Control Input Pins

CAL - Calibrate, Pin 4.

When taken high the same time that the CONV pin is taken high the converter will perform a

self-calibration which includes calibration of the offset and gain scale factors in the converter.

CONV - Convert, Pin 3.

The CONV pin initiates a calibration cycle if it is taken from low to high while the CAL pin is

high, or it initiates a conversion if it is taken from low to high with the CAL pin low. If

CONV is held high (CAL low) the converter will do continuous conversions.

BP/UP - Bipolar/Unipolar, Pin 7.

The BP/UP pin selects the conversion mode of the converter. When high the converter will

convert bipolar input signals; when low it will convert unipolar input signals.

A0 - Multiplexer Selection Input, Pin 1.

Selects the input channel for conversion. A0=0=AIN1. A0 is latched when CONV transitions

from low to high. This input has a pull-down resistor internal to the chip.

Measurement and Reference Inputs

AIN1+, AIN2+, AIN1-, AIN2- - Differential Analog Inputs, Pins 8, 9, 10, 11.

Analog differential inputs to the delta-sigma modulator.

VREF+, VREF- - Differential Voltage Reference Inputs, Pins 12, 13.

A differential voltage reference on these pins operates as the voltage reference for the

converter. The voltage between these pins can be any voltage between 1.0 and 3.6 volts.

Power Supply Connections

VA+ - Positive Analog Power, Pin 14.

Positive analog supply voltage. Nominally +5 volts.

VA- - Negative Analog Power, Pin 15.

Negative analog supply voltage. Nominally -5volts.

VD+ - Positive Digital Power, Pin 17.

Positive digital supply voltage. Nominally +5 volts or +3.3 volts.

DGND - Digital Ground, Pin 16.

Digital Ground.

CS5504

DS126F1

21

CS5504

DS126F2

21