CS5521 CS5523
32
DS317PP2
SDO - Serial Data Output.
SDO is the serial data output. It will output a high impedance state if CS = 1.
SCLK - Serial Clock Input.
A clock signal on this pin determines the input/output rate of the data for the SDI/SDO pins
respectively. This input is a Schmitt trigger to allow for slow rise time signals. The SCLK pin
will recognize clocks only when CS is low.
A0, A1 - Logic Outputs.
The logic states of A0-A1 mimic the states of the D22/D10-D23/D11 bits of the channel-setup
register. Logic Output 0 = AGND, and Logic Output 1 = VA+.
Measurement and Reference Inputs
AIN1+, AIN1-, AIN2+, AIN2- AIN3+, AIN3-, AIN4+, AIN4- - Differential Analog Input.
Differential input pins into the CS5521 and CS5523 devices.
VREF+, VREF- - Voltage Reference Input.
Fully differential inputs which establish the voltage reference for the on-chip modulator.
NBV - Negative Bias Voltage.
Input pin to supply the negative supply voltage for the 20X gain instrumentation amplifier and
coarse/fine charge buffers. May be tied to AGND if AIN+ and AIN- inputs are centered around
+2.5 V; or it may be tied to a negative supply voltage (-2.1 V typical) to allow the amplifier to
handle low level signals more negative than ground.
CPD - Charge Pump Drive.
Square wave output used to provide energy for the charge pump.
Power Supply Connections
VA+ - Positive Analog Power.
Positive analog supply voltage. Nom5 V.
VD+ - Positive Digital Power.
Positive digital supply voltage. Nom3.0 V or +5 V.
AGND - Analog Ground.
Analog Ground.
DGND - Digital Ground.
Digital Ground.
