L9177 datasheet(30/49 Pages) STMICROELECTRONICS

30 / 49 page

Functional description

L9177

30/49

DocID17617 Rev 1

Figure 19. Power-up sequence

Figure 20. Power-down sequence

Reset signal detects a VDD undervoltage longer than UV_Reset_Filter_time by going to low

level. When VDD recovers to normal level Reset signal returns to high level after

Power_On_UV_Reset_Delay time (td_UV_rst). The Reset signal resets all the internal SPI

registers.

4.4

SPI

SPI is a standard four wires interface, that communicates with a data word of 24 bits. By

means of SPI all the channels can be driven in serial way and diagnosis is sent out.Timing

of SPI's operations are reported in Figure 17. The input data (DIN) is read on the rising edge

of the SPI's clock (SCLK), in the same way the output data (DOUT) must be read by the

Microcontroller on the SCLK's rising edge.

4.4.1

Data in (DIN)

DIN command is used to turn On/Off internal channels which do not have Parallel Input

command, and to clear diagnostic latches.

DIN is decoded at the end of the frame if the integrity checks are passed.

L9177 Datasheet(PDF) 30 Page - STMicroelectronics