AD8400AN50 AD [Analog Devices], AD8400AN50 Datasheet

AD8400AN50

Manufacturer Part Number

AD8400AN50

Description

1-/2-/4-Channel Digital Potentiometers

Manufacturer

AD [Analog Devices]

Datasheet

1.AD8400AN50.pdf (20 pages)

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GENERAL DESCRIPTION

The AD8400/AD8402/AD8403 provide a single, dual or quad

channel, 256 position digitally controlled variable resistor (VR)

device. These devices perform the same electronic adjustment

function as a potentiometer or variable resistor. The AD8400

contains a single variable resistor in the compact SO-8 package.

The AD8402 contains two independent variable resistors in

space saving SO-14 surface mount package. The AD8403 con-

tains four independent variable resistors in 24-lead PDIP, SOIC

and TSSOP packages. Each part contains a fixed resistor with a

wiper contact that taps the fixed resistor value at a point deter-

mined by a digital code loaded into the controlling serial input

of the fixed resistor varies linearly with respect to the digital

code transferred into the VR latch. Each variable resistor offers

a completely programmable value of resistance, between the A

terminal and the wiper or the B terminal and the wiper. The

fixed A to B terminal resistance of 1 k , 10 k , 50 k or 100 k

has a 1% channel-to-channel matching tolerance with a nominal

temperature coefficient of 500 ppm/ C. A unique switching cir-

cuit minimizes the high glitch inherent in traditional switched

resistor designs avoiding any make-before-break or break-before-

make operation.

Each VR has its own VR latch that holds its programmed

resistance value. These VR latches are updated from an SPI

compatible serial-to-parallel shift register that is loaded from a

standard 3-wire serial-input digital interface. Ten data bits make

up the data word clocked into the serial input register. The data

word is decoded where the first two bits determine the address

of the VR latch to be loaded, the last eight bits are data. A serial

data output pin at the opposite end of the serial register allows

simple daisy-chaining in multiple VR applications without addi-

tional external decoding logic.

REV. B

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

which may result from its use. No license is granted by implication or

otherwise under any patent or patent rights of Analog Devices.

FEATURES

256 Position

Replaces 1, 2 or 4 Potentiometers

1 k , 10 k , 50 k , 100 k

Power Shut Down—Less than 5 A

3-Wire SPI Compatible Serial Data Input

10 MHz Update Data Loading Rate

+2.7 V to +5.5 V Single-Supply Operation

Midscale Preset

APPLICATIONS

Mechanical Potentiometer Replacement

Programmable Filters, Delays, Time Constants

Volume Control, Panning

Line Impedance Matching

Power Supply Adjustment

loading 80

tor to an end-to-end open circuit condition on the A terminal

and shorts the wiper to the B terminal, achieving a microwatt

power shutdown state. When SHDN is returned to logic high,

the previous latch settings put the wiper in the same resistance

setting prior to shutdown. The digital interface is still active in

shutdown so that code changes can be made which will produce

new wiper positions when the device is taken out of shutdown.

The AD8400 is available in both the SO-8 surface mount and

the 8-lead plastic DIP package.

The AD8402 is available in both surface mount (SO-14) and

the 14-lead plastic DIP package, while the AD8403 is available

in a narrow body 24-lead plastic DIP and the 24-lead surface

mount package. The AD8402/AD8403 are also offered in the

1.1 mm thin TSSOP-14/TSSOP-24 package for PCMCIA ap-

plications. All parts are guaranteed to operate over the extended

industrial temperature range of –40 C to +85 C.

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

Tel: 617/329-4700

Fax: 617/326-8703

The reset (RS) pin forces the wiper to the midscale position by

DGND

CLK

SDI

AD8400/AD8402/AD8403

into the VR latch. The SHDN pin forces the resis-

FUNCTIONAL BLOCK DIAGRAM

AD8403

Digital Potentiometers

World Wide Web Site: http://www.analog.com

CK Q RS

SELECT

A1, A0

SERIAL

DAC

LATCH

10-BIT

SDO

1-/2-/4-Channel

LATCH

8-BIT

RDAC1

RDAC2

RDAC3

RDAC4

SHDN

AGND1

AGND2

AGND3

AGND4

Related parts for AD8400AN50

AD8400AN50 Summary of contents

Page 1

FEATURES 256 Position Replaces Potentiometers 100 k Power Shut Down—Less than 5 A 3-Wire SPI Compatible Serial Data Input 10 MHz Update Data Loading Rate +2.7 ...

AD8400/AD8402/AD8403–SPECIFICATIONS 10 k VERSION ELECTRICAL CHARACTERISTICS Parameter DC CHARACTERISTICS RHEOSTAT MODE Specifications Apply to All VRs 2 Resistor Differential NL 2 Resistor Nonlinearity 3 Nominal Resistance Resistance Tempco Wiper Resistance Nominal Resistance Match DC CHARACTERISTICS POTENTIOMETER DIVIDER Specifications Apply to ...

Page 3

SPECIFICATIONS 50 k & 100 k VERSION ELECTRICAL CHARACTERISTICS Parameter DC CHARACTERISTICS RHEOSTAT MODE Specifications Apply to All VRs 2 Resistor Differential NL 2 Resistor Nonlinearity 3 Nominal Resistance Resistance Tempco Wiper Resistance Nominal Resistance Match DC CHARACTERISTICS POTENTIOMETER DIVIDER ...

Page 4

AD8400/AD8402/AD8403–SPECIFICATIONS 1 k VERSION ELECTRICAL CHARACTERISTICS Parameter DC CHARACTERISTICS RHEOSTAT MODE Specifications Apply to All VRs 2 Resistor Differential NL 2 Resistor Nonlinearity 3 Nominal Resistance Resistance Tempco Wiper Resistance Nominal Resistance Match DC CHARACTERISTICS POTENTIOMETER DIVIDER Specifications Apply to ...

Page 5

AD8400/AD8402/AD8403–SPECIFICATIONS All VERSIONS ELECTRICAL CHARACTERISTICS Parameter 2, 3 SWITCHING CHARACTERISTICS Input Clock Pulse Width Data Setup Time Data Hold Time 4 CLK to SDO Propagation Delay CS Setup Time CS High Pulse Width Reset Pulse Width CLK Fall to CS ...

Page 6

... C to +85 C AD8402AN10 X2/10 - +85 C AD8402AR10 X2/10 - +85 C AD8402ARU10 X2/10 - +85 C AD8403AN10 X4/10 - +85 C AD8403AR10 X4/10 - +85 C AD8403ARU10 X4/10 - +85 C AD8400AN50 X1/50 - +85 C AD8400AR50 X1/50 - +85 C AD8402AN50 X2/50 - +85 C AD8402AR50 X2/50 - +85 C AD8403AN50 X4/50 - +85 C AD8403AR50 X4/50 - +85 C AD8400AN100 X1/100 ...

Page 7

AD8400 PIN DESCRIPTIONS Pin Name Description 1 B1 Terminal B RDAC 2 GND Ground 3 CS Chip Select Input, Active Low. When CS returns high data in the serial input register is loaded into the DAC register. 4 SDI Serial ...

Page 8

AD8400/AD8402/AD8403–Typical Performance Characteristics + 128 160 192 224 256 CODE – Decimal Figure 2. Wiper to End Terminal Resistance vs. Code ...

Page 9

V = +5V DD 600 T = –40 C/+ CONNECT A 500 R MEASURED WB 400 300 200 100 0 –100 128 160 192 224 256 CODE – DECIMAL Figure ...

Page 10

AD8400/AD8402/AD8403 SEE TEST CIRCUIT 33 CODE = + + 10k R = 50k R = 100k 10 100 1k 10k 100k 1M FREQUENCY – Hz Figure 20. Normalized Gain ...

Page 11

DUT 1LSB = V+/256 Figure 29. Potentiometer Divider Nonlinearity Error Test Circuit (INL, DNL) NO CONNECT DUT Figure 30. Resistor Position Nonlinearity Error (Rheostat Operation; R-INL, R-DNL) I ...

Page 12

AD8400/AD8402/AD8403 OPERATION The AD8400/AD8402/AD8403 provide a single, dual and quad channel, 256 position digitally controlled variable resistor (VR) device. Changing the programmed VR settings is accomplished by clocking in a 10-bit serial data word into the SDI (Serial Data Input) ...

Page 13

Dx is the data contained in the 8-bit RDAC# latch, and R is the nominal end-to-end resistance. For example, when and B terminal is open circuit, the following output A resistance values will be ...

Page 14

AD8400/AD8402/AD8403 Table II. Input Logic Control Truth Table CLK CS RS SHDN Register Activity effect, enables SDO pin Shift One bit in from the SDI pin. The tenth previously entered ...

Page 15

The ac characteristics of the RDACs are dominated by the inter- nal parasitic capacitances and the external capacitive loads. The –3 dB bandwidth of the AD8403AN10 (10 k resistor) mea- sures 600 kHz at half scale as a potentiometer divider. ...

Page 16

AD8400/AD8402/AD8403 ACTIVE FILTER One of the standard circuits used to generate a low-pass, high- pass or bandpass filter is the state variable active filter. The digi- tal potentiometer allows full programmability of the frequency, gain and Q of the filter ...

Page 17

Plastic DIP (N-8) 0.430 (10.92) 0.348 (8.84 0.280 (7.11) 0.240 (6.10 0.060 (1.52) PIN 1 0.015 (0.38) 0.210 (5.33) MAX 0.130 (3.30) 0.160 (4.06) MIN 0.115 (2.93) SEATING 0.022 (0.558) 0.100 0.070 (1.77) PLANE (2.54) ...

Page 18

AD8400/AD8402/AD8403 PIN 1 0.210 (5.33) MAX 0.160 (4.06) 0.115 (2.92) PIN 1 0.0118 (0.30) 0.0040 (0.10) 24-Lead Thin Surface Mount TSSOP Package (RU-24) 0.006 (0.15) 0.002 (0.05) SEATING PLANE 24-Pin Narrow Body Plastic DIP Package (N-24 0.280 (7.11) ...

Page 19

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