1

LTC1272

1272fb

12-Bit, 3

µs, 250kHz

Sampling A/D Converter

■

12-Bit Resolution

µs and 8µs Conversion Times

■

Up to 250kHz Sample Rates

■

On-Chip 25ppm/

°C Reference

■

ESD Protected on All Pins

■

High Speed Data Acquisition

■

Single Supply Systems

The LTC1272 is a 3

µs, 12-bit, successive approximation

sampling A/D converter. It has the same pinout as the

industry standard AD7572 and offers faster conversion

time, on-chip sample-and-hold, and single supply opera-

tion. It uses LTBiCMOS

combine a high speed 12-bit ADC with a fast, accurate

sample-and-hold and a precision reference.

The LTC1272 operates with a single 5V supply but can also

accept the 5V/–15V supplies required by the AD7572 (Pin

23, the negative supply pin of the AD7572, is not connected

on the LTC1272). The LTC1272 has the same 0V to 5V input

range as the AD7572 but, to achieve single supply opera-

tion, it provides a 2.42V reference output instead of the

– 5.25V of the AD7572. It plugs in for the AD7572 if the

reference capacitor polarity is reversed and a 1

µs sample-

and-hold acquisition time is allowed between conversions.

The output data can be read as a 12-bit word or as two

8-bit bytes. This allows easy interface to both 8-bit and

higher processors. The LTC1272 can be used with a

crystal or an external clock and comes in speed grades of

3ms and 8ms.

FREQUENCY (kHz)

0

–140

20

40

60

80

LTC1272 • TA02

–120

–100

–80

–60

–40

–20

0

100

120

S

(N+D)

= 72.1

Single 5V Supply, 3

µs, 12-Bit Sampling ADC

10 F

µ

IN

REF

D11 (MSB)

D10

D9

D8

D7

CLK IN

CLK OUT

HBEN

RD

CS

BUSY

NC

V

LTC1272

D6

D5

D4

DGND

D3/11

D2/10

D1/9

D0/8

A

V

AGND

DD

P

CONTROL

LINES

µ

µ

0.1 F

5V

8 OR 12-BIT

PARALLEL

BUS

ANALOG INPUT

(0V TO 5V)

10

µF

0.1

µF

LTC1272 • TA01

+

+

2.42V

V

OUTPUT

REF

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.

LTBiCMOS is a trademark of Linear Technology Corporation.

All other trademarks are the property of their respective owners.