Cirrus Logic CS5508 - Manual (Page 28)

Control Input Pins
CAL - Calibrate, Pin 3 (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 2 (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. CONV
latches the multiplexer selection when it transitions from low to high on the multiple channel
devices. If CONV is held high (CAL low) the converter will do continuous conversions.
A0, A1 - Multiplexer Selection Inputs, Pins (1, 24).
A0 and A1 select the input channel for conversion on the multi-channel input devices. A0 and
A1 are latched when CONV transitions from low to high. These two inputs have pull-down
resistors internal to the chip.
BP/UP - Bipolar/Unipolar, Pin 7 (8).
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.
Measurement and Reference Inputs
AIN+, AIN-, (AIN1+, AIN2+, AIN3+, AIN4+, AIN-) - Differential Analog Inputs, Pins 8, 10 (9,
10, 12, 13, 11).
AIN- in the CS5505/6 is a common measurement node for AIN1+, AIN2+, AIN3+ and AIN4+.
VREF+, VREF- - Differential Voltage Reference Inputs, Pins 11, 12 (14, 15).
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.
Voltage Reference
VREFOUT - Voltage Reference Output, Pin 13 (16).
The on-chip voltage reference is output from this pin. The voltage reference has a nominal
magnitude of 2.5 volts and is referenced to the VA+ pin on the converter.
Power Supply Connections
VA+ - Positive Analog Power, Pin 14 (17).
Positive analog supply voltage. Nominally +5 volts.
VA- - Negative Analog Power, Pin 15 (18).
Negative analog supply voltage. Nominally -5 volts when using dual polarity supplies; or 0
volts (tied to system analog ground) when using single supply operation.
CS5505/6/7/8
28 DS59F4
CS5505/6/7/8
28 DS59F7