1

LTC1274/LTC1277

12-Bit, 10mW, 100ksps

ADCs with 1

µA Shutdown

APPLICATI

TYPICAL

S

FEATURE

DESCRIPTIO

The LTC

µs sampling 12-bit A/D

converters which draw only 2mA (typ) from single 5V or

±5V supplies. These easy-to-use devices come complete

with a 2

µs sample-and-hold, a precision reference and an

internally trimmed clock. Unipolar and bipolar conversion

modes add to the flexibility of the ADCs.

Two power-down modes are available in the LTC1277. In

Nap mode, the LTC1277 draws only 180

µA and the instant

wake-up from Nap mode allows the LTC1277 to be pow-

ered down even during brief inactive periods. In Sleep

mode only 1

µA will be drawn. A REFRDY signal is used to

show the ADC is ready to sample after waking up from

Sleep mode. The LTC1274 also provides the Sleep mode

and REFRDY signal.

The A/D converters convert 0V to 4.096V unipolar inputs

from a single 5V supply or

±2.048V bipolar inputs from

±5V supplies.

The LTC1274 has a single-ended input and a 12-bit

parallel data format. The LTC1277 offers a differential

input and a 2-byte read format. The bipolar mode is

formatted as 2’s complement for the LTC1274 and offset

binary for the LTC1277.

s

Low Power Dissipation: 10mW

s

Sample Rate: 100ksps

s

Samples Inputs Beyond Nyquist, 72dB S/(N + D)

s

Single Supply 5V or

±5V Operation

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Power Shutdown to 1

µA in Sleep Mode

s

180

µA Nap Mode (LTC1277) with Instant Wake-Up

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Internal Reference Can Be Overdriven

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Internal Synchronized Clock

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0V to 4.096V or

±2.048V Input Ranges (1mV/LSB)

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24-Lead SO Package

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

Supply Current vs Sample Rate with

Sleep and Nap Modes

SAMPLE RATE (Hz)

10000

1000

100

10

1

0.1

1k

100k

LTC1274/77 • TA02

10

1

10k

100

WITHOUT SLEEP OR NAP

NAP = 5V

(SLEEP MODE)

NAP = REFRDY

(SLEEP MODE)

NAP MODE

S

APPLICATI

s

Battery-Powered Portable Systems

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High Speed Data Acquisition for PCs

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Digital Signal Processing

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Multiplexed Data Acquisition Systems

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Audio and Telecom Processing

s

Spectrum Analysis

1

2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

+

–

AGND

REFRDY

SLEEP

NAP

D7

D6

D5

D4

DGND

BUSY

CS

RD

CONVST

HBEN

D0/8

D1/9

D2/10

D3/11

LTC1277

0.1

µF

+

10

µF

ANALOG

DIFFERENTIAL INPUTS

(0V TO 4.096V)

2.42V

10

µF

0.1

µF

5V

8-BIT

PARALLEL

BUS

µP

CONTROL

LINES

OPTIONAL 3V SUPPLY

TO INTERFACE WITH 3V

PROCESSOR

LTC1274/77 • TA01

+

Single 5V Supply, 10mW, 100kHz, 12-Bit ADC