CS5181
SDO, SDO — Serial Data Out
Serial Data Output. Output pin for 16-bit serial data word. The SDO output is the complement
of SDO and helps to reduce radiated noise if the two lines are run adjacent on the PC board
layout. Output data is output in twos complement format MSB first.
FSO — Frame Sync Output
Frame Sync Output. The Frame Sync Output turns low to indicate the beginning of an output
word from the SDO pin. It returns high after the 16 data bits have been clocked out.
Control Pins
RESET — Reset and Calibration
When the RESET pin is pulled to a logic low the converter will perform a reset of its digital
logic. When the level on this pin is brought back to a logic high the chip starts normal
operation, following a two clock cycle delay period. When MODE = 1, the chip goes through
an internal gain and offset calibration routine following this reset sequence.
PWDN — Power Down Mode
A logic 0 on the PWDN pin will put the device into a power-down mode.
MODE — Modulator Only Mode
MODE is held at a logic high for normal operation. In normal operation the device utilizes the
digital decimation filter and calibration ciruitry. MODE = 0 puts the part in modulator only
mode whereby most of the digital circuitry is powered-down and the modulator bit-stream is
output from the SDO and SDO pins.
SYNC — Synchronization of Filter
The SYNC input can be used to restart the digital filter of the converter at the beginning of its
convolution cycle. The SYNC input is used to synchronize the filters of multiple converters in
a system. When the SYNC signal goes high, the filter will be initialized and will begin its
convolution cycle on the next rising edge of MCLK. If not used, tie SYNC to DGND.
MFLAG — Invalid Conversion Flag
MFLAG goes high if the modulator portion of the converter goes unstable. If MFLAG is high,
the output data from the converter may be invalid.
MCLK, MCLK — Master Clock Signal
Master clock input accepts a CMOS level clock input to the converter with worst case duty
cycle of 45-55% (typically 40 MHz). MCLK is not actually used inside the device, but can be
used for radiated noise cancellation if MCLK and MCLK are run adjacent to each other on the
PC board.
DS250PP1
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