sample rate
1 kHz tone, 10 kHz sample rate
V
6.6
kΩ
15
pF
−1
+1
0.3 × IOVCC
µA
V
V
pF
0.4
V
±1
µA
pF
VSS + 33
−2.5
5.5
5.5
5.2
4.9
900
140
V
V
V
V
mA
mA
µA
µA
µV/V
µV/V
dB
dB
0.7 × IOVCC
5
IOVCC − 0.5 V
3
VREFP, VREFN, code dependent,
typical at midscale code
VREFP, VREFN
IOVCC = 1.71 V to 5.5 V
IOVCC = 1.71 V to 5.5 V
IOVCC = 1.71 V to 5.5 V, sinking 1 mA
IOVCC = 1.71 V to 5.5 V, sourcing 1 mA
All digital inputs at DGND or IOVCC
7.5
VDD − 33
2.7
1.71
4.2
4
600
52
±0.6
±0.6
95
95
IOVCC ≤ VCC
SDO disabled
VDD ± 10%, VSS = 15 V
VSS ± 10%, VDD = 15 V
VDD ± 200 mV, 50 Hz/60 Hz, VSS = −15 V
VSS ± 200 mV, 50 Hz/60 Hz, VDD = 15 V
Temperature range: −40°C to +125°C, typical conditions: TA = 25°C, VDD = +15 V, VSS = −15 V, VREFP = +10 V, VREFN = −10 V.
Performance characterized with AD8676BRZ voltage reference buffers and AD8675ARZ output buffer.
3
Linearity error refers to both INL error and DNL error; either parameter can be expected to drift by the amount specified after the length of time specified.
4
Valid for all voltage reference spans.
5
Guaranteed by design and characterization, not production tested.
6
The AD5781 is configured in the bias compensation mode with a low-pass RC filter on the output. R = 300 Ω, C = 143 pF (total capacitance seen by the output buffer,
lead capacitance, and so forth).
7
Includes noise contribution from AD8676BRZ voltage reference buffers.
8
Current flowing in an individual logic pin.
9
Includes PSRR of AD8676BRZ voltage reference buffers.
1
2
Rev. D | Page 4 of 28
Data Sheet
AD5781
TIMING CHARACTERISTICS
VCC = 2.7 V to 5.5 V; all specifications TMIN to TMAX, unless otherwise noted.
Table 4.
Parameter
t1 2
t2
t3
t4
t5
t6
t7
t8
t9
t10
t11
t12
t13
t14
t15
t16
t17
t18
t19
t20
t21
t22
1
2
Limit 1
IOVCC = 1.71 V to 3.3 V
IOVCC = 3.3 V to 5.5 V
40
28
92
60
15
10
9
5
5
5
2
2
48
40
8
6
9
7
12
7
13
10
20
16
14
11
130
130
130
130
50
50
140
140
0
0
65
60
62
45
0
0
35
35
150
150
Unit
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns typ
ns typ
ns min
ns typ
ns min
ns max
ns max
ns min
ns typ
ns typ
Test Conditions/Comments
SCLK cycle time
SCLK cycle time (readback mode)
SCLK high time
SCLK low time
SYNC to SCLK falling edge setup time
SCLK falling edge to SYNC rising edge hold time
Minimum SYNC high time
SYNC rising edge to next SCLK falling edge ignore
Data setup time
Data hold time
LDAC falling edge to SYNC falling edge
SYNC rising edge to LDAC falling edge
LDAC pulse width low
LDAC falling edge to output response time
SYNC rising edge to output response time (LDAC tied low)
CLR pulse width low
CLR pulse activation time
SYNC falling edge to first SCLK rising edge
SYNC rising edge to SDO tristate (CL = 50 pF)
SCLK rising edge to SDO valid (CL = 50 pF)
SYNC rising edge to SCLK rising edge ignore
RESET pulse width low
RESET pulse activation time
All input signals are specified with tR = tF = 1 ns/V (10% to 90% of IOVCC) and timed from a voltage level of (VIL + VIH)/2.
Maximum SCLK frequency is 35 MHz for write mode and 16 MHz for readback mode.
Rev. D | Page 5 of 28
AD5781
Data Sheet
t7
t1
SCLK
1
2
24
t3
t6
t2
t4
t5
SYNC
t9
t8
SDIN
DB23
DB0
t10
t12
t11
LDAC
t13
VOUT
t14
VOUT
t15
CLR
t16
VOUT
t21
RESET
09092-002
t22
VOUT
Figure 2. Write Mode Timing Diagram
t1
t17
SCLK
1
2
24
t3
t6
t20
t7
1
2
24
t2
t5
t4
t5
t17
SYNC
SDIN
t9
DB23
DB0
INPUT WORD SPECIFIES
REGISTER TO BE READ
NOP CONDITION
t18
t19
DB23
SDO
REGISTER CONTENTS CLOCKED OUT
Figure 3. Readback Mode Timing Diagram
Rev. D | Page 6 of 28
DB0
09092-003
t8
Data Sheet
AD5781
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted. Transient currents of up to
100 mA do not cause SCR latch-up.
Table 5.
Parameter
VDD to AGND
VSS to AGND
VDD to VSS
VCC to DGND
IOVCC to DGND
Digital Inputs to DGND
VOUT to AGND
VREFPF to AGND
VREFPS to AGND
VREFNF to AGND
VREFNS to AGND
DGND to AGND
Operating Temperature Range, TA
Industrial
Storage Temperature Range
Maximum Junction Temperature,
TJ max
Power Dissipation
TSSOP Package
θJA Thermal Impedance
θJC Thermal Impedance
Lead Temperature
Soldering
ESD (Human Body Model)
Rating
−0.3 V to +34 V
−34 V to +0.3 V
−0.3 V to +34 V
−0.3 V to +7 V
−0.3 V to VCC + 3 V or +7 V
(whichever is less)
−0.3 V to IOVCC + 0.3 V or
+7 V (whichever is less)
−0.3 V to VDD + 0.3 V
−0.3 V to VDD + 0.3 V
−0.3 V to VDD + 0.3 V
VSS − 0.3 V to +0.3 V
VSS − 0.3 V to +0.3 V
−0.3 V to +0.3 V
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.
This device is a high performance integrated circuit with an
ESD rating of 1.5 kV, and it is ESD sensitive. Proper precautions
should be taken for handling and assembly.
ESD CAUTION
−40°C to + 125°C
−65°C to +150°C
150°C
(TJ max − TA)/θJA
143°C/W
45°C/W
JEDEC industry standard
J-STD-020
1.5 kV
Rev. D | Page 7 of 28
AD5781
Data Sheet
PIN CONFIGURATION AND FUNCTION DESCRIPTION
INV
1
20
RFB
VOUT
2
19
AGND
VREFPS
3
18
VSS
VREFPF
4
AD5781
VDD
5
RESET
6
15
DGND
CLR
7
14
SYNC
LDAC
8
13
SCLK
VCC
9
12
SDIN
IOVCC 10
11
SDO
09092-005
17 VREFNS
TOP VIEW
(Not to Scale) 16
VREFNF
Figure 4. Pin Configuration
Table 6. Pin Function Descriptions
Pin No.
1
2
3
Mnemonic
INV
VOUT
VREFPS
4
VREFPF
5
VDD
6
7
RESET
CLR
8
LDAC
9
10
VCC
IOVCC
11
12
SDO
SDIN
13
SCLK
14
SYNC
15
16
DGND
VREFNF
17
VREFNS
18
VSS
19
20
AGND
RFB
Description
Connection to Inverting Input of External Amplifier. See the AD5781 Features section for further details.
Analog Output Voltage.
Positive Reference Sense Voltage Input. A voltage range of 5 V to VDD − 2.5 V can be connected. A unity gain amplifier
must be connected at this pin, in conjunction with the VREFPF pin. See the AD5781 Features section for further details.
Positive Reference Force Voltage Input. A voltage range of 5 V to VDD − 2.5 V can be connected. A unity gain amplifier
must be connected at these pin, in conjunction with the VREFPS pin. See AD5781 Features section for further details.
Positive Analog Supply Connection. A voltage range of 7.5 V to 16.5 V can be connected. VDD should be decoupled to
AGND.
Active Low Reset Logic Input Pin. Asserting this pin returns the AD5781 to its power-on status.
Active Low Clear Logic Input Pin. Asserting this pin sets the DAC register to a user defined value (see Table 13) and
updates the DAC output. The output value depends on the DAC register coding that is being used, either binary or twos
complement.
Active Low Load DAC Logic Input Pin. This is used to update the DAC register and, consequently, the analog output.
When tied permanently low, the output is updated on the rising edge of SYNC. If LDAC is held high during the write
cycle, the input register is updated, but the output update is held off until the falling edge of LDAC. The LDAC pin
should not be left unconnected.
Digital Supply Connection. A voltage in the range of 2.7 V to 5.5 V can be connected. VCC should be decoupled to DGND.
Digital Interface Supply Pin. Digital threshold levels are referenced to the voltage applied to this pin. A voltage range of
1.71 V to 5.5 V can be connected. IOVCC should not be allowed to exceed VCC.
Serial Data Output Pin. Data is clocked out on the rising edge of the serial clock input.
Serial Data Input Pin. This device has a 24-bit shift register. Data is clocked into the register on the falling edge of the
serial clock input.
Serial Clock Input. Data is clocked into the input shift register on the falling edge of the serial clock input. Data can be
transferred at clock rates of up to 35 MHz.
Active Low Digital Interface Synchronization Input Pin. This is the frame synchronization signal for the input data. When
SYNC is low, it enables the input shift register, and data is then transferred in on the falling edges of the following clocks.
The input shift register is updated on the rising edge of SYNC.
Ground Reference Pin for Digital Circuitry.
Negative Reference Force Voltage Input. A voltage range of VSS + 2.5 V to 0 V can be connected. A unity gain amplifier
must be connected at this pin, in conjunction with the VREFNS pin. See the AD5781 Features section for further details.
Negative Reference Sense Voltage Input. A voltage range of VSS + 2.5 V to 0 V can be connected. A unity gain amplifier
must be connected at these pin, in conjunction with the VREFNF pin. See the AD5781 Features section for further details.
Negative Analog Supply Connection. A voltage range of −16.5 V to −2.5 V can be connected. VSS should be decoupled to
AGND.
Ground Reference Pin for Analog Circuitry.
Feedback Connection for External Amplifier. See the AD5781 Features section for further details.
Rev. D | Page 8 of 28
Data Sheet
AD5781
TYPICAL PERFORMANCE CHARACTERISTICS
0.5
0.5
TA = +125°C
TA = +25°C
TA = –40°C
0.3
0.2
0.2
INL ERROR (LSB)
0.3
0.1
0
–0.1
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
VREFP = +10V
VREFN = –10V
VDD = +15V
VSS = –15V
–0.3
–0.4
50000
100000
150000
DAC CODE
–0.1
–0.4
200000
250000
–0.5
0
50000
150000
100000
DAC CODE
200000
250000
Figure 8. Integral Nonlinearity Error vs. DAC Code, ±10 V Span, X2 Gain Mode
0.5
0.5
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
TA = +125°C
TA = +25°C
TA = –40°C
0.3
0.2
0.2
DNL ERROR (LSB)
0.3
0.1
0
–0.1
–0.2
VREFP = +10V
VREFN = 0V
VDD = +15V
VSS = –15V
50000
0
–0.1
–0.2
–0.4
–0.5
0
0.1
100000
150000
DAC CODE
200000
250000
–0.5
0
Figure 6. Integral Nonlinearity Error vs. DAC Code, +10 V Span
200000
250000
0.5
TA = +125°C
TA = +25°C
TA = –40°C
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
VREFP = +10V
VREFN = 0V
VDD = +15V
VSS = –15V
0.4
0.3
0.4
0.2
DNL ERROR (LSB)
0.6
0.2
0
–0.2
TA = +125°C
TA = +25°C
TA = –40°C
0.1
0
–0.1
–0.2
–0.3
–0.4
200000
250000
–0.5
09092-008
–0.4 AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
–0.6 VREFP = +5V
VREFN = 0V
–0.8 VDD = +15V
VSS = –15V
–1.0
0
50000
100000
150000
DAC CODE
100000
150000
DAC CODE
Figure 9. Differential Nonlinearity Error vs. DAC Code, ±10 V Span
1.0
0.8
50000
09092-010
–0.4
TA = +125°C
TA = +25°C
TA = –40°C
–0.3
09092-007
–0.3
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
VREFP = +10V
VREFN = –10V
VDD = +15V
VSS = –15V
0.4
0
Figure 7. Integral Nonlinearity Error vs. DAC Code, +5 V Span
50000
100000
150000
DAC CODE
200000
250000
09092-011
0.4
INL ERROR (LSB)
0
–0.3
Figure 5. Integral Nonlinearity Error vs. DAC Code, ±10 V Span
INL ERROR (LSB)
0.1
–0.2
–0.5
0
TA = +25°C
TA = –40°C
TA = +125°C
09092-009
–0.2
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
VREFP = +10V
VREFN = 0V
VDD = +15V
VSS = –15V
0.4
09092-006
INL ERROR (LSB)
0.4
Figure 10. Differential Nonlinearity Error vs. DAC Code, +10 V Span
Rev. D | Page 9 of 28
AD5781
0.5
Data Sheet
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
VREFP = +5V
VREFN = 0V
0.4
0.3
0.3
TA = +125°C
TA = +25°C
TA = –40°C
0.2
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
VDD = +15V
VSS = –15V
DNL ERROR (LSB)
DNL ERROR (LSB)
0.1
0.2
0.1
0
–0.1
–0.2
0
–0.1
–0.2
–0.3
–0.3
100000
150000
DAC CODE
200000
250000
–0.5
–55
Figure 11. Differential Nonlinearity Error vs. DAC Code, +5 V Span
85
105
125
0.10
0
–0.1
0.04
0.02
–0.2
0
–0.3
–0.02
–0.4
–0.04
–0.5
50000
100000
150000
DAC CODE
200000
250000
TA = 25°C
VREFP = +10V
VREFN = –10V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
0.06
INL MIN
–0.06
12.5
Figure 12. Differential Nonlinearity Error vs. DAC Code, ±10 V Span,
X2 Gain Mode
13.0
13.5
14.0
14.5
15.0
VDD/|VSS| (V)
15.5
16.0
16.5
09092-016
0.1
0
INL MAX
0.08
INL ERROR (LSB)
0.2
0.12
09092-013
Figure 15. Integral Nonlinearity Error vs. Supply Voltage, ±10 V Span
0.5
0.4
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
VDD = +15V
VSS = –15V
0.3
INL MAX
0.2
INL ERROR (LSB)
0.2
0.1
0
–0.1
–0.2
0.1
0
TA = 25°C
VREFP = +5V
VREFN = 0V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
–0.1
–0.3
–0.5
–55
–35
–15
+10V SPAN MAX INL
±10V SPAN MIN INL
+5V SPAN MIN INL
5
25
45
65
TEMPERATURE (°C)
85
–0.2
INL MIN
105
125
09092-014
±10V SPAN MAX INL
+5V SPAN MAX INL
+10V SPAN MIN INL
–0.4
Figure 13. Integral Nonlinearity Error vs. Temperature
–0.3
7.5
8.5
9.5
10.5
–2.5
–3.9
–5.3
–6.7
11.5 12.5 13.5 14.5 15.5 16.5
VDD (V)
–9.1 –10.5 –12.9 –14.2 –15.5 –16.5
VSS (V)
09092-017
DNL ERROR (LSB)
0.3
INL ERROR (LSB)
5
25
45
65
TEMPERATURE (°C)
0.14
TA = +25°C
TA = –40°C
TA = +125°C
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
VREFP = +10V
VREFN = 0V
VDD = +15V
VSS = –15V
0.4
0.3
–15
Figure 14. Differential Nonlinearity Error vs. Temperature
0.5
0.4
–35
+10V SPAN MAX DNL
±10V SPAN MIN DNL
+5V SPAN MIN DNL
09092-015
50000
09092-012
–0.5
0
±10V SPAN MAX DNL
+5V SPAN MAX DNL
+10V SPAN MIN DNL
–0.4
VDD = +15V
VSS = –15V
–0.4
Figure 16. Integral Nonlinearity Error vs. Supply Voltage, +5 V Span
Rev. D | Page 10 of 28
Data Sheet
AD5781
0.14
0.08
0.06
ZERO-SCALE ERROR (LSB)
TA = 25°C
VREFP = +10V
VREFN = –10V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
–0.02
–0.04
13.0
13.5
14.0
14.5
15.0
VDD/|VSS| (V)
15.5
16.0
16.5
09092-018
–0.08
12.5
0.04
0
7.5
8.5
9.5
10.5
–2.5
–3.9
–5.3
–6.7
11.5 12.5 13.5 14.5 15.5 16.5
VDD (V)
–9.1 –10.5 –12.9 –14.2 –15.5 –16.5
VSS (V)
Figure 20. Zero-Scale Error vs. Supply Voltage, +5 V Span
Figure 17. Differential Nonlinearity Error vs. Supply Voltage, ±10 V Span
0.05
0.10
0.04
0.05
MID-SCALE ERROR (LSB)
DNL MAX
0
DNL ERROR (LSB)
0.06
0.02
DNL MIN
–0.06
0.08
09092-021
0
0.10
TA = 25°C
VREFP = +5V
VREFN = 0V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
–0.05
–0.10
–0.15
DNL MIN
–0.20
0.03
TA = 25°C
VREFP = +10V
VREFN = –10V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
0.02
0.01
0
–0.01
–0.02
8.5
9.5
10.5
–2.5
–3.9
–5.3
–6.7
11.5 12.5 13.5 14.5 15.5 16.5
VDD (V)
–9.1 –10.5 –12.9 –14.2 –15.5 –16.5
VSS (V)
–0.03
12.5
13.0
13.5
09092-019
–0.25
7.5
Figure 18. Differential Nonlinearity Error vs. Supply Voltage, +5 V Span
14.0
14.5
15.0
VDD/|VSS| (V)
15.5
16.0
16.5
09092-022
DNL ERROR (LSB)
0.04
0.02
TA = 25°C
VREFP = +5V
VREFN = 0V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
0.12
DNL MAX
Figure 21. Midscale Error vs. Supply Voltage, ±10 V Span
0.14
0.05
0.12
0.06
0.04
0.02
0
12.5
TA = 25°C
VREFP = +10V
VREFN = –10V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
13.0
13.5
14.0
14.5
15.0
VDD/|VSS| (V)
15.5
16.0
16.5
Figure 19. Zero-Scale Error vs. Supply Voltage, ±10 V Span
–0.05
–0.10
–0.15
TA = 25°C
VREFP = +5V
VREFN = 0V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
–0.20
7.5
8.5
9.5
10.5
–2.5
–3.9
–5.3
–6.7
11.5 12.5 13.5 14.5 15.5 16.5
VDD (V)
–9.1 –10.5 –12.9 –14.2 –15.5 –16.5
VSS (V)
Figure 22. Midscale Error vs. Supply Voltage, +5 V Span
Rev. D | Page 11 of 28
09092-023
MID-SCALE ERROR (LSB)
0.08
09092-020
ZERO-SCALE ERROR (LSB)
0
0.10
AD5781
Data Sheet
0.10
–0.015
TA = 25°C
VREFP = +5V
VREFN = 0V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
0.05
GAIN ERROR (ppm FSR)
0
–0.025
–0.030
–0.035
TA = 25°C
VREFP = +10V
VREFN = –10V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
–0.045
12.5
13.0
13.5
15.0
14.5
14.0
VDD/|VSS| (V)
15.5
–0.10
–0.15
–0.20
–0.25
–0.35
16.0
16.5
–0.40
7.5
8.5
9.5
10.5
–2.5
–3.9
–5.3
–6.7
11.5 12.5 13.5 14.5 15.5 16.5
VDD (V)
–9.1 –10.5 –12.9 –14.2 –15.5 –16.5
VSS (V)
09092-027
–0.040
–0.05
–0.30
09092-024
FULL-SCALE ERROR (LSB)
–0.020
Figure 26. Gain Error vs. Supply Voltage, +5 V Span
Figure 23. Full-Scale Error vs. Supply Voltage, ±10 V Span
0.15
0.07
0.06
0.03
0.02
0.01
TA = 25°C
VREFP = +5V
VREFN = 0V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
0
–0.02
7.5
8.5
9.5
10.5
–2.5
–3.9
–5.3
–6.7
0.05
0
TA = 25°C
VDD = +15V
VSS = –15V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
–0.05
–0.10
11.5 12.5 13.5 14.5 15.5 16.5
VDD (V)
–9.1 –10.5 –12.9 –14.2 –15.5 –16.5
VSS (V)
–0.15
5.0
INL MIN
5.5
6.0
6.5
7.0
7.5
8.0
VREFP /|VREFN | (V)
8.5
9.0
9.5
10.0
09092-028
INL ERROR (LSB)
0.04
–0.01
Figure 27. Integral Nonlinearity Error vs. Reference Voltage
Figure 24. Full-Scale Error vs. Supply Voltage, +5 V Span
–0.30
0.10
TA = 25°C
VREFP = +10V
VREFN = –10V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
–0.35
0.05
DNL ERROR (LSB)
–0.40
DNL MAX
–0.45
–0.50
0
–0.05
TA = 25°C
VDD = +15V
VSS = –15V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
–0.55
–0.10
–0.60
13.0
13.5
14.0
14.5
15.0
VDD/|VSS| (V)
15.5
16.0
16.5
Figure 25. Gain Error vs. Supply Voltage, ±10 V Span
–0.15
5.0
5.5
6.0
6.5
7.0
7.5
8.0
VREFP /|VREFN | (V)
8.5
9.0
9.5
10.0
Figure 28. Differential Nonlinearity Error vs. Reference Voltage
Rev. D | Page 12 of 28
09092-029
DNL MIN
–0.65
12.5
09092-026
GAIN ERROR (ppm FSR)
INL MAX
09092-025
FULL-SCALE ERROR (LSB)
0.10
0.05
Data Sheet
AD5781
–0.30
0.16
TA = 25°C
VDD = +15V
VSS = –15V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
0.14
0.12
GAIN ERROR (ppm FSR)
ZERO-SCALE ERROR (LSB)
–0.35
0.10
0.08
0.06
TA = 25°C
VDD = +15V
VSS = –15V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
0.04
–0.40
–0.45
–0.50
–0.55
6.0
6.5
7.0
7.5
8.0
VREFP /|VREFN | (V)
8.5
9.0
9.5
10.0
–0.60
5.0
0.03
0.3
0.02
0.2
0.01
0
–0.01
TA = 25°C
VDD = +15V
VSS = –15V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
–0.02
–0.03
–0.04
5.5
6.0
6.5
7.0
7.5
8.0
VREFP /|VREFN | (V)
8.5
9.0
9.5
10.0
8.5
9.0
9.5
10.0
0
–0.1
–0.2
–0.3
–0.4
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
VDD = +15V
VSS = –15V
VREFP = +10V
VREFN = –15V
–0.6
–55
–35
–15
5
25
45
65
TEMPERATURE (°C)
85
105
125
Figure 33. Full-Scale Error vs. Temperature
0.40
TA = 25°C
VDD = +15V
VSS = –15V
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
0.02
0.01
0
–0.01
–0.02
0.30
0.25
0.20
0.15
0.10
0.05
6.0
6.5
7.0
7.5
8.0
VREFP /|VREFN | (V)
8.5
9.0
9.5
10.0
09092-032
–0.03
5.5
±10V SPAN
+10V SPAN
±5V SPAN
0.35
MID-SCALE ERROR (LSB)
0.03
0
–55
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
VDD = +15V
VSS = –15V
VREFP = +10V
VREFN = –15V
–35
–15
5
25
45
65
TEMPERATURE (°C)
85
Figure 34. Midscale Error vs. Temperature
Figure 31. Full-Scale Error vs. Reference Voltage
Rev. D | Page 13 of 28
105
125
09092-035
0.04
FULL-SCALE ERROR (LSB)
8.0
7.0
7.5
VREFP /|VREFN | (V)
±10V SPAN
+10V SPAN
±5V SPAN
Figure 30. Midscale Error vs. Reference Voltage
–0.04
5.0
6.5
0.1
–0.5
09092-031
–0.05
5.0
6.0
Figure 32. Gain Error vs. Reference Voltage
FULL-SCALE ERROR (LSB)
MID-SCALE ERROR (LSB)
Figure 29. Zero-Scale Error vs. Reference Voltage
5.5
09092-034
5.5
09092-030
0
5.0
09092-033
0.02
AD5781
Data Sheet
5
1.2
±10V SPAN
+10V SPAN
±5V SPAN
TA = 25°C
4
IDD
0.8
3
0.6
2
IDD, ISS (mA)
0.4
0.2
0
–0.2 AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
–0.4
VDD = +15V
VSS = –15V
–0.6
VREFP = +10V
–0.8 VREFN = –15V
–35
–15
0
–1
–3
ISS
–4
5
25
45
65
TEMPERATURE (°C)
85
105
125
–5
–20
–15
–10
–5
0
5
VDD, VSS (V)
10
15
20
Figure 38. Power Supply Currents vs. Power Supply Voltages
Figure 35. Zero-Scale Error vs. Temperature
4
3
GAIN ERROR (ppm FSR)
2
1
±10V SPAN
+10V SPAN
+5V SPAN
AD8676 REFERENCE BUFFERS
AD8675 OUTPUT BUFFER
VDD = +15V
VSS = –15V
VREFP = +10V
VREFN = –15V
0
VDD = +15V
VSS = –15V
VREFP = +10V
VREFN = –10V
AD8676 REFERENCE BUFFERS
OUTPUT UNBUFFERED
LOAD = 10MΩ||20pF
3
–1
–2
–4
–35
–15
5
25
45
65
TEMPERATURE (°C)
85
105
125
4
09092-037
–5
–55
CH3 5V
Figure 36. Gain Error vs. Temperature
900
TA = 25°C
800
700
200ns
Figure 39. Rising Full-Scale Voltage Step
IOVCC = 5V, LOGIC VOLTAGE
INCREASING
IOVCC = 5V, LOGIC VOLTAGE
DECREASING
IOVCC = 3V, LOGIC VOLTAGE
INCREASING
IOVCC = 3V, LOGIC VOLTAGE
DECREASING
VDD = +15V
VSS = –15V
VREFP = +10V
VREFN = –10V
AD8676 REFERENCE BUFFERS
OUTPUT UNBUFFERED
LOAD = 10MΩ||20pF
500
3
400
300
100
4
0
0
1
2
3
4
LOGIC INPUT VOLTAGE (V)
5
6
CH3 5V
Figure 37. IOICC vs. Logic Input Voltage
CH4 5V
200ns
Figure 40. Falling Full-Scale Voltage Step
Rev. D | Page 14 of 28
09092-041
200
09092-038
IOICC (µA)
600
CH4 5V
09092-040
–3
09092-039
–1.0
–55
1
–2
09092-036
ZERO-SCALE ERROR (LSBs)
1.0
Data Sheet
AD5781
10.8
3.0
±10V VREF
OUTPUT GAIN OF 1
BIAS COMPENSATION MODE
20pF COMPENSATION CAPACITOR
RC LOW-PASS FILTER
10.4
10.2
10.0
9.8
9.6
2.2
NEGATIVE CODE
CHANGE
POSITIVE CODE
CHANGE
1.8
1.4
1.0
0.6
0.2
2
3
4
5
TIME (µs)
–0.2
09092-061
1
16384
65536
114688
163840
212992
262144
311296
360448
409600
458752
507904
557056
606208
655360
704512
753664
802816
851968
901120
950272
999424
0
09092-063
9.4
CODE
Figure 44. 6 MSB Segment Glitch Energy for 5 V VREF
Figure 41. 125 Code Step Settling Time
40
10
NEGATIVE CODE
CHANGE
30
7
20
6
5
±10V VREF
OUTPUT GAIN OF 1
BIAS COMPENSATION MODE
20pF COMPENSATION CAPACITOR
RC LOW-PASS FILTER
POSITIVE CODE
CHANGE
4
10
0
3
2
CX = 143pF
CX = 143pF
CX = 143pF
CX = 143pF
–10
1
–20
–1.0
CODE
1.5
1.0
2.0
800
POSITIVE CODE
CHANGE
OUTPUT VOLTAGE (nV)
10V VREF
OUTPUT GAIN OF 1
BIAS COMPENSATION MODE
20pF COMPENSATION CAPACITOR
RC LOW-PASS FILTER
NEGATIVE CODE
CHANGE
2.0
1.5
1.0
TA = 25°C
VDD = +15V
V
600
SS = –15V
VREFP = +10V
VREFN = –10V
400
MID-SCALE CODE LOADED
OUTPUT UNBUFFERED
AD8676 REFERENCE BUFFERS
200
0
–200
–400
0.5
–600
0
CODE
0
09092-060
16384
65536
114688
163840
212992
262144
311296
360448
409600
458752
507904
557056
606208
655360
704512
753664
802816
851968
901120
950272
999424
OUTPUT GLITCH (nV–sec)
2.5
0.5
Figure 45. Midscale Peak-to-Peak Glitch for ±10 V
4.0
3.0
0
TIME (µs)
Figure 42. 6 MSB Segment Glitch Energy for ±10 V VREF
3.5
–0.5
09092-059
16384
65536
114688
163840
212992
262144
311296
360448
409600
458752
507904
557056
606208
655360
704512
753664
802816
851968
901120
950272
999424
0
+ 0pF
+ 220pF
+ 470pF
+ 1,000pF
09092-062
8
5V VREF
OUTPUT GAIN OF 1
BIAS COMPENSATION MODE
20pF COMPENSATION CAPACITOR
RC LOW-PASS FILTER
VOUT (mV)
OUTPUT GLITCH (nV–sec)
9
1
2
3
4
5
6
TIME (Seconds)
7
8
9
10
Figure 46. Voltage Output Noise, 0.1 Hz to 10 Hz Bandwidth
Figure 43. 6 MSB Segment Glitch Energy for 10 V VREF
Rev. D | Page 15 of 28
09092-044
VOUT (mV)
5V VREF
OUTPUT GAIN OF 1
BIAS COMPENSATION MODE
20pF COMPENSATION CAPACITOR
RC LOW-PASS FILTER
2.6
OUTPUT GLITCH (nV–sec)
10.6
AD5781
Data Sheet
NSD (nV/ Hz)
100
VDD = +15V
VSS = –15V
VREFP = +10V
VREFN = –10V
CODE = MIDSCALE
1
0.1
1
10
100
1k
FREQUENCY (Hz)
10k
100k
09092-064
10
Figure 47. Noise Spectral Density vs. Frequency
350
TA = 25°C
VDD = +15V
VSS = –15V
VREFP = +10V
VREFN = –10V
AD8675 OUTPUT BUFFER
250
200
150
100
50
0
–50
–1
0
1
2
3
TIME (µs)
4
5
6
09092-049
OUTPUT VOLTAGE (mV)
300
Figure 48. Glitch Impulse on Removal of Output Clamp
Rev. D | Page 16 of 28
Data Sheet
AD5781
TERMINOLOGY
Relative Accuracy
Relative accuracy, or integral nonlinearity (INL), is a measure of
the maximum deviation, in LSB, from a straight line passing
through the endpoints of the DAC transfer function. A typical
INL error vs. code plot is shown in Figure 5.
Differential Nonlinearity (DNL)
Differential nonlinearity is the difference between the measured
change and the ideal 1 LSB change between any two adjacent
codes. A specified differential nonlinearity of ±1 LSB maximum
ensures monotonicity. This DAC is guaranteed monotonic. A
typical DNL error vs. code plot is shown in Figure 9.
Linearity Error Long-Term Stability
Linearity error long-term stability is a measure of the stability of
the linearity of the DAC over a long period of time. It is
specified in LSB for a time period of 500 hours and 1000 hours
at an elevated ambient temperature.
Zero-Scale Error
Zero-scale error is a measure of the output error when zero-scale
code (0x00000) is loaded to the DAC register. Ideally, the output
voltage should be VREFNS. Zero-scale error is expressed in LSBs.
Zero-Scale Error Temperature Coefficient
Zero-scale error temperature coefficient is a measure of the
change in zero-scale error with a change in temperature. It is
expressed in ppm FSR/°C.
Full-Scale Error
Full-scale error is a measure of the output error when full-scale
code (0x3FFFF) is loaded to the DAC register. Ideally, the
output voltage should be VREFPS − 1 LSB. Full-scale error is
expressed in LSBs.
Full-Scale Error Temperature Coefficient
Full-scale error temperature coefficient is a measure of the
change in full-scale error with a change in temperature. It is
expressed in ppm FSR/°C.
Gain Error
Gain error is a measure of the span error of the DAC. It is the
deviation in slope of the DAC transfer characteristic from ideal,
expressed in ppm of the full-scale range.
Gain Error Temperature Coefficient
Gain error temperature coefficient is a measure of the change in
gain error with a change in temperature. It is expressed in ppm
FSR/°C.
Midscale Error
Midscale error is a measure of the output error when midscale
code (0x20000) is loaded to the DAC register. Ideally, the output
voltage should be (VREFPS – VREFNS)/2 +VREFNS. Midscale error is
expressed in LSBs.
Midscale Error Temperature Coefficient
Midscale error temperature coefficient is a measure of the
change in mid-scale error with a change in temperature. It is
expressed in ppm FSR/°C.
Output Slew Rate
Slew rate is a measure of the limitation in the rate of change of
the output voltage. The slew rate of the AD5781 output voltage
is determined by the capacitive load presented to the VOUT pin.
The capacitive load in conjunction with the 3.4 kΩ output
impedance of the AD5781 set the slew rate. Slew rate is
measured from 10% to 90% of the output voltage change and is
expressed in V/µs.
Output Voltage Settling Time
Output voltage settling time is the amount of time it takes for
the output voltage to settle to a specified level for a specified
change in voltage. For fast settling applications, a high speed
buffer amplifier is required to buffer the load from the 3.4 kΩ
output impedance of the AD5781, in which case, it is the
amplifier that determines the settling time.
Digital-to-Analog Glitch Impulse
Digital-to-analog glitch impulse is the impulse injected into the
analog output when the input code in the DAC register changes
state. It is specified as the area of the glitch in nV-sec and is
measured when the digital input code is changed by 1 LSB at
the major carry transition (see Figure 42).
Output Enabled Glitch Impulse
Output enabled glitch impulse is the impulse injected into the
analog output when the clamp to ground on the DAC output is
removed. It is specified as the area of the glitch in nV-sec (see
Figure 48).
Digital Feedthrough
Digital feedthrough is a measure of the impulse injected into
the analog output of the DAC from the digital inputs of the
DAC but is measured when the DAC output is not updated. It is
specified in nV-sec and measured with a full-scale code change
on the data bus, that is, from all 0s to all 1s, and vice versa.
Spurious Free Dynamic Range (SFDR)
Spurious free dynamic range is the usable dynamic range of a
DAC before spurious noise interferes or distorts the fundamental
signal. It is measured by the difference in amplitude between the
fundamental and the largest harmonically or nonharmonically
related spur from dc to full Nyquist bandwidth (half the DAC
sampling rate, or fS/2). SFDR is measured when the signal is a
digitally generated sine wave.
Total Harmonic Distortion (THD)
Total harmonic distortion is the ratio of the rms sum of the
harmonics of the DAC output to the fundamental value. Only
the second to fifth harmonics are included.
Rev. D | Page 17 of 28
AD5781
Data Sheet
DC Power Supply Rejection Ratio.
DC power supply rejection ratio is a measure of the rejection of
the output voltage to dc changes in the power supplies applied
to the DAC. It is measured for a given dc change in power
supply voltage and is expressed in µV/V.
AC Power Supply Rejection Ratio (AC PSRR)
AC power supply rejection ratio is a measure of the rejection of
the output voltage to ac changes in the power supplies applied
to the DAC. It is measured for a given amplitude and frequency
change in power supply voltage and is expressed in decibels.
Rev. D | Page 18 of 28
Data Sheet
AD5781
THEORY OF OPERATION
R
R
2R
R
VOUT
2R
2R ..................... 2R
2R
2R .......... 2R
S0
S1 ..................... S11
E62
E61.......... E0
VREFPF
VREFPS
VREFNF
VREFNS
12-BIT R-R LADDER
DAC ARCHITECTURE
09092-053
The AD5781 is a high accuracy, fast settling, single, 18-bit,
serial input, voltage output DAC. It operates from a VDD supply
voltage of 7.5 V to 16.5 V and a VSS supply of −16.5 V to −2.5 V.
Data is written to the AD5781 in a 24-bit word format via a 3-wire
serial interface. The AD5781 incorporates a power-on reset
circuit that ensures the DAC output powers up to 0 V with the
VOUT pin clamped to AGND through a ~6 kΩ internal resistor.
SIX MSBs DECODED INTO
63 EQUAL SEGMENTS
Figure 49. DAC Ladder Structure Serial Interface
The architecture of the AD5781 consists of two matched DAC
sections. A simplified circuit diagram is shown in Figure 49.
The six MSBs of the 18-bit data-word are decoded to drive 63
switches, E0 to E62. Each of these switches connects one of 63
matched resistors to either the VREFP or VREFN voltage. The
remaining 12 bits of the data-word drive the S0 to S11 switches
of a 12-bit voltage mode R-R ladder network.
The AD5781 has a 3-wire serial interface (SYNC, SCLK, and
SDIN) that is compatible with SPI, QSPI, and MICROWIRE
interface standards, as well as most DSPs (see Figure 2 for a
timing diagram).
Input Shift Register
The input shift register is 24 bits wide. Data is loaded into the
device MSB first as a 24-bit word under the control of a serial
clock input, SCLK, which can operate at up to 35 MHz. The
input register consists of a R/W bit, three address bits, and
twenty data bits as shown in Table 7. The timing diagram for
this operation is shown in Figure 2.
Table 7. Input Shift Register Format
MSB
DB23
R/W
DB22
DB21
Register address
DB20
Table 8. Decoding the Input Shift Register
R/W
X
0
0
0
0
1
1
1
1
1
Register Address
0
0
0
0
0
1
0
1
1
0
0
0
0
1
0
1
0
1
0
1
0
1
0
1
Description
No operation (NOP). Used in readback operations.
Write to the DAC register.
Write to the control register.
Write to the clearcode register.
Write to the software control register.
Read from the DAC register.
Read from the control register.
Read from the clearcode register.
X is don’t care.
Rev. D | Page 19 of 28
LSB
DB0
DB19
Register data
AD5781
Data Sheet
Standalone Operation
HARDWARE CONTROL PINS
The serial interface works with both a continuous and noncontinuous serial clock. A continuous SCLK source can be used
only if SYNC is held low for the correct number of clock cycles.
In gated clock mode, a burst clock containing the exact number
of clock cycles must be used, and SYNC must be taken high
after the final clock to latch the data. The first falling edge of
SYNC starts the write cycle. Exactly 24 falling clock edges must
be applied to SCLK before SYNC is brought high again. If
SYNC is brought high before the 24th falling SCLK edge, the
data written is invalid. If more than 24 falling SCLK edges are
applied before SYNC is brought high, the input data is also
invalid. The input shift register is updated on the rising edge of
SYNC. For another serial transfer to take place, SYNC must be
brought low again. After the end of the serial data transfer, data
is automatically transferred from the input shift register to the
addressed register. Once the write cycle is complete, the output
can be updated by taking LDAC low while SYNC is high.
Load DAC Function (LDAC)
After data has been transferred into the input register of the
DAC, there are two ways to update the DAC register and DAC
output. Depending on the status of both SYNC and LDAC, one
of two update modes is selected: synchronous DAC updating or
asynchronous DAC updating.
Synchronous DAC Update
In this mode, LDAC is held low while data is being clocked into
the input shift register. The DAC output is updated on the rising
edge of SYNC.
Asynchronous DAC Update
In this mode, LDAC is held high while data is being clocked
into the input shift register. The DAC output is asynchronously
updated by taking LDAC low after SYNC has been taken high.
The update now occurs on the falling edge of LDAC.
Readback
Reset Function (RESET)
The contents of all the on-chip registers can be read back via
the SDO pin. Table 8 outlines how the registers are decoded.
After a register has been addressed for a read, the next 24 clock
cycles clock the data out on the SDO pin. The clocks must be
applied while SYNC is low. When SYNC is returned high, the
SDO pin is placed in tristate. For a read of a single register, the
NOP function can be used to clock out the data. Alternatively,
if more than one register is to be read, the data of the first
register to be addressed can be clocked out at the same time the
second register to be read is being addressed. The SDO pin
must be enabled to complete a readback operation. The SDO
pin is enabled by default.
The AD5781 can be reset to its power-on state by two means:
either by asserting the RESET pin or by utilizing the software
RESET control function (see Table 14). If the RESET pin is not
used, it should be hardwired to IOVCC.
Asynchronous Clear Function (CLR)
The CLR pin is an active low clear that allows the output to be
cleared to a user defined value. The 18-bit clear code value is
programmed to the clearcode register (see Table 13). It is
necessary to maintain CLR low for a minimum amount of time
to complete the operation (see Figure 2). When the CLR signal
is returned high, the output remains at the clear value (if LDAC
is high) until a new value is loaded to the DAC register. The
output cannot be updated with a new value while the CLR pin is
low. A clear operation can also be performed by setting the CLR
bit in the software control register (see Table 14).
Rev. D | Page 20 of 28
Data Sheet
AD5781
Table 9. Hardware Control Pins Truth Table
LDAC
X1
X1
0
0
1
CLR
X1
X1
0
1
0
1
0
1
0
RESET
0
1
1
1
1
1
1
1
1
1
1
1
1
0
1
0
1
Function
The AD5781 is in reset mode. The device cannot be programmed.
The AD5781 is returned to its power-on state. All registers are set to their default values.
The DAC register is loaded with the clearcode register value, and the output is set accordingly.
The output is set according to the DAC register value.
The DAC register is loaded with the clearcode register value, and the output is set accordingly.
The output is set according to the DAC register value.
The output remains at the clear code value.
The output remains set according to the DAC register value.
The output remains at the clear code value.
The DAC register is loaded with the clearcode register value and the output is set accordingly.
The DAC register is loaded with the clearcode register value and the output is set accordingly.
The output remains at the clear code value.
The output is set according to the DAC register value.
X is don’t care.
ON-CHIP REGISTERS
DAC Register
Table 10 outlines how data is written to and read from the DAC register.
Table 10. DAC Register
MSB
DB23
R/W
DB22
R/W
0
1
LSB
DB21
DB20
DB19
Register address
0
18-bits of data
The following equation describes the ideal transfer function of the DAC:
(VREFP − VREFN ) × D + V
218 − 1
DB1
DB0
X1
X1
DAC register data
1
X is don’t care.
VOUT =
DB2
REFN
where:
VREFN is the negative voltage applied at the VREFNS input pin.
VREFP is the positive voltage applied at the VREFPS input pin.
D is the 18-bit code programmed to the DAC.
Rev. D | Page 21 of 28
AD5781
Data Sheet
Control Register
The control register controls the mode of operation of the AD5781.
Table 11. Control Register
MSB
DB23
LSB
DB22
R/W
R/W
DB21
DB20
DB19...DB11
DB10
DB9
DB8
Reserved
Reserved
LIN COMP
Register address
0
1
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
BIN/2sC
DACTRI
OPGND
RBUF
Reserved
Control register data
0
SDODIS
Table 12. Control Register Functions
Function
Reserved
RBUF
OPGND
DACTRI
BIN/2sC
SDODIS
LIN COMP
Description
These bits are reserved and should be programmed to zero.
Output amplifier configuration control.
0: internal amplifier, A1, is powered up and resistors RFB and R1 are connected in series as shown in Figure 52. This allows
an external amplifier to be connected in a gain of two configurations. See the AD5781 Features section for further details.
1: (default) internal amplifier, A1, is powered down and resistors RFB and R1 are connected in parallel as shown in Figure 51
so that the resistance between the RFB and INV pins is 3.4 kΩ, equal to the resistance of the DAC. This allows the RFB and INV
pins to be used for input bias current compensation for an external unity gain amplifier. See the AD5781 Features section
for further details.
Output ground clamp control.
0: DAC output clamp to ground is removed, and the DAC is placed in normal mode.
1: (default) DAC output is clamped to ground through a ~6 kΩ resistance, and the DAC is placed in tristate mode.
Resetting the part puts the DAC in OPGND mode, where the output ground clamp is enabled and the DAC is tristated.
Setting the OPGND bit to 1 in the control register overrules any write to the DACTRI bit
DAC tristate control.
0: DAC is in normal operating mode.
1: (default) DAC is in tristate mode.
DAC register coding select.
0: (default) DAC register uses twos complement coding.
1: DAC register uses offset binary coding.
SDO pin enable/disable control.
0: (default) SDO pin is enabled.
1: SDO pin is disabled (tristate).
Linearity error compensation for varying reference input spans. See the AD5781 Features section for further details.
0
0
0
0
(Default) reference input span up to 10 V.
1
1
0
0
Reference input span of 20 V.
Clearcode Register
The clearcode register sets the value to which the DAC output is set when the CLR pin or CLR bit is asserted. The output value depends
on the DAC coding that is being used, either binary or twos complement. The default register value is 0.
Table 13. Clearcode Register
MSB
DB23
R/W
DB22
R/W
0
1
LSB
DB21
DB20
Register address
1
DB19
DB2
Clearcode register data
1
18-bits of data
X is don’t care.
Rev. D | Page 22 of 28
DB1
DB0
X1
X1
Data Sheet
AD5781
Software Control Register
This is a write only register in which writing a 1 to a particular bit has the same effect as pulsing the corresponding pin low.
Table 14. Software Control Register
MSB
DB23
R/W
DB22
0
1
1
2
LSB
DB21
DB20
Register address
0
0
DB19
Reserved
DB3
DB2
DB1
Software control register data
RESET
CLR 1
DB0
LDAC 2
The CLR function has no effect if the LDAC pin is low.
The LDAC function has no effect if the CLR pin is low.
Table 15. Software Control Register Functions
Function
LDAC
CLR
RESET
Description
Setting this bit to 1 updates the DAC register and consequently the DAC output.
Setting this bit to 1 sets the DAC register to a user defined value (see Table 13) and updates the DAC output. The output
value depends on the DAC register coding that is being used, either binary or twos complement.
Setting this bit to 1 returns the AD5781 to its power-on state.
Rev. D | Page 23 of 28
AD5781
Data Sheet
AD5781 FEATURES
POWER-ON TO 0 V
Unity Gain Configuration
The AD5781 contains a power-on reset circuit that, as well as
resetting all registers to their default values, controls the output
voltage during power-up. Upon power-on, the DAC is placed in
tristate (its reference inputs are disconnected), and its output is
clamped to AGND through a ~6 kΩ resistor. The DAC remains
in this state until programmed otherwise via the control
register. This is a useful feature in applications where it is
important to know the state of the DAC output while it is in the
process of powering up.
Figure 50 shows an output amplifier configured for unity gain,
in this configuration the output spans from VREFN to VREFP.
VREFP
1/2 AD8676
VREFPF
A1
RFB
INV
18-BIT
DAC
VREFNF
AD8675,
ADA4898-1,
ADA4004-1
VOUT
VOUT
VREFNS
AD5781
1/2 AD8676
09092-054
After power-on, the AD5781 must be configured to put it into
normal operating mode before programming the output. To do
this, the control register must be programmed. The DAC is
removed from tristate by clearing the DACTRI bit, and the
output clamp is removed by clearing the OPGND bit. At this
point, the output goes to VREFN unless an alternative value is first
programmed to the DAC register.
VREFN
Figure 50. Output Amplifier in Unity Gain Configuration
DAC OUTPUT STATE
The DAC output can be placed in one of three states, controlled
by the DACTRI and OPGND bits of the control register, as
shown in Table 16.
Table 16. AD5781 Output State Truth Table
Output State
Normal operating mode.
Output is clamped via ~6 kΩ to AGND.
Output is in tristate.
Output is clamped via ~6 kΩ to AGND.
LINEARITY COMPENSATION
The integral nonlinearity (INL) of the AD5781 can vary
according to the applied reference voltage span; the LIN COMP
bits of the control register can be programmed to compensate
for this variation in INL. The specifications in this data sheet
are obtained with LIN COMP = 0000 for reference spans up to
and including 10 V and with LIN COMP = 1100 for a reference
span of 20 V. The default value of the LIN COMP bits is 0000.
A second unity gain configuration for the output amplifier is
one that removes an offset from the input bias currents of the
amplifier. It does this by inserting a resistance in the feedback
path of the amplifier that is equal to the output resistance of the
DAC. The DAC output resistance is 3.4 kΩ. By connecting R1
and RFB in parallel, a resistance equal to the DAC resistance is
available on-chip. Because the resistors are all on one piece of
silicon, they are temperature coefficient matched. To enable this
mode of operation, the RBUF bit of the control register must be set
to Logic 1. Figure 51 shows how the output amplifier is connected
to the AD5781. In this configuration, the output amplifier is in
unity gain and the output spans from VREFN to VREFP. This unity
gain configuration allows a capacitor to be placed in the
amplifier feedback path to improve dynamic performance.
VREFP
1/2 AD8676
VREFPF
VREFPS
OUTPUT AMPLIFIER CONFIGURATION
RFB
There are a number of different ways that an output amplifier
can be connected to the AD5781, depending on the voltage
references applied and the desired output voltage span.
R1 6.8kΩ RFB
INV
18-BIT
DAC
VREFNF
6.8kΩ
VOUT
VREFNS
AD5781
10pF
VOUT
AD8675,
ADA4898-1,
ADA4004-1
1/2 AD8676
VREFN
Figure 51. Output Amplifier in Unity Gain with Amplifier Input Bias Current
Compensation
Rev. D | Page 24 of 28
09092-055
OPGND
0
1
0
1
RFB
R1
6.8kΩ 6.8kΩ
CONFIGURING THE AD5781
DACTRI
0
0
1
1
VREFPS
Data Sheet
AD5781
Gain of Two Configuration
VREFP
Figure 52 shows an output amplifier configured for a gain of
two. The gain is set by the internal matched 6.8 kΩ resistors,
which are exactly twice the DAC resistance, having the effect
of removing an offset from the input bias current of the external
amplifier. In this configuration, the output spans from 2 × VREFN −
VREFP to VREFP. This configuration is used to generate a bipolar
output span from a single-ended reference input, with VREFN =
0 V. For this mode of operation, the RBUF bit of the control
register must be cleared to Logic 0.
1/2 AD8676
VREFPF
VREFPS
R1
A1
RFB
RFB
6.8kΩ 6.8kΩ
10pF
INV
VOUT
18-BIT
DAC
VREFNF
VOUT
VREFNS
AD5781
AD8675,
ADA4898-1,
ADA4004-1
VREFN = 0V
Figure 52. Output Amplifier in Gain of Two Configuration
Rev. D | Page 25 of 28
09092-056
1/2 AD8676
AD5781
Data Sheet
APPLICATIONS INFORMATION
09092-057
TYPICAL OPERATING CIRCUIT
Figure 53. Typical Operating Circuit
Figure 53 shows a typical operating circuit for the AD5781
using an AD8676 for reference buffers and an AD8675 as an
output buffer. To meet the specified linearity, force sense buffers
must be used on the reference inputs. Because the output
impedance of the AD5781 is 3.4 kΩ, an output buffer is
required for driving low resistive, high capacitive loads.
EVALUATION BOARD
An evaluation board is available for the AD5781 to aid
designers in evaluating the high performance of the part with
minimum effort. The AD5781 evaluation kit includes a
populated and tested AD5781 PCB. The evaluation board
interfaces to the USB port of a PC. Software is available with the
evaluation board to allow the user to easily program the
AD5781. The software runs on any PC that has Microsoft®
Windows® XP (SP2) or Vista (32 bits) installed. The EVALAD5781 data sheet is available, which gives full details on the
operation of the evaluation board
Rev. D | Page 26 of 28
Data Sheet
AD5781
OUTLINE DIMENSIONS
6.60
6.50
6.40
20
11
4.50
4.40
4.30
6.40 BSC
1
10
PIN 1
0.65
BSC
1.20 MAX
0.15
0.05
COPLANARITY
0.10
0.30
0.19
0.20
0.09
SEATING
PLANE
8°
0°
0.75
0.60
0.45
COMPLIANT TO JEDEC STANDARDS MO-153-AC
Figure 54. 20-Lead Thin Shrink Small Outline Package [TSSOP]
(RU-20)
Dimensions shown in millimeters
ORDERING GUIDE
Model 1
AD5781BRUZ
AD5781BRUZ-REEL7
AD5781ARUZ
AD5781ARUZ-REEL7
EVAL-AD5781SDZ
1
Temperature Range
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
INL
±0.5 LSB
±0.5 LSB
±4 LSB
±4 LSB
Z = RoHS Compliant Part.
Rev. D | Page 27 of 28
Package Description
20-Lead TSSOP
20-Lead TSSOP
20-Lead TSSOP
20-Lead TSSOP
Evaluation Board
Package Option
RU-20
RU-20
RU-20
RU-20
AD5781
Data Sheet
NOTES
©2010–2013 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D09092-0-7/13(D)
Rev. D | Page 28 of 28