ADS7891

SLAS410 − DECEMBER 2003

14BIT, 3MSPS

LOW POWER SAR ANALOGTODIGITAL CONVERTER

FEATURES

D 3 MHz Sample Rate, 14-Bit Resolution

D Zero Latency

D Unipolar, Pseudo Differential Input, Range:

− 0 V to 2.5 V

D High Speed Parallel Interface

D 78 dB SNR and 88.5 dB THD at 3 MSPS

D Power Dissipation 85 mW at 3 MSPS

D Nap Mode (10 mW Power Dissipation)

D Power Down (10 mW)

D Internal Reference

D Internal Reference Buffer

D 8-/14-Bit Bus Transfer

D 48-Pin TQFP Package

APPLICATIONS

D Optical Networking (DWDM, MEMS Based

Switching)

D Spectrum Analyzers

D High Speed Data Acquisition Systems

D High Speed Close-Loop Systems

D Telecommunication

D Ultra-Sound Detection

DESCRIPTION

The ADS7891 is a 14-bit 3-MSPS A-to-D converter with 2.5-V internal reference. The device includes a

capacitor based SAR A/D converter with inherent sample and hold. The device offers a 14-bit parallel interface

with an additional byte mode that provides easy interface with 8-bit processors. The device has a

pseudo-differential input stage.

The −IN swing of

±200 mV is useful to compensate for ground voltage mismatch between the ADC and sensor

and also to cancel common-mode noise. With nap mode enabled, the device operates at lower power when

used at lower conversion rates. The device is available in a 48-pin TQFP package.

_

+

SAR

Output

Latches

and

3-State

Drivers

BYTE

14/8-Bit Parallel

Data Output Bus

Conversion

and

Control Logic

CONVST

BUSY

CS

RD

A_PWD

PWD/RST

CDAC

Comparator

CLOCK

2.5 V

Internal

Reference

+IN

−IN

REFIN

REFOUT

PRODUCTION DATA information is current as of publication date. Products

conform to specifications per the terms of Texas Instruments standard warranty.

Production processing does not necessarily include testing of all parameters.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments

semiconductor products and disclaimers thereto appears at the end of this data sheet.

Copyright

 2003, Texas Instruments Incorporated