Dual 8-/10-/12-Bit, High Bandwidth,
Multiplying DACs with Parallel Interface
Data Sheet
AD5428/AD5440/AD5447
Rev. C
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.
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Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 ©2004–2011 Analog Devices, Inc. All rights reserved.
FEATURES
10 MHz multiplying bandwidth
INL of ±0.25 LSB @ 8 bits
20-lead and 24-lead TSSOP packages
2.5 V to 5.5 V supply operation
±10 V reference input
21.3 MSPS update rate
Extended temperature range: −40°C to +125°C
4-quadrant multiplication
Power-on reset
0.5 μA typical current consumption
Guaranteed monotonic
Readback function
AD7528 upgrade (AD5428)
AD7547 upgrade (AD5447)
APPLICATIONS
Portable battery-powered applications
Waveform generators
Analog processing
Instrumentation applications
Programmable amplifiers and attenuators
Digitally controlled calibration
Programmable filters and oscillators
Composite video
Ultrasound
Gain, offset, and voltage trimming
GENERAL DESCRIPTION
The AD5428/AD5440/AD54471 are CMOS, 8-, 10-, and 12-bit,
dual-channel, current output digital-to-analog converters (DACs),
respectively. These devices operate from a 2.5 V to 5.5 V power
supply, making them suited to battery-powered and other
applications.
As a result of being manufactured on a CMOS submicron process,
they offer excellent 4-quadrant multiplication characteristics,
with large signal multiplying bandwidths of up to 10 MHz.
The DACs use data readback, allowing the user to read the
contents of the DAC register via the DB pins. On power-up, the
internal register and latches are filled with 0s, and the DAC
outputs are at zero scale.
The applied external reference input voltage (VREF) determines
the full-scale output current. An integrated feedback resistor (RFB)
provides temperature tracking and full-scale voltage output when
combined with an external I-to-V precision amplifier.
The AD5428 is available in a small 20-lead TSSOP package, and
the AD5440/AD5447 DACs are available in small 24-lead TSSOP
packages.
1 U.S. Patent Number 5,689,257.
FUNCTIONAL BLOCK DIAGRAM
04462-001
CONTROL
LOGIC
INPUT
BUFFER
DATA
INPUTS I
OUT
A
DB0
DAC A/B
CS
R/W
DGND
DB7
DB9
DB11
I
OUT
B
AGND
AD5428/AD5440/AD5447
LATCH
LATCH 8-/10-/12-BIT
R-2R DAC A
8-/10-/12-BIT
R-2R DAC B
POWER-ON
RESET
V
DD
V
REF
A
V
REF
B
R
FB
A
R
FB
B
R
R
Figure 1. AD5428/AD5440/AD5447
AD5428/AD5440/AD5447 Data Sheet
Rev. C | Page 2 of 32
TABLE OF CONTENTS
Specifications..................................................................................... 3
Timing Characteristics ................................................................ 5
Absolute Maximum Ratings............................................................ 6
ESD Caution.................................................................................. 6
Pin Configurations and Function Descriptions ........................... 7
Typical Performance Characteristics ........................................... 10
Ter mi nolog y .................................................................................... 15
General Description ....................................................................... 16
DAC Section................................................................................ 16
Circuit Operation ....................................................................... 16
Single-Supply Applications ....................................................... 19
Adding Gain ................................................................................ 19
Divider or Programmable Gain Element................................ 20
Reference Selection .................................................................... 20
Amplifier Selection .................................................................... 20
Parallel Interface......................................................................... 22
Microprocessor Interfacing....................................................... 22
PCB Layout and Power Supply Decoupling ........................... 23
Evaluation Board for the AD5447............................................ 23
Power Supplies for the Evaluation Board................................ 23
Bill of Materials............................................................................... 27
Overview of AD54xx Devices....................................................... 28
Outline Dimensions ....................................................................... 29
Ordering Guide .......................................................................... 29
REVISION HISTORY
8/11—Rev. B to Rev. C
Changes to CS Pin Description, Table 6........................................ 9
3/11—Rev. A to Rev. B
Changes to Evaluation Board For the AD5447 Section ............ 23
Changes to Figure 47 Caption....................................................... 24
Changes to Figure 49...................................................................... 25
Change to U1 Description in Table 12......................................... 27
Change to Ordering Guide............................................................ 29
7/05—Rev. 0 to Rev. A
Changed Pin DAC A/B to DAC A/B................................Universal
Changes to Features List.................................................................. 1
Changes to Specifications................................................................ 3
Changes to Timing Characteristics ................................................ 5
Change to Figure 2 ........................................................................... 5
Change to Absolute Maximum Ratings Section........................... 6
Change to Figure 13, Figure 14, and Figure 18........................... 11
Change to Figure 32 Through Figure 34 ..................................... 14
Changes to General Description Section .................................... 16
Changes to Figure 37...................................................................... 16
Changes to Single-Supply Applications Section......................... 19
Changes to Figure 40 Through Figure 42.................................... 19
Changes to Divider or Programmable Gain Element Section.... 20
Changes to Figure 43...................................................................... 20
Changes to Table 9 Through Table 11 ......................................... 21
Changes to Microprocessor Interfacing Section ........................ 22
Added Figure 44 Through Figure 46 ........................................... 22
Added 8xC51-to-AD5428/AD5440/AD5447
Interface Section........................................................................ 22
Added ADSP-BF5xx-to-AD5428/AD5440/AD5447
Interface Section........................................................................ 22
Changes to Power Supplies for the Evaluation Board Section.... 23
Changes to Table 13 ....................................................................... 28
Updated Outline Dimensions....................................................... 29
Changes to Ordering Guide.......................................................... 29
7/04—Revision 0: Initial Version
Data Sheet AD5428/AD5440/AD5447
Rev. C | Page 3 of 32
SPECIFICATIONS1
VDD = 2.5 V to 5.5 V, VREF = 10 V, IOUT2 = 0 V. Temperature range for Y version: −40°C to +125°C. All specifications TMIN to TMAX, unless
otherwise noted. DC performance is measured with OP177, and ac performance is measured with AD8038, unless otherwise noted.
Table 1.
Parameter Min Typ Max Unit Conditions
STATIC PERFORMANCE
AD5428
Resolution 8 Bits
Relative Accuracy ±0.25 LSB
Differential Nonlinearity ±1 LSB Guaranteed monotonic
AD5440
Resolution 10 Bits
Relative Accuracy ±0.5 LSB
Differential Nonlinearity ±1 LSB Guaranteed monotonic
AD5447
Resolution 12 Bits
Relative Accuracy ±1 LSB
Differential Nonlinearity –1/+2 LSB Guaranteed monotonic
Gain Error ±25 mV
Gain Error Temperature Coefficient ±5 ppm FSR/°C
Output Leakage Current ±5 nA Data = 0x0000, TA = 25°C
±15 nA Data = 0x0000
REFERENCE INPUT
Reference Input Range ±10 V
VREFA, VREFB Input Resistance 8 10 13 kΩ Input resistance TC = –50 ppm/°C
VREFA-to-VREFB Input
Resistance Mismatch
1.6 2.5 % Typ = 25°C, max = 125°C
Input Capacitance
Code 0 3.5 pF
Code 4095 3.5 pF
DIGITAL INPUTS/OUTPUT
Input High Voltage, VIH 1.7 V VDD = 3.6 V to 5.5 V
1.7 V VDD = 2.5 V to 3.6 V
Input Low Voltage, VIL 0.8 V VDD = 2.7 V to 5.5 V
0.7 V VDD = 2.5 V to 2.7 V
Output High Voltage, VOH V
DD − 1 V VDD = 4.5 V to 5.5 V, ISOURCE = 200 µA
V
DD − 0.5 V VDD = 2.5 V to 3.6 V, ISOURCE = 200 µA
Output Low Voltage, VOL 0.4 V VDD = 4.5 V to 5.5 V, ISINK = 200 µA
0.4 V VDD = 2.5 V to 3.6 V, ISINK = 200 µA
Input Leakage Current, IIL 1 µA
Input Capacitance 4 10 pF
DYNAMIC PERFORMANCE
Reference-Multiplying BW 10 MHz VREF = ±3.5 V p-p, DAC loaded all 1s
Output Voltage Settling Time RLOAD = 100 Ω, CLOAD = 15 pF, VREF = 10 V
DAC latch alternately loaded with 0s and 1s
Measured to ±1 mV of FS 80 120 ns
Measured to ±4 mV of FS 35 70 ns
Measured to ±16 mV of FS 30 60 ns
Digital Delay 20 40 ns Interface delay time
10% to 90% Settling Time 15 30 ns Rise and fall times, VREF = 10 V, RLOAD = 100 Ω
Digital-to-Analog Glitch Impulse 3 nV-sec 1 LSB change around major carry, VREF = 0 V
AD5428/AD5440/AD5447 Data Sheet
Rev. C | Page 4 of 32
Parameter Min Typ Max Unit Conditions
Multiplying Feedthrough Error DAC latches loaded with all 0s, VREF = ±3.5 V
70 dB 1 MHz
48 dB 10 MHz
Output Capacitance 12 17 pF DAC latches loaded with all 0s
25 30 pF DAC latches loaded with all 1s
Digital Feedthrough 1 nV-sec Feedthrough to DAC output with CS high and
alternate loading of all 0s and all 1s
Output Noise Spectral Density 25 nV/√Hz @ 1 kHz
Analog THD 81 dB VREF = 3.5 V p-p, all 1s loaded, f = 100 kHz
Digital THD Clock = 10 MHz, VREF = 3.5 V
100 kHz fOUT 61 dB
50 kHz fOUT 66 dB
SFDR Performance (Wide Band) AD5447, 65k codes, VREF = 3.5 V
Clock = 10 MHz
500 kHz fOUT 55 dB
100 kHz fOUT 63 dB
50 kHz fOUT 65 dB
Clock = 25 MHz
500 kHz fOUT 50 dB
100 kHz fOUT 60 dB
50 kHz fOUT 62 dB
SFDR Performance (Narrow Band) AD5447, 65k codes, VREF = 3.5 V
Clock = 10 MHz
500 kHz fOUT 73 dB
100 kHz fOUT 80 dB
50k Hz fOUT 87 dB
Clock = 25 MHz
500 kHz fOUT 70 dB
100 kHz fOUT 75 dB
50 kHz fOUT 80 dB
Intermodulation Distortion AD5447, 65k codes, VREF = 3.5 V
f1 = 40 kHz, f2 = 50 kHz 72 dB Clock = 10 MHz
f1 = 40 kHz, f2 = 50 kHz 65 dB Clock = 25 MHz
POWER REQUIREMENTS
Power Supply Range 2.5 5.5 V
IDD 0.7 µA TA = 25°C, logic inputs = 0 V or VDD
0.5 10 µA TA = −40°C to +125°C, logic inputs = 0 V or VDD
Power Supply Sensitivity 0.001 %/% VDD = ±5%
1 Guaranteed by design, not subject to production test.
Data Sheet AD5428/AD5440/AD5447
Rev. C | Page 5 of 32
TIMING CHARACTERISTICS
All input signals are specified with tr = tf = 1 ns (10% to 90% of VDD) and timed from a voltage level of (VIL + VIH)/2. VDD = 2.5 V to 5.5 V,
VREF = 10 V, IOUT2 = 0 V, temperature range for Y version: −40°C to +125°C. All specifications TMIN to TMAX, unless otherwise noted.
Table 2.
Parameter1 Limit at TMIN, TMAX Unit Conditions/Comments
Write Mode
t1 0 ns min R/W to CS setup time
t2 0 ns min R/W to CS hold time
t3 10 ns min CS low time
t4 10 ns min Address setup time
t5 0 ns min Address hold time
t6 6 ns min Data setup time
t7 0 ns min Data hold time
t8 5 ns min R/W high to CS low
t9 7 ns min CS min high time
Data Readback Mode
t10 0 ns typ Address setup time
t11 0 ns typ Address hold time
t12 5 ns typ Data access time
25 ns max
t13 5 ns typ Bus relinquish time
10 ns max
Update Rate 21.3 MSPS Consists of CS min high time, CS low time, and output
voltage settling time
1 Guaranteed by design and characterization, not subject to production test.
04462-002
DATA VALID DATA VALID
DATA
DACA/DAC
B
CS
R/W
t
1
t
3
t
4
t
10
t
5
t
8
t
7
t
11
t
9
t
2
t
8
t
2
t
12
t
13
Figure 2. Timing Diagram
04462-003
TO OUTPUT
PIN
V
OH (MIN)
+ V
OL (MAX)
200μAI
OH
200μAI
OL
2
C
L
50pF
Figure 3. Load Circuit for Data Output Timing Specifications
AD5428/AD5440/AD5447 Data Sheet
Rev. C | Page 6 of 32
ABSOLUTE MAXIMUM RATINGS
Transient currents of up to 100 mA do not cause SCR latch-up.
TA = 25°C, unless otherwise noted.
Table 3.
Parameter Rating
VDD to GND –0.3 V to +7 V
VREFA, VREFB, RFBA, RFBB to DGND –12 V to +12 V
IOUT1, IOUT2 to DGND –0.3 V to +7 V
Logic Inputs and Output1 –0.3 V to VDD + 0.3 V
Operating Temperature Range
Automotive (Y Version) –40°C to +125°C
Storage Temperature Range –65°C to +150°C
Junction Temperature 150°C
20-lead TSSOP θJA Thermal Impedance 143°C/W
24-lead TSSOP θJA Thermal Impedance 128°C/W
Lead Temperature, Soldering (10 sec) 300°C
IR Reflow, Peak Temperature (<20 sec) 235°C
1 Overvoltages at DBx, CS, and R/W are clamped by internal diodes.
Stresses above those listed in 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 listed in the operational sections of this
specification is not implied. Exposure to absolute maximum
rating conditions for extended periods may affect device
reliability. Only one absolute maximum rating may be applied
at any one time.
ESD CAUTION
Data Sheet AD5428/AD5440/AD5447
Rev. C | Page 7 of 32
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
04462-004
R/W
CS
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
I
OUT
A
R
FB
A
V
REF
A
DB7
DAC A/
B
DGND
AGND
R
FB
B
V
REF
B
V
DD
DB0 (LSB)
DB4
DB5
DB6
DB3
DB2
DB1
I
OUT
B
AD5428
TOP VIEW
(Not to Scale)
Figure 4. Pin Configuration 20-Lead TSSOP (RU-20)
Table 4. AD5428 Pin Function Descriptions
Pin No. Mnemonic Description
1 AGND DAC Ground Pin. This pin should typically be tied to the analog ground of the system, but can be biased to
achieve single-supply operation.
2, 20 IOUTA, IOUTB DAC Current Outputs.
3, 19 RFBA, RFBB DAC Feedback Resistor Pins. These pins establish voltage output for the DAC by connecting to an external
amplifier output.
4, 18 VREFA, VREFB DAC Reference Voltage Input Terminals.
5 DGND Digital Ground Pin.
6 DAC A/B Selects DAC A or DAC B. Low selects DAC A; high selects DAC B.
7 to14 DB7 to DB0 Parallel Data Bits 7 Through 0.
15 CS Chip Select Input. Active low. Used in conjunction with R/W to load parallel data to the input latch or to read
data from the DAC register.
16 R/W Read/Write. When low, used in conjunction with CS to load parallel data. When high, used in conjunction
with CS to read back contents of the DAC register.
17 VDD Positive Power Supply Input. This part can be operated from a supply of 2.5 V to 5.5 V.
AD5428/AD5440/AD5447 Data Sheet
Rev. C | Page 8 of 32
04462-005
R/W
CS
1
2
3
4
5
6
7
8
9
10
20
21
22
23
24
19
18
17
16
15
14
13
12
11
I
OUT
A
R
FB
A
V
REF
A
DB9
DAC A/B
DGND
AGND
R
FB
B
V
REF
B
V
DD
NC
DB8
DB7
DB4
DB5
DB6
NC
DB0 (LSB)
DB3
DB2
DB1
I
OUT
B
AD5440
TOP VIEW
(Not to Scale)
NC = NO CONNECT
Figure 5. Pin Configuration 24-Lead TSSOP (RU-24)
Table 5. AD5440 Pin Function Descriptions
Pin No. Mnemonic Function
1 AGND DAC Ground Pin. This pin should typically be tied to the analog ground of the system, but can be biased to
achieve single-supply operation.
2, 24 IOUTA, IOUTB DAC Current Outputs.
3, 23 RFBA, RFBB DAC Feedback Resistor Pins. Establish voltage output for the DAC by connecting to an external amplifier
output.
4, 22 VREFA, VREFB DAC Reference Voltage Input Terminals.
5 DGND Digital Ground Pin.
6 DAC A/B Selects DAC A or DAC B. Low selects DAC A; high selects DAC B.
7 to16 DB9 to DB0 Parallel Data Bits 9 Through 0.
19 CS Chip Select Input. Active low. Used in conjunction with R/W to load parallel data to the input latch or to read
data from the DAC register.
20 R/W Read/Write. When low, used in conjunction with CS to load parallel data. When high, used in conjunction with
CS to read back contents of the DAC register.
21 VDD Positive Power Supply Input. This part can be operated from a supply of 2.5 V to 5.5 V.
Data Sheet AD5428/AD5440/AD5447
Rev. C | Page 9 of 32
04462-006
R/W
CS
1
2
3
4
5
6
7
8
9
10
20
21
22
23
24
19
18
17
16
15
14
13
12
11
I
OUT
A
R
FB
A
V
REF
A
DB11
DAC A/B
DGND
AGND
R
FB
B
V
REF
B
V
DD
DB0 (LSB)
DB10
DB9
DB6
DB7
DB8
DB1
DB2
DB5
DB4
DB3
I
OUT
B
AD5447
TOP VIEW
(Not to Scale)
Figure 6. Pin Configuration 24-Lead TSSOP (RU-24)
Table 6. AD5447 Pin Function Descriptions
Pin No. Mnemonic Description
1 AGND DAC Ground Pin. This pin should typically be tied to the analog ground of the system, but can be biased to
achieve single-supply operation.
2, 24 IOUTA, IOUTB DAC Current Outputs.
3, 23 RFBA, RFBB DAC Feedback Resistor Pins. Establish voltage output for the DAC by connecting to an external amplifier
output.
4, 22 VREFA, VREFB DAC Reference Voltage Input Terminals.
5 DGND Digital Ground Pin.
6 DAC A/B Selects DAC A or DAC B. Low selects DAC A; high selects DAC B.
7 to 18 DB11 to DB0 Parallel Data Bits 11 Through 0.
19 CS Chip Select Input. Active low. Used in conjunction with R/W to load parallel data to the input latch or to read
data from the DAC register.
20 R/W Read/Write. When low, used in conjunction with CS to load parallel data. When high, used in conjunction with
CS to read back the contents of the DAC register. When CS and R/W are held low, the latches are transparent.
Any changes on the data lines are reflected in the relevant DAC output.
21 VDD Positive Power Supply Input. This part can be operated from a supply of 2.5 V to 5.5 V.
AD5428/AD5440/AD5447 Data Sheet
Rev. C | Page 10 of 32
TYPICAL PERFORMANCE CHARACTERISTICS
–0.20
–0.15
–0.10
–0.05
0
0.05
INL (LSB)
0.10
0.15
0.20
04462-007
0 50 100 150 200 250
CODE
T
A
= 25°C
V
REF
= 10V
V
DD
= 5V
Figure 7. INL vs. Code (8-Bit DAC)
–0.5
–0.4
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0.4
0.5
INL (LSB)
04462-008
0 200 400 600 800 1000
CODE
TA = 25°C
VREF = 10V
VDD = 5V
Figure 8. INL vs. Code (10-Bit DAC)
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
1.0
INL (LSB)
20001500500 10000 2500 3000 3500 4000
CODE
04462-009
T
A
= 25°C
V
REF
= 10V
V
DD
= 5V
Figure 9. INL vs. Code (12-Bit DAC)
–0.20
–0.15
–0.10
–0.05
0
0.05
DNL (LSB)
0.10
0.15
0.20
04462-010
0 50 100 150 200 250
CODE
T
A
= 25°C
V
REF
= 10V
V
DD
= 5V
Figure 10. DNL vs. Code (8-Bit DAC)
–0.5
–0.4
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0.4
0.5
DNL (LSB)
04462-011
0 200 400 600 800 1000
CODE
T
A
= 25°C
V
REF
= 10V
V
DD
= 5V
Figure 11. DNL vs. Code (10-Bit DAC)
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
1.0
DNL (LSB)
20001500500 10000 2500 3000 3500 4000
CODE
04462-012
T
A
= 25°C
V
REF
= 10V
V
DD
= 5V
Figure 12. DNL vs. Code (12-Bit DAC)
Data Sheet AD5428/AD5440/AD5447
Rev. C | Page 11 of 32
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
INL (LSB)
65342 78910
REFERENCE VOLTAGE
04462-013
MAX INL
MIN INL
T
A
= 25°C
V
DD
= 5V
Figure 13. INL vs. Reference Voltage
–0.70
–0.65
–0.60
–0.55
–0.50
–0.45
–0.40
DNL (LSB)
65342789
REFERENCE VOLTAGE
04462-014
10
MIN DNL
T
A
= 25°C
V
DD
= 5V
Figure 14. DNL vs. Reference Voltage
–5
–4
–3
–2
–1
0
1
2
3
4
5
ERROR (mV)
–60 –40 –20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
04462-015
V
DD
= 5V
V
DD
= 2.5V
V
REF
= 10V
Figure 15. Gain Error vs. Temperature
INPUT VOLTAGE (V)
CURRENT (mA)
8
5
05.0
7
6
3
1
4
2
4.54.03.53.02.52.01.5
1.00.50
V
DD
= 5V
V
DD
= 3V
V
DD
= 2.5V
04462-022
T
A
= 25°C
Figure 16. Supply Current vs. Logic Input Voltage
0
0.2
0.4
0.6
0.8
1.0
I
OUT
1 LEAKAGE (nA)
1.2
1.4
1.6
4020–20 0–40 60 80 100 120
TEMPERATURE (°C)
04462-023
I
OUT
1 V
DD
= 5V
I
OUT
1 V
DD
= 3V
Figure 17. IOUT1 Leakage Current vs. Temperature
0
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
CURRENT (μA)
–60 –40 –20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
04462-024
V
DD
= 5V
V
DD
= 2.5V
ALL 0s
ALL 1s
ALL 0sALL 1s
Figure 18. Supply Current vs. Temperature
AD5428/AD5440/AD5447 Data Sheet
Rev. C | Page 12 of 32
0
2
4
6
8
10
12
14
I
DD
(mA)
10k1k10 1001 100k 1M 10M 100M
FREQUENCY (Hz)
04462-025
T
A
= 25°C
LOADING ZS TO FS
V
DD
= 5V
V
DD
= 3V
V
DD
= 2.5V
Figure 19. Supply Current vs. Update Rate
–102
–66
–54
–42
–30
–18
–6
6
1 100 1k 10k 100k 1M 10M 100M
FREQUENCY (Hz)
GAIN (dB)
T
A
= 25°C
LOADING
ZS TO FS
0
–60
–48
–36
–24
–12
–84
–72
–78
–90
–96
T
A
= 25°C
V
DD
= 5V
V
REF
= ±3.5V
C
COMP
=1.8pF
AMP = AD8038
ALL ON
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
ALL OFF
04462-026
10
Figure 20. Reference Multiplying Bandwidth vs. Frequency and Code
–0.8
–0.6
–0.4
–0.2
0
0.2
GAIN (dB)
10k1k10 1001 100k 1M 10M 100M
FREQUENCY (Hz)
04462-027
T
A
= 25°C
V
DD
= 5V
V
REF
=
±
3.5V
C
COMP
= 1.8pF
AMP = AD8038
Figure 21. Reference Multiplying Bandwidth—All 1s Loaded
–9
–6
–3
0
3
10k 100k 1M 10M 100M
FREQUENCY (Hz)
T
A
= 25°C
V
DD
= 5V
GAIN (dB)
04462-028
V
REF
= ±2V, AD8038 C
C
1.47pF
V
REF
= ±2V, AD8038 C
C
1pF
V
REF
= ±0.15V, AD8038 C
C
1pF
V
REF
= ±0.15V, AD8038 C
C
1.47pF
V
REF
= ±3.51V, AD8038 C
C
1.8pF
Figure 22. Reference Multiplying Bandwidth vs. Frequency and
Compensation Capacitor
–0.010
–0.005
0.005
0.025
0.035
0.045
0.015
0
0.020
0.030
0.040
0.010
OUTPUT VOLTAGE (V)
0 20 40 60 80 100 120 140 160 180 200
TIME (ns)
04462-041
T
A
= 25°C
V
REF
= 0V
AMP = AD8038
C
COMP
= 1.8pF
0x7FF TO 0x800
0x800 TO 0x7FF
V
DD
= 5V
V
DD
= 3V
V
DD
= 3V
V
DD
= 5V
Figure 23. Midscale Transition, VREF = 0 V
OUTPUT VOLTAGE (V)
0 20 40 60 80 100 120 140 160 180 200
TIME (ns)
04462-042
–1.77
–1.76
–1.75
–1.74
–1.73
–1.72
–1.71
–1.70
–1.69
–1.68
0x7FF TO 0x800
0x800 TO 0x7FF
V
DD
= 5V
V
DD
= 3V
V
DD
= 3V
V
DD
= 5V
T
A
= 25°C
V
REF
= 3.5V
AMP = AD8038
C
COMP
= 1.8pF
Figure 24. Midscale Transition, VREF = 3.5 V
Data Sheet AD5428/AD5440/AD5447
Rev. C | Page 13 of 32
–120
–100
–80
–60
0
20
1 100 1k 10k 100k 1M 10M
FREQUENCY (Hz)
–40
–20
T
A
= 25°C
V
DD
= 3V
AMP = AD8038
FULL SCALE
ZERO SCALE
PSRR (dB)
04462-043
10
Figure 25. Power Supply Rejection Ratio vs. Frequency
–90
–85
–80
–75
–70
–65
–60
THD + N (dB)
100 1k1 10 10k 100k 1M
FREQUENCY (Hz)
04462-044
T
A
= 25°C
V
DD
= 3V
V
REF
= 3.5V p-p
Figure 26. THD + Noise vs. Frequency
0
20
40
60
80
100
SFDR (dB)
0 20 40 60 80 100 120 140 160 180 200
f
OUT
(kHz)
04462-045
T
A
= 25°C
V
REF
= 3.5V
AMP = AD8038
MCLK = 1MHz
MCLK = 200kHz
MCLK = 0.5MHz
Figure 27. Wideband SFDR vs. fOUT Frequency
0
10
20
30
40
50
60
70
80
90
SFDR (dB)
0 100 200 300 400 500 600 700 800 900 1000
f
OUT
(kHz)
04462-046
MCLK = 5MHz
MCLK = 10MHz
MCLK = 25MHz
T
A
= 25°C
V
REF
= 3.5V
AMP = AD8038
Figure 28. Wideband SFDR vs. fOUT Frequency
04462-047
–90
–70
–50
–30
–10
SFDR (dB)
0
FREQUENCY (MHz)
–80
–60
–40
–20
0
T
A
= 25°C
V
DD
= 5V
AMP = AD8038
65k CODES
2 4 6 8 10 12
Figure 29. Wideband SFDR, fOUT = 100 kHz, Clock = 25 MHz
04462048
–100
–70
–50
–30
–10
SFDR (dB)
0
FREQUENCY (MHz)
–80
–60
–40
–20
0
T
A
= 25°C
V
DD
= 5V
AMP = AD8038
65k CODES
0.5 1.5 3.0 3.5 4.01.0 2.0 2.5 4.5 5.0
–90
Figure 30. Wideband SFDR, fOUT = 500 kHz, Clock = 10 MHz
AD5428/AD5440/AD5447 Data Sheet
Rev. C | Page 14 of 32
04462-052
FREQUENCY (kHz)
–100
–70
–50
–30
–10
IMD (dB)
70 12075 80 85 115
–80
–60
–40
–20
0
–90
90 100 105 110
T
A
= 25°C
V
DD
= 3V
AMP = AD8038
65k CODES
95
04462-049
–90
–70
–50
–30
–10
SFDR (dB)
0
FREQUENCY (MHz)
–80
–60
–40
–20
0
0.5 1.5 3.0 3.5 4.01.0 2.0 2.5 4.5 5.0
T
A
= 25°C
V
DD
= 5V
AMP = AD8038
65k CODES
Figure 31. Wideband SFDR, fOUT = 50 kHz, Clock = 10 MHz Figure 34. Narrow-Band IMD, fOUT = 90 kHz, 100 kHz, Clock = 10 MHz
04462-050
FREQUENCY (kHz)
T
A
= 25°C
V
DD
= 3V
AMP = AD8038
65k CODES
–100
–70
–50
–30
–10
SFDR (dB)
250 750300 350 400 650 700
–80
–60
–40
–20
0
–90
450 500 550 600
04462-53
–100
–40
–20
IMD (dB)
–50
–30
–10
–90
–60
–70
–80
0 400
FREQUENCY (kHz)
50 300 350100 150 200 250
0
T
A
= 25°C
V
DD
= 5V
AMP = AD8038
65k CODES
Figure 32. Narrow-Band SFDR, fOUT = 500 kHz, Clock = 25 MHz Figure 35. Wideband IMD, fOUT = 90 kHz, 100 kHz, Clock = 25 MHz
100 1k 10k 100k
FREQUENCY (Hz)
T
A
= 25°C
AMP = AD8038
FULL SCALE LOADED TO DAC
ZERO SCALE LOADED TO DAC
04462-054
0
50
100
150
200
250
300
OUTPUT NOISE (nV/ Hz)
MIDSCALE LOADED TO DAC
04462-051
–120
–60
–20
SFDR (dB)
50 150
FREQUENCY (kHz)
60 70 80 130 140
–80
–40
0
20
–100
90 100 110 120
T
A
= 25°C
V
DD
= 3V
AMP = AD8038
65k CODES
Figure 36. Output Noise Spectral Density
Figure 33. Narrow-Band SFDR, fOUT = 100 kHz, Clock = 25 MHz
Data Sheet AD5428/AD5440/AD5447
Rev. C | Page 15 of 32
TERMINOLOGY
Relative Accuracy (Endpoint Nonlinearity)
A measure of the maximum deviation from a straight line
passing through the endpoints of the DAC transfer function. It
is measured after adjusting for zero and full scale and is
typically expressed in LSBs or as a percentage of the full-scale
reading.
Differential Nonlinearity
The difference in the measured change and the ideal 1 LSB
change between two adjacent codes. A specified differential
nonlinearity of −1 LSB maximum over the operating
temperature range ensures monotonicity.
Gain Error (Full-Scale Error)
A measure of the output error between an ideal DAC and the
actual device output. For these DACs, ideal maximum output is
VREF – 1 LSB. The gain error of the DACs is adjustable to zero
with an external resistance.
Output Leakage Current
The current that flows into the DAC ladder switches when they
are turned off. For the IOUT1 terminal, it can be measured by
loading all 0s to the DAC and measuring the IOUT1 current.
Minimum current flows into the IOUT2 line when the DAC is
loaded with all 1s.
Output Capacitance
Capacitance from IOUT1 or IOUT2 to AGND.
Output Current Settling Time
The amount of time for the output to settle to a specified level
for a full-scale input change. For these devices, it is specified
with a 100 Ω resistor to ground.
Digital-to-Analog Glitch Impulse
The amount of charge injected from the digital inputs to the
analog output when the inputs change state. This is normally
specified as the area of the glitch in either pA-sec or nV-sec,
depending on whether the glitch is measured as a current or
voltage signal.
Digital Feedthrough
When the device is not selected, high frequency logic activity
on the device’s digital inputs is capacitively coupled through the
device and produces noise on the IOUT pins and, subsequently,
on the following circuitry. This noise is digital feedthrough.
Multiplying Feedthrough Error
The error due to capacitive feedthrough from the DAC
reference input to the DAC IOUT1 terminal when all 0s are
loaded to the DAC.
Total Harmonic Distortion (THD)
The DAC is driven by an ac reference. The ratio of the rms sum
of the harmonics of the DAC output to the fundamental value is
the THD. Usually only the lower-order harmonics are included,
such as second to fifth harmonics.
1
54
32
V
VVVV
THD
2222
log20 +++
=
Digital Intermodulation Distortion
Second-order intermodulation distortion (IMD) measurements
are the relative magnitude of the fa and fb tones digitally generated
by the DAC and the second-order products at 2fa − fb and
2fb − fa.
Spurious-Free Dynamic Range (SFDR)
SFDR is the usable dynamic range of a DAC before spurious
noise interferes or distorts the fundamental signal. SFDR is the
measure of difference in amplitude between the fundamental
and the largest harmonic or nonharmonic spur from dc to full
Nyquist bandwidth (half the DAC sampling rate, or fs/2).
Narrow-band SFDR is a measure of SFDR over an arbitrary
window size, in this case 50%, of the fundamental. Digital SFDR
is a measure of the usable dynamic range of the DAC when the
signal is a digitally generated sine wave.
AD5428/AD5440/AD5447 Data Sheet
Rev. C | Page 16 of 32
GENERAL DESCRIPTION
DAC SECTION
The AD5428/AD5440/AD5447 are CMOS 8-, 10-, and 12-bit,
dual-channel, current output DACs consisting of a standard
inverting R-2R ladder configuration. Figure 37 shows a simplified
diagram for a single channel of the 8-bit AD5428. The feedback
resistor RFBA has a value of R. The value of R is typically 10 kΩ
(with a minimum of 8 kΩ and a maximum of 12 kΩ). If IOUT1
and AGND are kept at the same potential, a constant current
flows into each ladder leg, regardless of digital input code.
Therefore, the input resistance presented at VREFA is always
constant and nominally of value R. The DAC output (IOUT) is
code-dependent, producing various resistances and
capacitances. When choosing an external amplifier, take into
account the variation in impedance generated by the DAC on
the amplifier’s inverting input node.
04462-029
V
REF
DAC DATA LATCHES
AND DRIVERS
R
FB
A
I
OUT
A
AGND
RR R
R
2R 2R 2R 2R 2R
S1 S2 S3 S8
Figure 37. Simplified Ladder
Access is provided to the VREF, RFB, and IOUT terminals of DAC A
and DAC B, making the devices extremely versatile and
allowing them to be configured in several operating modes,
such as unipolar output mode, 4-quadrant multiplication
bipolar mode, or single-supply mode. Note that a matching
switch is used in series with the internal RFBA feedback resistor.
If users attempt to measure RFBA, power must be applied to VDD
to achieve continuity.
CIRCUIT OPERATION
Unipolar Mode
Using a single op amp, these devices can easily be configured to
provide 2-quadrant multiplying operation or a unipolar output
voltage swing, as shown in Figure 38. When an output amplifier
is connected in unipolar mode, the output voltage is given by
n
REF
OUT DVV 2/×−=
where:
D is the fractional representation of the digital word loaded to
the DAC.
D = 0 to 255 (8-bit AD5428)
= 0 to 1023 (10-bit AD5440)
= 0 to 4095 (12-bit AD5447)
n is the resolution of the DAC.
Note that the output voltage polarity is opposite to the VREF
polarity for dc reference voltages. These DACs are designed to
operate with either negative or positive reference voltages. The
VDD power pin is only used by the internal digital logic to drive
the on and off states of the DAC switches.
These DACs are also designed to accommodate ac reference
input signals in the range of –10 V to +10 V.
With a fixed 10 V reference, the circuit in Figure 38 gives a
unipolar 0 V to –10 V output voltage swing. When VIN is an ac
signal, the circuit performs 2-quadrant multiplication.
Table 7 shows the relationship between digital code and the
expected output voltage for unipolar operation using the 8-bit
AD5428.
Table 7. Unipolar Code
Digital Input Analog Output (V)
1111 1111 –VREF (255/256)
1000 0000 –VREF(128/256) = –VREF/2
0000 0001 –VREF (1/256)
0000 0000 –VREF (0/256) = 0
Data Sheet AD5428/AD5440/AD5447
Rev. C | Page 17 of 32
04462-030
CONTROL
LOGIC
INPUT
BUFFER
DATA
INPUTS
I
OUT
A
DB0
DAC A/B
CS
R/W
DGND
DB7
DB9
DB11
I
OUT
B
AGND
AD5428/AD5440/AD5447
LATCH
LATCH
AGND
8-/10-/12-BIT
R-2R DAC A
8-/10-/12-BIT
R-2R DAC B
POWER-ON
RESET
V
DD
V
REF
A
V
IN
A
(±10V)
V
REF
B
R
FB
A
R
FB
B
R
R
V
OUT
A
R1
1
V
IN
B
(±10V)
R3
1
R2
1
C1
2
AGND
V
OUT
B
R4
1
C2
2
1
R1, R2 AND R3, R4 USED ONLY IF GAIN ADJUSTMENT IS REQUIRED.
2
C1, C2 PHASE COMPENSATION (1pF TO 2pF) IS REQUIRED WHEN USING
HIGH SPEED AMPLIFIERS TO PREVENT RINGING OR OSCILLATION.
Figure 38. Unipolar Operation
AD5428/AD5440/AD5447 Data Sheet
Rev. C | Page 18 of 32
Bipolar Operation
In some applications, it may be necessary to generate full 4-quad-
rant multiplying operation or a bipolar output swing. This can
easily be accomplished by using another external amplifier and
some external resistors, as shown in Figure 39. In this circuit, the
second amplifier, A2, provides a gain of 2. Biasing the external
amplifier with an offset from the reference voltage results in full
4-quadrant multiplying operation. The transfer function of this
circuit shows that both negative and positive output voltages are
created as the input data (D) is incremented from Code 0 (VOUT =
−VREF) to midscale (VOUT = 0 V) to full scale (VOUT = +VREF).
When connected in bipolar mode, the output voltage is given by
()
REF
n
REF
OUT VDVV −×= −1
2/
where:
D is the fractional representation of the digital word loaded to
the DAC.
D = 0 to 255 (AD5428)
= 0 to 1023 (AD5440)
= 0 to 4095 (AD5447)
n is the number of bits.
When VIN is an ac signal, the circuit performs 4-quadrant
multiplication. Table 8 shows the relationship between digital
code and the expected output voltage for bipolar operation
using the 8-bit AD5428.
Table 8. Bipolar Code
Digital Input Analog Output (V)
1111 1111 +VREF (127/128)
1000 0000 0
0000 0001 –VREF (127/128)
0000 0000 –VREF (128/128)
Stability
In the I-to-V configuration, the IOUT of the DAC and the inverting
node of the op amp must be connected as close as possible, and
proper PCB layout techniques must be used. Because every code
change corresponds to a step function, gain peaking may occur
if the op amp has limited gain bandwidth product (GBP) and
there is excessive parasitic capacitance at the inverting node.
This parasitic capacitance introduces a pole into the open-loop
response, which can cause ringing or instability in the closed-
loop applications circuit.
An optional compensation capacitor, C1, can be added in parallel
with RFBA for stability, as shown in Figure 38 and Figure 39. Too
small a value of C1 can produce ringing at the output, whereas
too large a value can adversely affect the settling time. C1 should
be found empirically, but 1 pF to 2 pF is generally adequate for
the compensation.
04462-031
CONTROL
LOGIC
INPUT
BUFFER
DATA
INPUTS
I
OUT
A
DB0
DAC A/B
CS
R/W
DGND
DB7
DB9
DB11
I
OUT
B
AGND
AD5428/AD5440/AD5447
LATCH
LATCH
AGND
8-/10-/12-BIT
R-2R DAC A
8-/10-/12-BIT
R-2R DAC B
POWER-ON
RESET
V
DD
V
REF
A
V
IN
A
(±10V)
V
REF
B
R
FB
A
R
FB
B
R
RR2
1
V
OUT
A
R1
1
V
IN
B
(±10V)
R3
1
R6
2
20kΩ
R5
20kΩ
R8
20kΩ
R11
5kΩ
R12
5kΩ
R7
2
10kΩ
R9
2
10kΩ
R10
2
20kΩ
C1
3
AGND
AGND
AGND
V
OUT
B
R4
1
C2
3
A1
A3
A2
A4
1
R1, R2 AND R3, R4 USED ONLY IF GAIN ADJUSTMENT IS REQUIRED. ADJUST R1 FOR V
OUT
A = 0V WITH CODE 10000000 IN DAC A LATCH.
ADJUST R3 FOR
V
OUT
B = 0V WITH CODE 10000000 IN DAC B LATCH.
2
MATCHING AND TRACKING IS ESSENTIAL FOR RESISTOR PAIRS R6, R7 AND R9, R10.
3
C1, C2 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRED IF A1/A3 IS A HIGH SPEED AMPLIFIER.
Figure 39. Bipolar Operation (4-Quadrant Multiplication)
Data Sheet AD5428/AD5440/AD5447
Rev. C | Page 19 of 32
SINGLE-SUPPLY APPLICATIONS
Voltage-Switching Mode
Figure 40 shows the DACs operating in voltage-switching
mode. The reference voltage, VIN, is applied to the IOUTA pin,
and the output voltage is available at the VREFA terminal. In this
configuration, a positive reference voltage results in a positive
output voltage, making single-supply operation possible. The
output from the DAC is voltage at constant impedance (the
DAC ladder resistance). Therefore, an op amp is necessary to
buffer the output voltage. The reference input no longer sees
constant input impedance, but one that varies with code.
Therefore, the voltage input should be driven from a low
impedance source.
Note that VIN is limited to low voltages because the switches in
the DAC ladder no longer have the same source-drain drive
voltage. As a result, their on resistance differs and degrades the
integral linearity of the DAC. Also, VIN must not go negative by
more than 0.3 V, or an internal diode turns on, causing the
device to exceed the maximum ratings. In this type of
application, the full range of multiplying capability of the DAC
is lost.
04462-033
NOTES
1. ADDITIONAL PINS OMITTED FOR CLARITY.
2. C1 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRED
IF A1 IS A HIGH SPEED AMPLIFIER.
V
DD
V
IN
V
REF
A
V
DD
R
FB
A
GND
V
OUT
I
OUT
A
AGND
R1 R2
Figure 40. Single-Supply Voltage-Switching Mode
Positive Output Voltage
The output voltage polarity is opposite to the VREF polarity for
dc reference voltages. To achieve a positive voltage output, an
applied negative reference to the input of the DAC is preferred
over the output inversion through an inverting amplifier
because of the resistor’s tolerance errors. To generate a negative
reference, the reference can be level-shifted by an op amp such
that the VOUT and GND pins of the reference become the virtual
ground and –2.5 V, respectively, as shown in Figure 41.
04462-034
NOTES
1. ADDITIONAL PINS OMITTED FOR CLARITY
.
2
. C1 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRE
D
IF A1 IS A HIGH SPEED AMPLIFIER.
V
DD
= 5V
V
DD
C1
V
IN
V
REF
A
R
FB
A
8-/10-/12-BIT
DAC
ADR03
GND
GND
V
OUT
V
OUT
=
0V to 2.5V
I
OUT
A
AGND
+5V
–5V
–2.5V
Figure 41. Positive Voltage Output with Minimum Components
ADDING GAIN
In applications where the output voltage must be greater than
VIN, gain can be added with an additional external amplifier, or
it can be achieved in a single stage. Consider the effect of temper-
ature coefficients of the thin film resistors of the DAC. Simply
placing a resistor in series with the RFB resistor causes mismatches
in the temperature coefficients, resulting in larger gain temper-
ature coefficient errors. Instead, the circuit in Figure 42 shows
the recommended method for increasing the gain of the circuit.
R1, R2, and R3 should have similar temperature coefficients,
but they need not match the temperature coefficients of the
DAC. This approach is recommended in circuits where gains of
greater than 1 are required.
04462-035
NOTES
1. ADDITIONAL PINS OMITTED FOR CLARITY.
2. C1 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRED
IF A1 IS A HIGH SPEED AMPLIFIER.
V
DD
V
DD
C1
V
IN
V
REF
A
R
FB
A
R1
R3
R2
8-/10-/12-BIT
DAC
GND
V
OUT
I
OUT
A
AGND
R2 + R3
R2
GAIN =
R
1
=R2R3
R2
+
R3
Figure 42. Increasing Gain of Current Output DAC