Texas Instruments ADS7870 Handleiding

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SBAS124C − DECEMBER 1999 − REVISED DECEMBER 2005

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FEATURES

DPGA Gains: 1, 2, 4, 5, 8, 10, 16, 20 V/V

DProgrammable Input (Up to 4-Channel

Differential/Up to 8-Channel Single-Ended or

Some Combination)

D1.15-V, 2.048-V, or 2.5-V Internal Reference

DSPI/DSP Compatible Serial Interface

(≤20MHz)

DThroughput Rate: 52 kSamples/sec

DError Overload Indicator

DProgrammable Output 2s Complement/Binary

D2.7-V to 5.5-V Single Supply Operation

D4-Bit Digital I/O Via Serial Interface

DPin-Compatible With ADS7871

DSSOP-28 Package

APPLICATIONS

DPortable Battery-Powered Systems

DLow-Power Instrumentation

DLow-Power Control Systems

DSmart Sensor Applications

DESCRIPTION

The ADS7870(US patents 6140872, 6060874) is a

complete low-power data acquisition system on a single

chip. It consists of a 4-channel differential/8-channel

single-ended multiplexer, precision programmable gain

amplifier, 12-bit successive approximation analog-to-

digital (A/D) converter, and a precision voltage reference.

The programmable-gain amplifier provides high input

impedance, excellent gain accuracy, good common-mode

rejection, and low noise.

For many low-level signals, no external amplification or

impedance buffering is needed between the signal source

and the A/D input.

The offset voltage of the PGA is auto-zeroed. Gains of 1,

2, 4, 5, 8, 10, 16, and 20 V/V allow signals as low as 125

mV to produce full-scale digital outputs.

The ADS7870 contains an internal reference, which is

trimmed for high initial accuracy and stability vs

temperature. Drift is typically 10 ppm/°C. An external

reference can be used in situations where multiple

ADS7870s share a common reference.

The serial interface allows the use of SPI, QSPI,

Microwire, and 8051-family protocols, without glue logic.

12-BIT

A/D

MUX

Serial

Interface

SCLK

CS

Digital

I/O

I/O0

I/O2

I/O3

I/O1

LN0

LN2

LN3

LN1

LN4

LN6

LN7

LN5

Registers

PGA

_

+

RESET

RISE/FALL

DIN

DOUT

BUSY

CONVERT

BUFOUT/REFINBUFIN

Oscillator

CCLK

OSC ENABLE

REF

VREF

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

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

Copyright  1999−2005, Texas Instruments Incorporated

QSPI and SPI are trademarks of Motorola, Inc.

Microwire is a trademark of National Semiconductor Corporation.

All other trademarks are the property of their respective owners.

Product specificaties