L9848

Functional description

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3.6

SPI DI input command register

An input byte (8 bits) is routed to the Command Register. The content of this Command

Register is given in Table 8 and Table 9. Additional DI data will continue to be wrapped

around to the DO pin. If CS will go low before a complete reception of the current byte, this

just transmitted byte will be ignored

3.7

Fault operation

The fault diagnostic capability consists of one internal 8bit shift register. Open or shorted

load detection is provided by comparing the source or drain voltage with the VDD voltage.

When an output connected as either a low side device or a high side device is commanded

OFF, an open load can be detected. When an output connected as either a low side device

or a high side device is commanded ON a shorted load can be detected.

The fault bit is "set" for each channel if a short, open, or over-temperature condition occurs

for Outputs1-8. The content of this Fault Register is given in Table 10.

The output load status of each individual channel is defined in Table 11. Open and shorts

are subsequently re-latched provided they meet the minimum duration criterion and thermal

faults will be re-latched provided they meet the duration criterion after CS goes "LOW", if

these fault conditions are still present.

The fault register is capable of detecting and latching multiple fault conditions (among the 8

outputs) that have occurred between clearing of the fault flags.

All of the faults will be cleared on the falling edge of Chip Select (CS).

Table 8.

Bit command register definition

MSB

LSB

OUT8

OUT7

OUT6

OUT5

OUT4

OUT3

OUT2

OUT1

D07D06

D05D04

D03D02

D01

D00

Table 9.

Command register logic definition

Bit

State

Status

D00-D07

0

OUTPUT1-8 are commanded OFF

D00-D07

1

OUTPUT1-8 are commanded ON

Table 10.

Fault register definition

MSB

LSB

Fault8

Fault7

Fault6

Fault5

Fault4

Fault3

Fault2

Fault1

D07

D06

D05

D04

D03

D02

D01

D00

Table 11.

Fault logic definition

BIT

STATE

STATUS

Fault1-8

0

OUT1-8 are not open or shorted (nominal)

Fault1-8

1

OUT1-8 are either open or shorted or in thermal shutdown