ANALOG DEVICES AD5780 Service Manual

System Ready, 18-Bit ±1 LSB INL,

VCCV

V

Data Sheet

FEATURES

True 18-bit voltage output DAC, ±1 LSB INL 8 nV/√Hz output noise spectral density

0.025 LSB long-term linearity error stability

±0.018 ppm/°C gain error temperature coefficient

2.5 μs output voltage settling time

3.5 nV-sec midscale glitch impulse Integrated precision reference buffers Operating temperature range: −40°C to +125°C 4 mm × 5 mm LFCSP package Wide power supply range of up to ±16.5 V 35 MHz Schmitt triggered digital interface

1.8 V-compatible digital interface

APPLICATIONS

Medical instrumentation Test and measurement Industrial control Scientific and aerospace instrumentation Data acquisition systems Digital gain and offset adjustment Power supply control

Voltage Output DAC

AD5780

FUNCTIONAL BLOCK DIAGRAM

DD

IOV

SDIN

SCLK

SYNC

SDO

LDAC

CLR

RESET

CC

DGND

AD5780

INPUT SHIFT

REGISTE R

CONTROL

LOGIC

POWER-ON RESET AND CLEAR LOG IC

18

AND

SS

AGNDV

Table 1. Related Devices

Part No. Description

AD5790 20-bit, 2 LSB accurate DAC AD5791 20-bit, 1 ppm accurate DAC AD5781 18-bit, 0.5 LSB accurate DAC AD5541A/AD5542A 16-bit, 1 LSB accurate 5 V DAC AD5760 16-bit, 0.5 LSB accurate DAC

DAC REG

REFP

18

Figure 1.

18-BIT

DAC

V

REFN

R1

6.8kΩ

A1

6kΩ

R

FB

6.8kΩ

R

INV

V

FB

OUT

09649-001

GENERAL DESCRIPTION

The AD57801 is a true 18-bit, unbuffered voltage output DAC that operates from a bipolar supply of up to 33 V. The AD5780 accepts a positive reference input range of 5 V to V and a negative reference input range of V

+ 2.5 V to 0 V. Both

SS

reference inputs are buffered on chip and external buffers are not required. The AD5780 offers a relative accuracy specification of ±1 LSB maximum range, and operation is guaranteed monotonic with a ±1 LSB DNL maximum range specification.

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 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. 7,884,747 and 8,089,380.

− 2.5 V

DD

PRODUCT HIGHLIGHTS

1. True 18-bit accuracy.

2. Wide power supply range of up to ±16.5 V.

3. −40°C to +125°C operating temperature range.

4. Low 8 nV/√Hz noise.

5. Low ±0.018 ppm/°C gain error temperature coefficient.

COMPANION PRODUCTS

Output Amplifier Buffer: AD8675, ADA4898-1, ADA4004-1 External Reference: ADR445 DC-to-DC Design Tool: ADIsimPower™ Additional companion products on the AD5780 product page

Rev. C

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her 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.

AD5780 Data Sheet

REVISION HISTORY

3/12—Rev. B to Rev. C

Changes to Data Sheet Title and added Patent 8,089,380........... 1

2/12—Rev. A to Rev. B

Deleted Linearity Compensation Section ................................... 24

12/11—Rev. 0 to Rev. A

Edits to Table 2.................................................................................. 3

Changes to Figure 48...................................................................... 17

Changes to DAC Register Section................................................ 21

Changes to Table 10 and Table 11 ................................................ 22

11/11—Revision 0: Initial Version

Rev. C | Page 2 of 28

Data Sheet AD5780

SPECIFICATIONS

VDD = 12.5 V to 16.5 V, VSS = −16.5 V to −12.5 V, V R

= unloaded, CL = unloaded, T

L

MIN

to T

, unless otherwise noted.

MAX

= 10 V, V

REFP

= −10 V, VCC = 2.7 V to 5.5 V, IOVCC = 1.71 V to 5.5 V,

REFN

Table 2.

A, B Versions

1

Parameter Min Typ Max Unit Test Conditions/Comments

STATIC PERFORMANCE2

Resolution 18 Bits Integral Nonlinearity Error (Relative

Accuracy)

−1 +1 LSB B grade, V

−2 +2 LSB A grade, V Differential Nonlinearity Error −0.25 +0.75 LSB B grade, V

−1 +1 LSB A grade, V

−0.85 +0.85 LSB B grade, V = 25°C

T

A

= +10 V, V

REFP

= ±10 V, +10 V, and +5 V

REFx

= ±10 V, +10 V, and +5 V

REFx

= ±10 V, +10 V, and +5 V

REFx

= ±10 V, +10 V, and +5 V

REFx

= −10 V,

REFN

Long-Term Linearity Error Stability3 0.025 LSB After 750 hours at TA = 135°C Full-Scale Error −3 ±0.95 +3 LSB V

−5.5 ±0.675 +0.5 LSB V

−10 ±0.45 +10 LSB V Full-Scale Error Temperature Coefficient ±0.026 ppm/°C V Zero-Scale Error −4.8 ±0.325 +4.8 LSB V

−10 ±0.175 +10 LSB V

−20.5 ±0.225 +20.5 LSB V Zero-Scale Error Temperature

±0.025 ppm/°C V

= +10 V, V

REFP

= 10 V, V

REFP

= 5 V, V

REFP

= +10 V, V

REFP

= +10 V, V

REFP

= 10 V, V

REFP

= 5 V, V

REFP

= +10 V, V

REFP

REFN

= 0 V

REFN

= 0 V

REFN

= −10 V

= 0 V

= −10 V = −10 V

= 0 V

= −10 V

Coefficient Gain Error −19 ±2.3 +19 ppm FSR V

−35 ±1.9 +35 ppm FSR V

−68 ±0.9 +68 ppm FSR V Gain Error Temperature Coefficient ±0.018 ppm/°C V

= +10 V, V

REFP

= 10 V, V

REFP

= 5 V, V

REFP

= +10 V, V

REFP

REFN

= 0 V

REFN

= −10 V

= 0 V

= −10 V

R1, RFB Matching 0.015 %

OUTPUT CHARACTERISTICS

Output Voltage Range V Output Voltage Settling Time 2.5 μs

V

REFN

REFP

V

10 V step to 0.02%, using the ADA4898-1 buffer in unity-gain mode

3.5 μs 500 code step to ±1 LSB4 Output Noise Spectral Density 8 nV/√Hz At 1 kHz, DAC code = midscale 8 nV/√Hz At 10 kHz, DAC code = midscale Output Voltage Noise 1.1 μV p-p

DAC code = midscale, 0.1 Hz to 10 Hz bandwidth

Midscale Glitch Impulse4 14 nV-sec V

3.5 nV-sec V 4 nV-sec V MSB Segment Glitch Impulse4 14 nV-sec V

3.5 nV-sec V 4 nV-sec V

= +10 V, V

REFP

= 10 V, V

REFP

= 5 V, V

REFP

= +10 V, V

REFP

= 10 V, V

REFP

= 5 V, V

REFP

= −10 V

REFN

= 0 V

REFN

= 0 V

REFN

= −10 V, see Figure 43

REFN

= 0 V, see Figure 44

REFN

= 0 V, see Figure 45

REFN

Output Enabled Glitch Impulse 57 nV-sec On removal of output ground clamp Digital Feedthrough 0.27 nV-sec DC Output Impedance (Normal Mode) 3.4 kΩ DC Output Impedance (Output

6 kΩ

Clamped to Ground)

Rev. C | Page 3 of 28

AD5780 Data Sheet

A, B Versions

1

Parameter Min Typ Max Unit Test Conditions/Comments

REFERENCE INPUTS

V

Input Range 5 VDD − 2.5 V

REFP

V

Input Range VSS + 2.5 0 V

REFN

Input Bias Current −20 −0.63 +20 nA

−4 −0.63 +4 Input Capacitance 1 pF V

TA = 0°C to 105°C

, V

REFN

REFP

LOGIC INPUTS

Input Current5 −1 +1 μA Input Low Voltage, VIL 0.3 × IOVCC V IOVCC = 1.71 V to 5.5 V Input High Voltage, VIH 0.7 × IOVCC V IOVCC = 1.71 V to 5.5 V Pin Capacitance 5 pF

LOGIC OUTPUT (SDO)

Output Low Voltage, VOL 0.4 V IOVCC = 1.71 V to 5.5 V, sinking 1 mA Output High Voltage, VOH IOVCC − 0.5 V IOVCC = 1.71 V to 5.5 V, sourcing 1 mA High Impedance Leakage Current ±1 μA High Impedance Output Capacitance 3 pF

POWER REQUIREMENTS All digital inputs at DGND or IOVCC

VDD 7.5 VSS + 33 V VSS V

− 33 −2.5 V

DD

VCC 2.7 5.5 V IOVCC 1.71 5.5 V IOVCC ≤ VCC IDD 10.3 14 mA ISS −10 −14 mA ICC 600 900 μA IOICC 52 140 μA SDO disabled DC Power Supply Rejection Ratio ±7.5 μV/V ∆VDD ± 10%, VSS = −15 V ±1.5 μV/V ∆VSS ± 10%, VDD = 15 V AC Power Supply Rejection Ratio 90 dB ∆VDD ± 200 mV, 50 Hz/60 Hz, VSS = −15 V 90 dB ∆VSS ± 200 mV, 50 Hz/60 Hz, VDD = 15 V

1

Temperature range: −40°C to +125°C, typical conditions: TA = 25°C, VDD = +15 V, VSS = −15 V, V

2

Performance characterized with the 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

The AD5780 is configured in the unity-gain 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).

5

Current flowing in an individual logic pin.

= +10 V, V

REFP

= −10 V.

REFN

Rev. C | Page 4 of 28

Data Sheet AD5780

TIMING CHARACTERISTICS

VCC = 2.7 V to 5.5 V; all specifications T

Table 3.

Parameter

2

t

40 28 ns min SCLK cycle time

1

IOVCC = 1.71 V to 3.3 V IOVCC = 3.3 V to 5.5 V

92 60 ns min SCLK cycle time (readback and daisy-chain modes) t2 15 10 ns min SCLK high time t3 9 5 ns min SCLK low time t4 5 5 ns min t5 2 2 ns min

t6 48 40 ns min t7 8 6 ns min t8 9 7 ns min Data setup time

t9 12 7 ns min Data hold time t10 13 10 ns min

t11 20 16 ns min t12 14 11 ns min t13 130 130 ns typ t14 130 130 ns typ t15 50 50 ns min t16 140 140 ns typ t17 0 0 ns min t18 65 60 ns max t19 62 45 ns max SCLK rising edge to SDO valid (CL = 50 pF)

t20 0 0 ns min t21 35 35 ns typ t22 150 150 ns typ

1

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.

2

Maximum SCLK frequency is 35 MHz for write mode and 16 MHz for readback and daisy-chain modes.

MIN

Limit1

to T

, unless otherwise noted.

MAX

Unit Test Conditions/Comments

to SCLK falling edge setup time

SYNC SCLK falling edge to SYNC Minimum SYNC

rising edge to next SCLK falling edge ignore

SYNC

falling edge to SYNC falling edge

LDAC

rising edge to LDAC falling edge

SYNC

pulse width low

LDAC

falling edge to output response time

LDAC

rising edge to output response time (LDAC tied low)

SYNC

pulse width low

CLR

pulse activation time

CLR

falling edge to first SCLK rising edge

SYNC

rising edge to SDO tristate (CL = 50 pF)

SYNC

rising edge to SCLK rising edge ignore

SYNC

pulse width low

RESET

pulse activation time

RESET

high time

rising edge hold time

Rev. C | Page 5 of 28

AD5780 Data Sheet

SCLK

t

9

t

15

SYNC

SDIN

LDAC

V

OUT

V

OUT

CLR

t

6

t

4

t

8

DB23 DB0

t

10

t

16

t

1

3

t

2

t

7

2421

t

5

t

11

t

14

12

t

13

SCLK

SYNC

SDIN

SDO

V

OUT

RESET

V

OUT

t

21

t

22

t

17

t

6

t

4

t

8

DB23 DB0

INPUT WORD SPECIFIES REGISTER TO BE READ

t

3

t

9

Figure 2. Write Mode Timing Diagram

t

1

t

2

t

7

t

5

24221241

t

17

NOP CONDIT ION

DB23 DB0

t

19

09649-002

t

20

t

5

t

18

REGISTER CONTENTS CL OCKED OUT

Figure 3. Readback Mode Timing Diagram

Rev. C | Page 6 of 28

09649-003

Data Sheet AD5780

t

20

t

5

t

18

09649-004

SCLK

SYNC

SDIN

SDO

t

17

12 24 4825

t

6

t

4

t

8

DB23

INPUT WORD FOR DAC N

DB23

t

3

t

9

UNDEFINED

1

26

t

2

DB0 DB23 DB0

INPUT WORD FOR DAC N – 1

t

19

DB0 DB23 DB0

INPUT WORD FOR DAC N

Figure 4. Daisy-Chain Mode Timing Diagram

Rev. C | Page 7 of 28

AD5780 Data Sheet

ABSOLUTE MAXIMUM RATINGS

TA = 25°C, unless otherwise noted. Transient currents of up to 100 mA do not cause SCR latch-up.

Table 4.

Parameter Rating

VDD to AGND −0.3 V to +34 V VSS to AGND −34 V to +0.3 V VDD to VSS −0.3 V to +34 V VCC to DGND −0.3 V to +7 V IOVCC to DGND

Digital Inputs to DGND

V

to AGND −0.3 V to VDD + 0.3 V

OUT

V

to AGND −0.3 V to VDD + 0.3 V

REFP

V

to AGND VSS − 0.3 V to +0.3 V

REFN

DGND to AGND −0.3 V to +0.3 V Operating Temperature Range, TA

Industrial −40°C to +125°C Storage Temperature Range −65°C to +150°C Maximum Junction Temperature,

max

T

J

Power Dissipation (TJ max − TA)/θJA LFCSP Package

θJA Thermal Impedance 31.0°C/W Lead Temperature JEDEC industry standard

Soldering J-STD-020 ESD (Human Body Model) 1.6 kV

−0.3 V to V (whichever is less)

−0.3 V to IOV +7 V (whichever is less)

150°C

+ 3 V or +7 V

CC

+ 0.3 V or

CC

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 1.6 kV, and it is ESD sensitive. Proper precautions must be taken for handling and assembly.

ESD CAUTION

Rev. C | Page 8 of 28

Data Sheet AD5780

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

FB

DNC

R

22

23 DNC

24 INV

21

20

GND

1

V

OUT

2

V

REFP

3

V

DD

RESET

V

DD

CLR

LDAC

NOTES

= DO NOT CONNECT. DO NOT CONNECT

1. DNC

2. NEGATIVE ANALOG A VOLTAGE I N THE RANG

CAN BE CONNECTED. V

GND. THE PADDLE CAN BE LEFT ELECT

TO A UNCONNECTED PRO CONNECTION IS MADE AT THE VSS RECOMM CON

ENDED THAT THE PADDLE BE THERMAL

NECTED TO A COPP

THERMAL PERFORMANCE.

AD5780

4

TOP VIEW

(Not to Scale)

5 6 7

9

8

10

CC

V

DNC

IOV

SUPPLY CONNECTION (V

E OF –16.5 V TO –2.5 V SHOULD BE D

SS

VIDED THAT A S

ER PLANE FOR ENHANCED

11

SDO

Figure 5. Pin Configuration

Table 5. Pin Function Descriptions

Pin No. Mnemonic Description

1 V 2 V 3, 5 VDD Positive Analog Supply Connection. A voltage in the range of 7.5 V to 16.5 V can be connected to this pin. VDD must be

4 6

7

8 VCC Digital Supply. Voltage range is from 2.7 V to 5.5 V. VCC should be decoupled to DGND. 9 IOVCC Digital Interface Supply. Digital threshold levels are referenced to the voltage applied to this pin. Voltage range is from

10, 21, 22, 23

11 SDO Serial Data Output. 12 SDIN Serial Data Input. This device has a 24-bit input shift register. Data is clocked into the register on the falling edge of the

13 SCLK Serial Clock Input. Data is clocked into the input shift register on the falling edge of the serial clock input. Data can be

14

15 DGND Ground Reference Pin for Digital Circuitry. 16 V 17, 18 VSS Negative Analog Supply Connection. A voltage in the range of −16.5 V to −2.5 V can be connected to this pin.

19 AGND Ground Reference Pin for Analog Circuitry. 20 RFB 24 INV EPAD VSS Negative Analog Supply Connection (VSS). A voltage in the range of −16.5 V to −2.5 V can be connected to this pin. VSS

Analog Output Voltage.

OUT

Positive Reference Voltage Input. A voltage in the range of 5 V to VDD − 2.5 V can be connected to this pin.

REFP

decoupled to AGND. RESET CLR

Active Low Reset. Asserting this pin returns the AD5780 to its power-on status.

Active Low Input. Asserting this pin sets the DAC register to a user defined value (see

output. The output value depends on the DAC register coding that is being used, either binary or twos complement. LDAC

Active Low Load DAC Logic Input. This pin 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

the input register is updated, but the output update is held off until the falling edge of

unconnected.

1.71 V to 5.5 V.

DNC Do Not Connect. Do not connect to these pins.

serial clock input.

transferred at rates of up to 35 MHz. SYNC

Level Triggered Control Input (Active Low). This is the frame synchronization signal for the input data. When

low, it enables the input shift register, and data is then transferred in on the falling edges of the following clocks. The DAC

is updated on the rising edge of

Negative Reference Voltage Input.

REFN

must be decoupled to AGND.

V

SS

SYNC

.

Feedback Connection for External Amplifier. See the

Inverting Input Connection for External Amplifier. See the

must be decoupled to AGND. The paddle can be left electrically unconnected provided that a supply connection is made

at the V

pins. It is recommended that the paddle be thermally connected to a copper plane for enhanced thermal

SS

performance.

A

19

V

18

SS

V

17

SS

V

16

REFN

DGND

15

SYNC

14

SCLK

13

12

SDIN

TO THIS PIN.

).

SS

ECOUPLED

RICALLY

UPPLY

PINS. IT IS

LY

09649-005

Table 12) and updates the DAC

LDAC

SYNC

. If

is held high during the write cycle, LDAC

AD5780 Features section for further details.

. Do not leave the

LDAC

SYNC

goes

Rev. C | Page 9 of 28

ANALOG DEVICES AD5780 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

FEATURES

APPLICATIONS

FUNCTIONAL BLOCK DIAGRAM

GENERAL DESCRIPTION

PRODUCT HIGHLIGHTS

COMPANION PRODUCTS

TABLE OF CONTENTS

REVISION HISTORY

SPECIFICATIONS

TIMING CHARACTERISTICS

ABSOLUTE MAXIMUM RATINGS

ESD CAUTION

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS