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LTC1277

12-Bit, 10mW, 100ksps ADCs with 1µA Shutdown

Linear Technology 

LTC1274/LTC1277

12-Bit, 10mW, 100ksps

ADCs with 1µA Shutdown

FEATURES

■ Low Power Dissipation: 10mW

■ Sample Rate: 100ksps

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

and 82dB THD at fIN = 100kHz

■ Single Supply 5V or ±5V Operation

■ Power Shutdown to 1µA in Sleep Mode

■ 180µA Nap Mode (LTC1277) with Instant Wake-Up

■ Internal Reference Can Be Overdriven

■ Internal Synchronized Clock

■ 0V to 4.096V or ±2.048V Input Ranges (1mV/LSB)

■ 24-Lead SO Package

APPLICATI S

■ Battery-Powered Portable Systems

■ High Speed Data Acquisition for PCs

■ Digital Signal Processing

■ Multiplexed Data Acquisition Systems

■ Audio and Telecom Processing

■ Spectrum Analysis

DESCRIPTIO

The LTC®1274/LTC1277 are 8µs 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 2µs 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 180µA 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 1µA 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.

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

TYPICAL APPLICATI

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

LTC1277

2.42V

VREF OUTPUT

ANALOG 1

DIFFERENTIAL INPUTS 2

(0V TO 4.096V) 3

+

4

10µF

0.1µF 5

6

7

8

9

10

8-BIT 11

PARALLEL

BUS

12

AIN+

AIN–

VREF

AGND

REFRDY

SLEEP

NAP

D7

D6

D5

D4

DGND

24

VDD 23

VSS 22

BUSY

21

CS

20

RD

19

CONVST

18

HBEN

17

VLOGIC 16

D0/8

15

D1/9

14

D2/10

13

D3/11

+

10µF

µP

CONTROL

LINES

5V

0.1µF

OPTIONAL 3V SUPPLY

TO INTERFACE WITH 3V

PROCESSOR

LTC1274/77 • TA01

Supply Current vs Sample Rate with

Sleep and Nap Modes

10000

CREF = 4.7µF

WITHOUT SLEEP OR NAP

1000

NAP MODE

100

10

1

0.1

NAP = REFRDY

(SLEEP MODE)

NAP = 5V

(SLEEP MODE)

1 10 100 1k 10k 100k

SAMPLE RATE (Hz)

LTC1274/77 • TA02

1

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