Dual Current Output, Parallel Input, 16-/14-Bit

Multiplying DACs with 4-Quadrant Resistors

AD5547/AD5557

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700

www.analog.com

Fax: 781.326.8703

FEATURES

Dual channel
16-bit resolution: AD5547
14-bit resolution: AD5557
2- or 4-quadrant, 4 MHz BW multiplying DAC
±1 LSB DNL
±1 LSB INL for AD5557, ±2 LSB INL for AD5547
Operating supply voltage: 2.7 V to 5.5 V
Low noise: 12 nV/Hz
Low power: I

= 10 µA max

0.5 µs settling time
Built-in R

facilitates current-to-voltage conversion

Built-in 4-quadrant resistors allow 0 V to 10 V, 0 V to +10 V,

or ±10 V outputs

2 mA full-scale current ± 20%, with V

REF

= 10 V

Extended automotive operating temperature range:

40°C to +125°C

Selectable zero-scale/midscale power-on presets
Compact TSSOP-38 package

APPLICATIONS

Automatic test equipment
Instrumentation
Digitally controlled calibration
Digital waveform generation

GENERAL DESCRIPTION

The AD5547/AD5557 are dual precision, 16-/14-bit,
multiplying, low power, current-output, parallel input, digital-
to-analog converters. They are designed to operate from single
+5 V supply with ±10 V multiplying references for 4-quadrant
outputs with up to 4 MHz bandwidth.

FUNCTIONAL BLOCK DIAGRAM

DAC A

D0..D15

D0..D13

DAC A
DAC B

ADDR
DECODE

INPUT

REGISTER

DAC A

REGISTER

DAC B

REGISTER

POWER

RESET

COMB

COMA

OFSA

REFA

OFSB

04452-0-013

FBA

AGNDA

AGNDB

REFB

OUTA

FBB

OUTB

D0D15

(AD5547)

D0D13

(AD5557)

A0, A1

MSB

LDAC

DGND

INPUT

REGISTER

DAC B

AD5547/AD5557

Figure 1.

The built-in 4-quadrant resistors facilitate resistance matching
and temperature tracking, which minimize the numbers of
components needed for multiquadrant applications. In addition,
the feedback resistor (R

) simplifies the I-V conversion with an

external buffer.

The AD5547/AD5557 are available in a compact TSSOP-38
package and operate at the extended automotive temperature
range of 40°C to +125°C.

VREF

VREF TO +VREF

04452-0-002

16/14 DATA

COMA

OFSA

FBA

RFB

ROFS

16-/14-BIT

DAC A

MSB A0, A1

POWER-ON

RESET

AD5547/AD5557

IOUTA

AGNDA

(ONE CHANNEL SHOWN ONLY)

VOUTA

REFA

MSB

A0, A1

LDAC

Figure 2. 16/14-Bit 4-Quadrant Multiplying DAC with Minimum of External Components (Only One Channel Shown)

AD5547/AD5557

Rev. 0 | Page 2 of 20

TABLE OF CONTENTS

Specifications..................................................................................... 3

Absolute Maximum Ratings............................................................ 5

ESD Caution.................................................................................. 5

Pin Configurations and Function Descriptions ........................... 6

Typical Performance Characteristics ............................................. 9

Circuit Operation ........................................................................... 12

D/A Converter Section .............................................................. 12

Digital Section............................................................................. 13

PCB Layout, Power Supply Bypassing, and Ground
Connections ................................................................................ 13

Applications..................................................................................... 14

Unipolar Mode ........................................................................... 14

Bipolar Mode .............................................................................. 16

Outline Dimensions ....................................................................... 19

Ordering Guide .......................................................................... 19

REVISION HISTORY

Revision 0: Initial Version

AD5547/AD5557

Rev. 0 | Page 3 of 20

SPECIFICATIONS

= 2.7 V to 5.5 V, I

OUT

= Virtual GND, GND = 0 V, V

REF

= 10 V to +10 V, T

= 40°C to +125°C, unless otherwise noted.

Table 1. Electrical Characteristics

Parameter Symbol

Conditions

Min

Typ

Max

Unit

STATIC PERFORMANCE

Resolution

AD5547, 1 LSB = V

REF

= 153 µV at V

REF

= 10 V

Bits

AD5557, 1 LSB = V

REF

= 610 µV at V

REF

= 10 V

Bits

Relative Accuracy

INL

Grade: AD5557C

±1

LSB

Grade:

AD5547B

±2

LSB

Differential Nonlinearity

DNL

Monotonic

±1

LSB

Output Leakage Current

OUT

Data = zero scale, T

= 25°C

Data = zero scale, T

= T

maximum

Full-Scale Gain Error

FSE

Data = full scale

±1

±4

Bipolar Mode Gain Error

Data = full scale

±1

±4

Bipolar Mode Zero-Scale Error

ZSE

Data = full scale

±1

±3

Full-Scale Tempco

TCV

ppm/°C

REFERENCE INPUT

REF

Range

REF

+18

REF Input Resistance

REF

R1 and R2 Resistance

R1 and R2

R1-to-R2 Mismatch

(R1 to R2)

±0.5

±1.5

Feedback and Offset Resistance

, R

OFS

8 10

12 k

Input Capacitance

REF

ANALOG OUTPUT

Output Current

OUT

Data = full scale

Output Capacitance

OUT

Code

dependent

200

LOGIC INPUT AND OUTPUT

Logic Input Low Voltage

= 5 V

0.8

= 3 V

0.4

Logic Input High Voltage

= 5 V

2.4

= 3 V

2.1

Input Leakage Current

µA

Input Capacitance

INTERFACE TIMING

2, 3

Data to WR Setup Time

= 5 V

= 3 V

Data to WR Hold Time

= 5 V

= 3 V

WR Pulse Width

= 5 V

= 3 V

LDAC Pulse Width

LDAC

= 5 V

= 3 V

RS Pulse Width

= 5 V

= 3 V

WR to LDAC Delay Time

LWD

= 5 V

= 3 V

SUPPLY CHARACTERISTICS

Power Supply Range

DD RANGE

2.7

5.5 V

Positive Supply Current

Logic inputs = 0 V

µA

Power Dissipation

DISS

Logic inputs = 0 V

0.055

Power Supply Sensitivity

= ±5%

0.003

%/%

AD5547/AD5557

Rev. 0 | Page 4 of 20

Parameter Symbol

Conditions

Min

Typ

Max

Unit

AC CHARACTERISTICS

Output Voltage Settling Time

To ±0.1% of full scale, data cycles from zero scale
to full scale to zero scale

0.5

µs

Reference Multiplying BW

REF

= 5 V p-p, data = full scale

MHz

DAC Glitch Impulse

REF

= 0 V, midscale to midscale 1

nV-s

Multiplying Feedthrough Error

OUT

REF

= 100 mV rms, f = 10 kHz

Digital Feedthrough

WR = 1, LDAC toggles at 1 MHz

7 nV-s

Total Harmonic Distortion

THD

REF

= 5 V p-p, data = full scale, f = 1 kHz

Output Noise Density

f = 1 kHz, BW = 1 Hz

nV/Hz

Analog Crosstalk

Signal input at Channel A and measure the output
at Channel B, f = 1 kHz

All static performance tests (except I

OUT

) are performed in a closed-loop system using an external precision OP97 I-V converter amplifier. The device R

terminal is tied

to the amplifier output. The OP97's +IN pin is grounded, and the DAC's I

OUT

is tied to the OP97's IN pin. Typical values represent average readings measured at 25°C.

Guaranteed by design; not subject to production testing.

All input control signals are specified with t

= t

= 2.5 ns (10% to 90% of 3 V), and are timed from a voltage level of 1.5 V.

All ac characteristic tests are performed in a closed-loop system using an AD841 I-V converter amplifier.

03810-0-005

LWD

LDAC

DATA

LDAC

Figure 3. AD5547/AD5557 Timing Diagram

AD5547/AD5557

Rev. 0 | Page 5 of 20

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

to GND

0.3 V, +8 V

, R

OFS

, R1, R

COM

, and VREF to GND

18 V, 18 V

Logic Inputs to GND

0.3 V, +8 V

V(I

OUT

) to GND

0.3 V, V

+ 0.3 V

Input Current to Any Pin except Supplies

±50 mA

Thermal Resistance (

)

Maximum Junction Temperature (T

MAX

) 150°C

Operating Temperature Range

40°C to +125°C

Storage Temperature Range

65°C to +150°C

Lead Temperature

Vapor Phase, 60 s

215°C

Infrared, 15 s

220°C

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 listed in the operational sections
of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.

Package power dissipation = (T

J MAX

ESD CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.

AD5547/AD5557

Rev. 0 | Page 6 of 20

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

AD5547

TOP VIEW

(Not to Scale)

OFSA

FBA

REFA

OUTA

AGNDA

DGND

AGNDA

OUTB 12

REFB 13

COMB 14

1B 15

FBB 16

OFSB 17

D10

VDD

D11

D12

D13

D14

D15

MSB

LDAC

COMA

04452-0-003

OFSA

FBA

REFA

OUTA

AGNDA

DGND

AGNDB

OUTB 12

REFB 13

COMB 14

1B 15

FBB 16

OFSB 17

COMA

NC = NO CONNECT

VDD

D10

D11

D12

D13

MSB

LDAC

04452-0-004

AD5557

TOP VIEW

(Not to Scale)

Figure 4. AD5547 TSSOP-38 Pin Configuration

Figure 5. AD5557 TSSOP-38 Pin Configuration

Table 3. AD5547 Pin Function Descriptions

Pin No.

Mnemonic

Function

1, 2, 24
28, 3038

D0D15

Digital Input Data Bits D0 to D15. Signal level must be V

+ 0.3 V.

3 R

OFSA

Bipolar Offset Resistor A. Accepts up to ±18 V. In 2-quadrant mode, R

OFSA

ties to R

FBA

. In 4-quadrant mode, R

OFSA

ties to R

and the external reference.

4 R

FBA

Internal Matching Feedback Resistor A. Connects to the external op amp for I-V conversion.

5 R

4-Quandrant Resistor. In 2-quadrant mode, R

shorts to the V

REFA

pin. In 4-quadrant mode, R

ties to R

OFSA

. Do

not connect when operating in unipolar mode.

6 R

COMA

Center Tap Point of the Two 4-Quadrant Resistors, R

and R

. In 4-quadrant mode, R

COMA

ties to the inverting

node of the reference amplifier. In 2-quadrant mode, R

COMA

shorts to the VREF pin. Do not connect if operating in

unipolar mode.

7 V

REFA

DAC A Reference Input in 2-Quadrant Mode, R2 Terminal in 4-Quadrant Mode. In 2-quadrant mode, V

REFA

is the

reference input with constant input resistance versus code. In 4-quadrant mode, V

REFA

is driven by the external

reference amplifier.

8 I

OUTA

DAC A Current Output. Connects to the inverting terminal of external precision I-V op amp for voltage output.

AGNDA

DAC A Analog Ground.

10 DGND

Digital

Ground.

AGNDB

DAC B Analog Ground.

12 I

OUTB

DAC B Current Output. Connects to inverting terminal of external precision I-V op amp for voltage output.

13 V

REFB

DAC B Reference Input Pin. Establishes DAC full-scale voltage. Constant input resistance versus code. If
configured with an external op amp for 4-quadrant multiplying, V

REFB

becomes V

REF

14 R

COMB

Center Tap Point of the Two 4-Quadrant Resistors, R

and R

. In 4-quadrant mode, R

COMB

ties to the inverting

node of the reference amplifier. In 2-quadrant mode, R

COMB

shorts to the VREF pin. Do not connect if operating in

unipolar mode.

15 R

4-Quandrant Resistor. In 2-quadrant mode, R

shorts to the V

REFB

pin. In 4-quadrant mode, R

ties to R

OFSB

. Do not

connect if operating in unipolar mode.

16 R

FBB

Internal Matching Feedback Resistor B. Connects to external op amp for I-V conversion.

17 R

OFSB

Bipolar Offset Resistor B. Accepts up to ±18 V. In 2-quadrant mode, R

OFSB

ties to R

FBB

. In 4-quadrant mode, R

OFSB

ties to R

and an external reference.

AD5547/AD5557

Rev. 0 | Page 7 of 20

Pin No.

Mnemonic

Function

Write Control Digital Input In, Active Low. WR transfers shift register data to the DAC register on the rising edge.
Signal level must be V

+ 0.3 V.

Address Pin 0. Signal level must be V

+ 0.3 V.

Address Pin 1. Signal level must be V

+ 0.3 V.

LDAC

Digital Input Load DAC Control. Signal level must be V

+ 0.3 V.

22 MSB Power-On Reset State. MSB = 0 corresponds to zero-scale reset; MSB = 1 corresponds to midscale reset. The

signal level must be V

+ 0.3 V.

Active low resets both input and DAC registers. Resets to zero-scale if MSB = 0, and to midscale if MSB = 1. Signal
level must be V

+ 0.3 V.

VDD

Positive Power Supply Input. The specified range of operation is 2.7 V to 5.5 V.

Table 4. AD5557 Pin Function Descriptions

Pin No.

Mnemonic

Function

1, 2

No Connection. Do not connect anything other than dummy pads to these pins.

3 R

OFSA

Bipolar Offset Resistor A. Accepts up to ±18 V. In 2-quadrant mode, R

OFSA

ties to R

FBA

. In 4-quadrant mode, R

OFSA

ties

to R

and the external reference.

4 R

FBA

Internal Matching Feedback Resistor A. Connects to the external op amp for I-V conversion.

5 R

4-Quandrant Resistor. In 2-quadrant mode, R

shorts to the V

REFA

pin. In 4-quadrant mode, R

ties to R

OFSA

. Do not

connect when operating in unipolar mode.

6 R

COMA

Center Tap Point of the Two 4-Quadrant Resistors, R

and R

. In 4-quadrant mode, R

COMA

ties to the inverting node

of the reference amplifier. In 2-quadrant mode, R

COMA

shorts to the VREF pin. Do not connect if operating in

unipolar mode.

7 V

REFA

DAC A Reference Input in 2-Quadrant Mode, R2 Terminal in 4-Quadrant Mode. In 2-quadrant mode, V

REFA

is the

reference input with constant input resistance versus code. In 4-quadrant mode, V

REFA

is driven by the external

reference amplifier.

8 I

OUTA

DAC A Current Output. Connects to the inverting terminal of external precision I-V op amp for voltage output.

AGNDA

DAC A Analog Ground.

10 DGND Digital

Ground.

AGNDB

DAC B Analog Ground.

12 I

OUTB

DAC B Current Output. Connects to inverting terminal of external precision I-V op amp for voltage output.

13 V

REFB

DAC B Reference Input Pin. Establishes DAC full-scale voltage. Constant input resistance versus code. If configured
with an external op amp for 4-quadrant multiplying, V

REFB

becomes V

REF

14 R

COMB

Center Tap Point of the Two 4-Quadrant Resistors, R

and R

. In 4-quadrant mode, R

COMB

ties to the inverting node

of the reference amplifier. In 2-quadrant mode, R

COMB

shorts to the VREF pin. Do not connect if operating in

unipolar mode.

15 R

4-Quandrant Resistor. In 2-quadrant mode, R

shorts to the V

REFB

pin. In 4-quadrant mode, R

ties to R

OFSB

. Do not

connect if operating in unipolar mode.

16 R

FBB

Internal Matching Feedback Resistor B. Connects to external op amp for I-V conversion.

17 R

OFSB

Bipolar Offset Resistor B. Accepts up to ±18 V. In 2-quadrant mode, R

OFSB

ties to R

FBB

. In 4-quadrant mode, R

OFSB

ties

to R

and an external reference.

Write Control Digital Input In, Active Low. Transfers shift register data to the DAC register on the rising edge. Signal
level must be V

+ 0.3 V.

Address Pin 0. Signal level must be V

+ 0.3 V.

Address Pin 1. Signal level must be V

+ 0.3 V.

LDAC

Digital Input Load DAC Control. Signal level must be V

+ 0.3 V.

22 MSB Power-On Reset State. MSB = 0 corresponds to zero-scale reset; MSB = 1 corresponds to midscale reset. The signal

level must be V

+ 0.3 V.

Active low resets both input and DAC registers. Resets to zero-scale if MSB = 0, and to midscale if MSB = 1. Signal
level must be V

+ 0.3 V.

2428,
3038

D13 to D0

Digital Input Data Bits D13 to D0. Signal level must be V

+ 0.3 V.

VDD

Positive Power Supply Input. The specified range of operation is 2.7 V to 5.5 V.

AD5547/AD5557

Rev. 0 | Page 9 of 20

TYPICAL PERFORMANCE CHARACTERISTICS

03810-0-006

1.0

0.8

0.6

8192

16384 24576 32768 40960 49152 57344 65536

0.4

0.2

0.4

0.6

0.8

1.0

INL

(
LSB)

CODE (Decimal)

Figure 6. AD5547 Integral Nonlinearity Error

03810-0-007

1.0

0.8

0.6

8192

16384 24576 32768 40960 49152 57344 65536

0.4

0.2

0.4

0.6

0.8

1.0

DNL (LS

)

CODE (Decimal)

Figure 7. AD5547 Differential Nonlinearity Error

03810-0-008

1.0

0.8

0.6

2048

4096

6144

8192

10240 12288 14336 16384

0.4

0.2

0.4

0.6

0.8

1.0

INL (LSB)

CODE (Decimal)

Figure 8. AD5557 Integral Nonlinearity Error

04452-0-010

1.0

0.8

0.6

2048

4096

6144

8192

10240 12288 14336 16384

0.4

0.2

0.4

0.6

0.8

1.0

DNL (LS

)

CODE (Decimal)

Figure 9. AD5557 Differential Nonlinearity Error

03810-0-010

1.5

1.0

DNL

INL

0.5

1.0

1.5

LINE

ARITY

RROR (LS

)

SUPPLY VOLTAGE V

(V)

REF

= 2.5V

= 25

Figure 10. Linearity Error vs. V

03810-0-011

0.5

1.0

1.5

2.0

3.0

3.5

2.5

4.0

4.5

5.0

CURRE

NT I

(LS

)

LOGIC INPUT VOLTAGE V

(V)

= 5V

= 25

Figure 11. Supply Current vs. Logic Input Voltage

AD5547/AD5557

Rev. 0 | Page 10 of 20

03810-0-012

3.0

2.5

10k

100k

10M

100M

2.0

1.5

1.0

0.5

CURRE

NT (mA)

CLOCK FREQUENCY (Hz)

0x5555

0x8000

0xFFFF
0x0000

Figure 12. AD5547 Supply Current vs. Clock Frequency

04452-0-014

100

10k

100k

RR (dB)

FREQUENCY (Hz)

= 5V

10%

REF

= 10V

Figure 13. Power Supply Rejection Ratio vs. Frequency

03810-0-014

LDAC

OUT

CH1

5.00V CH2 2.00V M 200ns

A CH1 2.70V

B CH1

6.20V

400.00ns

Figure 14. Settling Time from Full Scale to Zero Scale

03810-0-015

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

= 5V

REF

= 10V

CODES 0x8000

0x7FFF

TIME (

OUT

(50mV/DIV)

LDAC (5V/DIV)

Figure 15. AD5547 Midscale Transition and Digital Feedthrough

03810-0-016

0xFFFF

0x8000
0x4000

12dB

24dB

36dB

48dB

60dB

72dB

84dB

96dB

108dB

0x2000
0x1000
0x0800
0x0400
0x0200
0x0100
0x0080
0x0040
0x0020
0x0010
0x0008
0x0004
0x0002
0x0001

0x0000

100

100k

10k

10M

START 10.000Hz

STOP 50 000 000.000Hz

REF LEVEL
0.000dB

/DIV
12.000dB

MARKER 4 41 677.200Hz
MAG (A/R) 2.939db

Figure 16. AD5547 Unipolar Reference Multiplying Bandwidth

03810-0-017

12

24

36

48

60

72

84

96

108

120

100

100k

10k

10M

START 10.000Hz

STOP 10 000 000.000Hz

REF LEVEL
0.000dB

/DIV
12.000dB

ALL BITS ON

D15 AND D14 ON

D15 AND D13 ON

D15 AND D12 ON

D15 AND D11 ON

D15 AND D10 ON

D15 AND D9 ON

D15 AND D8 ON

D15 AND D7 ON

D15 AND D6 ON

D15 AND D5 ON

D15 AND D4 ON
D15 AND D3 ON

D15 AND D2 ON

D15 AND D1 ON

D15 AND D0 ON

D15 ON

Figure 17. AD5547 Bipolar Reference Multiplying Bandwidth (Codes from

Midscale to Full Scale)

AD5547/AD5557

Rev. 0 | Page 12 of 20

CIRCUIT OPERATION

D/A CONVERTER SECTION

The AD5547/AD5557 are 16-/14-bit, multiplying, current
output, parallel input DACs. The devices operate from a single
2.7 V to 5.5 V supply, and provide both unipolar (0 V to V

REF

or 0 V to +V

REF

), and bipolar (±V

REF

) output ranges from 18 V

to +18 V references. In addition to the precision conversion R

commonly found in current output DACs, there are three addi-
tional precision resistors for 4-quadrant bipolar applications.

The AD5547/AD5557 consist of two groups of precision R-2R
ladders, which make up the 12/10 LSBs, respectively. Further-
more, the 4 MSBs are decoded into 15 segments of resistor value
2R. Figure 19 shows the architecture of the 16-bit AD5547. Each
of the 16 segments and the R-2R ladder carries an equally
weighted current of one-sixteenth of full scale. The feedback
resistor R

and 4-quadrant resistor R

OFS

have values of 10 k.

Each 4-quadrant resistor, R1 and R2, equals 5 k. In 4-quadrant
operation, R1, R2, and an external op amp work together to
invert the reference voltage and apply it to the VREF input.
With R

OFS

and R

connected as shown in Figure 2, the output

can swing from V

REF

to +V

REF

The reference voltage inputs exhibit a constant input resistance
of 5 k ± 20%. The impedance of I

OUT

, the DAC output, is code

dependent. External amplifier choice should take into account

the variation of the AD5547/AD5557 output impedance. The
feedback resistance in parallel with the DAC ladder resistance
dominates output voltage noise. To maintain good analog
performance, it is recommended that the power supply is
bypassed with a 0.01 µF to 0.1 µF ceramic or chip capacitor in
parallel with a 1 µF tantalum capacitor. Also, to minimize gain
error, PCB metal traces between V

REF

and R

should match.

Every code change of the DAC corresponds to a step function;
gain peaking at each output step may occur if the op amp has
limited GBP and excessive parasitic capacitance present at the
op amp's inverting node. A compensation capacitor, therefore,
may be needed between the I-V op amp inverting and output
nodes to smooth the step transition. Such a compensation
capacitor should be found empirically, but a 20 pF capacitor is
generally adequate for the compensation.

The V

power is used primarily by the internal logic to drive

the DAC switches. Note that the output precision degrades if the
operating voltage falls below the specified voltage. Users should
also avoid using switching regulators because device power
supply rejection degrades at higher frequencies.

04452-0-011

80k

40k

80k

40k

80k

40k

REF

80k

40k

80k

40k

80k

40k

80k

40k

80k

40k

80k

RCOM

ADDRESS DECODER

DAC REGISTER

INPUT REGISTER

LDAC

4 MSB

15 SEGMENTS

8-BIT R2R

4-BIT R2R

LDAC

D15 D14

10k

ROFS

RFB

IOUT
AGND

Figure 19. 16-Bit AD5547 Equivalent R-2R DAC Circuit with Digital Section, One Channel Shown

AD5547/AD5557

Rev. 0 | Page 13 of 20

DIGITAL SECTION

The AD5547/AD5557 have 16-/14-bit parallel inputs. The
devices are double-buffered with 16-/14-bit registers. The dou-
ble-buffered feature allows the simultaneous update of several
AD5547/AD5557s. For the AD5547, the input register is loaded
directly from a 16-bit controller bus when WR is brought low.
The DAC register is updated with data from the input register
when LDAC is brought high. Updating the DAC register
updates the DAC output with the new data (see Figure 19). To
make both registers transparent, tie WR low and LDAC high.
The asynchronous RS pin resets the part to zero scale if the
MSB pin = 0, and to midscale if the MSB pin = 1.

ESD Protection Circuits

All logic input pins contain back-biased ESD protection Zeners
connected to ground (GND) and V

, as shown in Figure 20. As

a result, the voltage level of the logic input should not be greater
than the supply voltage.

03810-0-020

DIGITAL

INPUTS

DGND

Figure 20. Equivalent ESD Protection Circuits

Amplifier Selection

In addition to offset voltage, the bias current is important in op
amp selection for precision current output DACs. A 30 nA input
bias current in the op amp contributes to 1 LSB in the AD5547's
full-scale error. The OP1177 and AD8628 op amps are good
candidates for the I-V conversion.

Reference Selection

The initial accuracy and rated output of the voltage reference
determine the full-span adjustment. The initial accuracy of the
reference is usually a secondary concern because it can be
trimmed. Figure 26 shows an example of a trimming circuit.
The zero-scale error can also be minimized by standard op amp
nulling techniques.

The voltage reference temperature coefficient and long-term
drift are primary considerations. For example, a 5 V reference
with a TC of 5 ppm/°C means the output changes by 25 µV/°C.
As a result, a reference operating at 55°C contributes an
additional 750 µV full-scale error.

Similarly, the same 5 V reference with a ±50 ppm long-term
drift means the output may change by ±250 µV over time.
Therefore, it is practical to calibrate a system periodically to
maintain its optimum precision.

PCB LAYOUT, POWER SUPPLY BYPASSING, AND
GROUND CONNECTIONS

It is a good practice to employ a compact, minimum-lead length
PCB layout design. The leads to the input should be as short as
possible to minimize IR drop and stray inductance.

The PCB metal traces between V

REF

and R

should also be

matched to minimize gain error.

It is also essential to bypass the power supply with quality
capacitors for optimum stability. Supply leads to the device
should be bypassed with 0.01 µF to 0.1 µF disc or chip ceramic
capacitors. Low ESR 1 µF to 10 µF tantalum or electrolytic
capacitors should also be applied at the supply in parallel with
the ceramic capacitor to minimize transient disturbance and
filter out low frequency ripple.

To minimize the digital ground bounce, the AD5547/AD5557
DGND terminal should be joined with the AGND terminal at a
single point. Figure 21 illustrates the basic supply-bypassing
configuration and AGND/DGND connection for the
AD5547/AD5557.

AGND

DGND

0.1

04452-0-015

AD5547/AD5557

Figure 21. Power Supply Bypassing

AD5547/AD5557

Rev. 0 | Page 14 of 20

APPLICATIONS

UNIPOLAR MODE

2-Quadrant Multiplying Mode, V

OUT

= 0 V to V

REF

The AD5547/AD5557 DAC architecture uses a current-steering
R-2R ladder design that requires an external reference and op
amp to convert the unipolar mode of output voltage to

OUT

= V

REF

× D/65,536 (AD5547) (1)

OUT

= V

REF

× D/16,384 (AD5557) (2)

where D is the decimal equivalent of the input code.

In this case, the output voltage polarity is opposite the V

REF

polarity (see Figure 22). Table 7 shows the negative output
versus code for the AD5547.

Table 7. AD5547 Unipolar Mode Negative Output vs. Code

D in Binary

OUT

(V)

1111 1111 1111 1111

REF

(65,535/65,536)

1000 0000 0000 0000

REF

0000 0000 0000 0001

REF

(1/65,536)

0000 0000 0000 0000

LDAC

+2.5V

04452-0-007

AD8628

AD5547/AD5557

16/14 DATA

VDD

COMA

OFSA

FBA

RFB

ROFS

MSB A0, A1

OUTA

AGNDA

2.2pF

C2
0.1

0.1

OUTA

REFA

MSB

A0, A1

LDAC

GND

VOUT

TRIM

ADR03

VIN

+5V

16-/14-BIT

2.5V

0.1

5V

2.5V TO 0V

Figure 22. Unipolar 2-Quadrant Multiplying Mode, V

OUT

= 0 to V

REF

AD5547/AD5557

Rev. 0 | Page 15 of 20

2-Quadrant Multiplying Mode, V

OUT

= 0 V to +V

REF

The AD5547/AD5557 are designed to operate with either
positive or negative reference voltages. As a result, a positive
output can be achieved with an additional op amp, (see
Figure 23); the output becomes

OUT

= +V

REF

× D/65,536 (AD5547) (3)

OUT

= +V

REF

× D/16,384 (AD5557) (4)

Table 8 shows the positive output versus code for the AD5547.

Table 8. AD5547 Unipolar Mode Positive Output vs. Code

D in Binary

OUT

(V)

1111 1111 1111 1111

REF

(65,535/65,536)

1000 0000 0000 0000

REF

0000 0000 0000 0001

REF

(1/65,536)

0000 0000 0000 0000

LDAC

2.5V

+2.5V

0V TO +2.5V

+5V

04452-0-005

AD8628

AD5547/AD5557

16/14 DATA

VDD

COMA

OFSA

FBA

RFB

ROFS

MSB A0, A1

OUTA

AGNDA

U2B

0.1

OUTA

REFA

MSB

A0, A1

LDAC

GND

ADR03

VOUT

TRIM

VIN

U2A

+5V

16-/14-BIT

Figure 23. Unipolar 2-Quadrant Multiplying Mode, V

OUT

= 0 to +V

REF

AD5547/AD5557

Rev. 0 | Page 16 of 20

C6 0.1

C7 1

+10V

10V

15V

10V TO +10V

+15V

04452-0-006

AD8512

AD5547/AD5557

U2A

16/14 DATA

VDD

COMA

OFSA

FBA

RFB

ROFS

MSB A0, A1

OUTA

AGNDA

U2B

C4 1

C2
0.1

0.1

C5 0.1

VOUT

REFA

MSB

A0, A1

LDAC

GND

ADR01

VOUT

TRIM

VIN

+15V

+5V

16-/14-BIT

DAC A

Figure 24. 4-Quadrant Multiplying Mode, V

OUT

= V

REF

to +V

REF

BIPOLAR MODE

4-Quadrant Multiplying Mode, V

OUT

= V

REF

to +V

REF

The AD5547/AD5557 contain on-chip all the 4-quadrant
resistors necessary for precision bipolar multiplying operation.
Such a feature minimizes the number of exponent components
to only a voltage reference, dual op amp, and compensation
capacitor (see Figure 24). For example, with a +10 V reference,
the circuit yields a precision, bipolar 10 V to +10 V output.
Table 9 shows some of the results for the 16-bit AD5547.

OUT

= (D/32768 - 1) × V

REF

(AD5547) (5)

OUT

= (D/16384 - 1) × V

REF

(AD5557) (6)

Table 9. AD5547 Output vs. Code

D in Binary

OUT

1111 1111 1111 1111

REF

(32,767/32,768)

1000 0000 0000 0001

REF

(1/32,768)

1000 0000 0000 0000

0111 1111 1111 1111

REF

(1/32,768)

0000 0000 0000 0000

REF

AD5547/AD5557

Rev. 0 | Page 17 of 20

AC Reference Signal Attenuator

Besides handling the digital waveform decoded from the
parallel input data, the AD5547/AD5557 can also handle low
frequency ac reference signals for signal attenuation, channel
equalization, and waveform generation applications. The
maximum signal range can be up to ±18 V (See Figure 25).

System Calibration

The initial accuracy of the system can be adjusted by trimming
the voltage reference ADR0x with a digital potentiometer (see
Figure 26). The AD5170 provides a one-time programmable
(OTP), 8-bit adjustment that is ideal and reliable for such
calibration. ADI's OTP digital potentiometer comes with
programmable software that simplifies factory calibration.

LDAC

04452-0-008

AD5547/AD5557

16/14 DATA

VDD

OFSA

FBA

RFB

ROFS

MSB A0, A1

OUTA

AGNDA

0.1

OUTA

MSB

A0, A1

LDAC

+10V

10V

+5V

OP2177

COMA

REFA

16-/14-BIT

+15V

U2B

0.1

OP2177

U2A

15V

Figure 25. Signal Attenuator with AC Reference

LDAC

04452-0-009

AD5547/AD5557

16/14 DATA

VDD

OFSA

FBA

RFB

ROFS

MSB A0, A1

OUTA

U2B

+5V

AGNDA

C2
0.1

0.1

OUTA

MSB

A0, A1

LDAC

REF 01/AD

10k

AD5170

+2.5V

470k

+5V

0V TO +2.5V

2.5V

AD8628

COMA

REFA

16-/14-BIT

GND

ADR03

VOUT

TRIM

VIN

0.1

AD8628

Figure 26. Full-Span Calibration

AD5547/AD5557

Rev. 0 | Page 18 of 20

Table 10 lists the latest DACS available from Analog Devices.

Table 10. ADI Current Output DACs

Model Bits

Outputs

Interface

Package Comments

AD5425

SPI, 8-Bit Load

MSOP-10

Fast 8-bit load; see also AD5426.

AD5426

SPI

MSOP-10

Document Outline

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: AD5547BRU

Document Outline

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: AD5547BRU