33480 datasheet(18/39 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33480

FUNCTIONAL DESCRIPTION

FUNCTIONAL TERMINAL DESCRIPTION

SERIAL INPUT (SI)

The SI terminal is a serial interface command data input

terminal. Each SI bit is read on the falling edge of SCLK. A

16-bit stream of serial data is required on the SI terminal,

starting with D15 to D0. SI has an internal pulldown, Idown.

SERIAL OUTPUT (SO)

The SO data terminal is a tri-stateable output from the shift

until the CS terminal is put into a logic [0] state. The SO data

is capable of reporting the status of the output, the device

configuration, and the state of the key inputs. The SO

terminal changes state on the rising edge of SCLK and reads

out on the falling edge of SCLK.

CHIP SELECT (CS)

The CS terminal enables communication with the master

device. When this terminal is in a logic [0] state, the device is

capable of transferring information to, and receiving

information from, the master device. The 33480 device

latches in data from the Input Shift registers to the addressed

registers on the rising edge of CS. The device transfers status

information from the power output to the Shift register on the

falling edge of CS. The SO output driver is enabled when CS

is logic [0]. CS should transition from a logic [1] to a logic [0]

state only when SCLK is a logic [0]. CS has an internal pullup,

IUP.

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