LTC4331 datasheet(6/22 Pages) AD

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LTC4332

Rev. A

For more information www.analog.com

PIN FUNCTIONS

Logic (All Inputs and Outputs Referenced to GND

and VL)

VCC (Pin 1): Main Supply Voltage. 3.0V ≤ VCC ≤ 5.5V.

Bypass with 4.7µF ceramic capacitor to GND.

VL (Pin 2): Logic Interface Supply Voltage. 1.62V ≤ VL ≤

5.5V. Bypass with 1µF ceramic capacitor to GND.

ON (Pin 3): Enable Input. Set high for operation. Set low

for low power mode, in which the internal reset is held,

and outputs are disabled. Connect to VL if unused.

REMOTE (Pin 4): Operating Mode Select Input. Set low

for local SPI slave mode. Set high for SPI master mode

when used on the remote side. REMOTE is weakly pulled

to GND.

LINK (Pin 5): Link Status Open-Drain Output. LINK is

driven low when the device establishes link communi-

cation. Connect to an external pull-up to VL to monitor

status, otherwise float or connect to GND.

SSC (Pin 6): Control Interface Select Input (Active Low).

SSC enables access to the LTC4332 internal control reg-

isters. Set SSC low to initiate a SPI transfer using pins

SCK, MOSI, and MISO. SSC must be set high when the

SPI bus is idle. SSC is only used in local mode (REMOTE

= 0). SSC is weakly pulled to VL and can be unconnected if

not used. When in remote mode, leave SSC unconnected.

SCK (Pin 7): Serial Port Clock. When in local mode, SCK

is an input. MOSI data is captured by the LTC4332 on

the rising edge of SCK. MISO data from the LTC4332 is

updated on the falling edge of SCK. When in remote mode

SCK is an output providing the serial port clock to remote

devices. After startup, the remote side SCK is driven low.

The local side SCK contains a weak bus-hold circuit which

holds the last driven value on the pin if undriven.

MOSI (Pin 8): Master Out Slave In. When in local mode,

MOSI is the serial data input for each of the slave select

pins. MOSI data is captured on the rising edge of SCK.

When in remote mode, MOSI is the serial data output and

can be connected to remote slave devices’ SDI or MOSI

pin. MOSI contains a weak bus-hold circuit which holds

the last driven value on the pin if undriven.

MISO (Pin 9): Master In Slave Out. When in local mode,

MISO is the serial data output for each of the slave select

pins. MISO’s output driver is disabled when SS1-3 and

SSC are high. A weak bus-hold circuit holds the last driven

value to prevent the pin from floating.

When in remote mode, MISO is the serial data input and

can be connected to a remote slave devices’ SDO or MISO

pin. In this mode, MISO is weakly pulled to VL and can be

unconnected if not used.

INT (Pin 10): Remote to Local Interrupt. INT is an open-

drain output in local mode and an input in remote mode.

Values set on the remote side INT propagate to the local

side INT pin. In addition, INT is the level-sensitive active

low interrupt signal for the LTC4332’s control interface.

Connect to an external pull-up to VL on the local side. Do

not allow INT to float on the remote side.

SS1 (Pin 11): Remote Slave Select 1 (Active Low). When

in local mode, SS1 is an input. Set SS1 low to initiate a

remote SPI transfer using pins SCK, MOSI, and MISO.

When in remote mode, SS1 is an output and can be con-

nected to a remote SPI device’s slave or chip select input.

SS1 must be set high when the SPI bus is idle. SS1 is

weakly pulled to VL and can be unconnected if not used.

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