L9952GXP datasheet(23/68 Pages) STMICROELECTRONICS

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L9952GXP

Description

Doc ID 13518 Rev 5

23/68

2.19

LINPU

The LINPU (LIN pull up) signal is set by L9952GXP logic in order to drive the LIN transceiver

in master mode. The master mode is realized by an internal high side switch and an external

diode in series with an external 1k resistor. In master mode the high side switch is closed

causing an external pull up path in parallel to the internal one (diode & 30k resistor).

HS (high side) characteristics:

●

HS does not have an over current protection.

●

The HS remains active in standby mode.

●

Switch off only in case of over temperature (TSD2 = thermal shutdown #2).

●

Typical RDSon, 10 Ω.

The Linpu is activated by default (LIN master mode) and can be switched off with a SPI

command (see register 2) to reduce current in case of LIN shorted to ground.

2.20

Serial Peripheral Interface (SPI)

A 24 bit SPI command (2 adresses + 22 data bits) is used for bi-directional communication

with the micro controller.

During active mode, the SPI:

1) triggers the watchdog

2) controls the modes and status of all L9952GXP modules (incl. input and output drivers)

3) provides driver output diagnostic

4) provide L9952 diagnostic (incl. over temperature warning, L9952GXP operation status)

Note:

During stand-by modes, the SPI is generally deactivated.

The SPI can be driven by a micro controller with its SPI peripheral running in following

mode:

CPOL=0 and CPHA=0.

For this mode input data is sampled by the low to high transition of the clock CLK, and

output data is changed from the high to low transition of CLK.

This device is not limited to micro controller with a build-in SPI. Only three CMOS-

compatible output pins and one input pin will be needed to communicate with the device. A

fault condition can be detected by setting CSN to low. If CSN = 0, the DO-pin will reflect the

global error flag (fault condition) of the device which is a logical -”OR” of all over current, Vs-

over / under voltage, temperature warning/shutdown and V1 Fail bits. The micro controller

can poll the status of the device without the need of a full SPI-communication cycle.

2.20.1

Chip Select Not (CSN)

The input pin is used to select the serial interface of this device. When CSN is high, the

output pin (DO) will be in high impedance state. A low signal activates the output driver and

a serial communication can be started. The state during CSN = 0 is called a communication

frame.

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