Rainbow Electronics MAX1403 User Manual

General description, Applications, Features

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General Description

The MAX1403 18-bit, low-power, multichannel, serial-
output analog-to-digital converter (ADC) features
matched 200µA current sources for sensor excitation.
This ADC uses a sigma-delta modulator with a digital
decimation filter to achieve 16-bit accuracy. The digital
filter’s user-selectable decimation factor allows the con-
version resolution to be reduced in exchange for a
higher output data rate. True 16-bit performance is
achieved at an output data rate of up to 480sps. In
addition, the modulator sampling frequency may be
optimized for either lowest power dissipation or highest
throughput rate. The MAX1403 operates from +3V.

This device offers three fully differential input channels
that may be independently programmed with a gain
between +1V/V and +128V/V. Furthermore, it can com-
pensate an input-referred DC offset up to 117% of the
selected full-scale range. These three differential chan-
nels may also be configured to operate as five pseudo-
differential input channels. Two additional, fully
differential system-calibration channels are provided for
gain and offset error correction.

The MAX1403 can be configured to sequentially scan all
signal inputs and provide the results via the serial inter-
face with minimum communications overhead. When
used with a 2.4576MHz or 1.024MHz master clock, the
digital decimation filter can be programmed to produce
zeros in its frequency response at the line frequency and
associated harmonics, ensuring excellent line rejection
without the need for further postfiltering.

The MAX1403 is available in a 28-pin SSOP package.

Applications

Portable Industrial Instruments

Portable Weigh Scales

Loop-Powered Systems

Pressure Transducers

Features

18-Bit Resolution, Sigma-Delta ADC

16-Bit Accuracy with No Missing Codes to 480sps

Matched On-Board Current Sources (200µA) for
Sensor Excitation

Low Quiescent Current

250µA (operating mode)
2µA (power-down mode)

3 Fully Differential or 5 Pseudo-Differential Signal
Input Channels

2 Additional, Fully Differential Calibration
Channels/Auxiliary Input Channels

Programmable Gain and Offset

Fully Differential Reference Inputs

Converts Continuously or On Command

Automatic Channel Scanning and Continuous
Data Output Mode

Operates with Analog and Digital Supplies
from +2.7V to +3.6V

SPI™/QSPI™-Compatible 3-Wire Serial Interface

28-Pin SSOP Package

MAX1403

+3V, 18-Bit, Low-Power, Multichannel,

Oversampling (Sigma-Delta) ADC

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Maxim Integrated Products

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28

27

26

25

24

23

22

21

20

19

18

17

16

15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

SCLK

DIN

DOUT

INT

V

DD

DGND

AIN5

CALOFF+

CALOFF-

REFIN+

REFIN-

CALGAIN+

CALGAIN-

AIN6

AIN4

AIN3

AIN2

AIN1

V+

AGND

OUT1

OUT2

DS0

DS1

RESET

CS

CLKOUT

CLKIN

SSOP

TOP VIEW

MAX1403

PART

MAX1403CAI

MAX1403EAI

-40°C to +85°C

0°C to +70°C

TEMP. RANGE

PIN-PACKAGE

28 SSOP

28 SSOP

Pin Configuration

Ordering Information

EVALUATION KIT

AVAILABLE

SPI and QSPI are trademarks of Motorola, Inc.

19-1481; Rev 0; 4/99

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