WM2638

Dual 12-Bit Serial Input Voltage Output DAC

with Internal reference

Production Data, Rev 1.0, July 1999

WOLFSON MICROELECTRONICS LTD

Lutton Court, Bernard Terrace, Edinburgh, EH8 9NX, UK

Tel: +44 (0) 131 667 9386

Fax: +44 (0) 131 667 5176

Email: sales@wolfson.co.uk

http://www.wolfson.co.uk

Production Data contains final specifications

current on publication date. Supply of products

conforms to Wolfson Microelectronics' Terms

and Conditions.

Last printed 15/07/99 15:58

©1999 Wolfson Microelectronics Ltd

.

FEATURES

•

Two 12-bit voltage output DACs

•

Single 2.7V to 5.5V supply operation

•

DNL

±±0.4 LSBs, INL ±±2 LSBs

•

Low power consumption

•

12mW typical in fast mode

•

6mW typical in slow mode

•

TMS320, (Q)SPI

™

™, and Microwire™

™ compatible

serial interface

•

Programmable settling time 1

µµs or 3.5µµs typical

•

Power down mode 10nA

APPLICATIONS

•

Battery powered test instruments

•

Digital offset and gain adjustment

•

Battery operated/remote industrial controls

•

Machine and motion control devices

•

Cellular telephones

•

Wireless telephones and communication systems

•

Speech synthesis

• Arbitrary waveform generation

ORDERING INFORMATION

DEVICE

TEMP. RANGE

PACKAGE

WM2638CD

0° to 70°C

8-pin SOIC

WM2638ID

-40° to 85°C

8-pin SOIC

DESCRIPTION

The WM2638 is a dual 12-bit voltage output, resistor string, digital-

to-analogue converter. A software controlled power down mode is

provided that reduces current consumption to 10nA.

The WM2638 features an internal programmable voltage reference

simplifying overall system design. A reference voltage may also be

supplied externally.

The device has been designed to interface efficiently to industry

standard microprocessors and DSPs, including the TMS320

family. The WM2638 is programmed with a 16-bit serial word

comprising of a latch address, mode control bits and DAC or

control data.

Excellent performance is delivered with a typical DNL of 0.4LSBs.

The programmable settling time allows the designer to optimise

speed versus power consumption. The output stage is buffered by

a x2 gain near rail-to-rail amplifier.

The device is available in an 8-pin SOIC package ideal for space-

critical applications. Commercial temperature (0° to 70°C) and

Industrial temperature (-40° to 85°C) variants are supported.

BLOCK DIAGRAM

TYPICAL PERFORMANCE

(7) OUTB

(4) OUTA

12-BIT

DAC B

HOLDING

LATCH

12-BIT

DAC A

LATCH

REF(6)

POWER-ON

RESET

DIN (1)

SCLK (2)

NCS (3)

(5)

AGND

POWERDOWN/

SPEED

CONTROL

12-BIT

DAC B

LATCH

DAC

OUTPUT

BUFFER

2-BIT

CONTROL

LATCH

X1

X2

X2

DAC

OUTPUT

BUFFER

REFERENCE

INPUT

BUFFER

REFERENCE

INPUT BUFFER

16-BIT

SHIFT

REGISTER

AND

CONTROL

LOGIC

2-BIT

REFERENCE

SELECT

LATCH

1.024V/2.048V

SELECTABLE

REFERENCE

X1

VDD

(8)

c

X1

REFERENCE

OUTPUT BUFFER

WITH OUPUT

ENABLE

WM2638

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

0

512

1024

1536

2048

2559

3071

3583

4095

DIGITAL CODE