Analog Integrated Circuit Device Data

16

Freescale Semiconductor

33879

FUNCTIONAL DESCRIPTION

SPI DEFINITION

SPI DEFINITION

On each SPI communication, a 16-bit command word is

sent to the 33879 and a 16-bit status word is received from

the 33879. The MSB is sent and received first. As Table

shows, the Command Register defines the position and

Fault Register, shown in Table 6, defines the previous state

status of the output driver. Table identifies the type of fault

and the method by which the fault is communicated to the

microprocessor

0 = Bits 0 to 7, Output commanded OFF.

0 = Bits 8 to 15, Open Load Detection Current OFF.

1 = Bits 0 to 7, Output commanded ON.

1 = Bits 8 to 15 Open Load Detection Current ON.

0 = Bits 0 to 7, No Fault at Output.

1 = Bits 0 to 7, Output Short-to-Battery, Short-to-GND,

Bits 8 to 15 will always return “0”.

Table 6. Command Register Definition

MSB

LSB

Bit 15

Bit 14

Bit 13

Bit 12

Bit 11

Bit 10

Bit 9

Bit 8

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

ON/

OFF

Open

Load

Detect

8

ON/

OFF

Open

Load

Detect

7

ON/

OFF

Open

Load

Detect

6

ON/

OFF

Open

Load

Detect

5

ON/

OFF

Open

Load

Detect

4

ON/

OFF

Open

Load

Detect

3

ON/

OFF

Open

Load

Detect

2

ON/

OFF

Open

Load

Detect

1

ON/

OFF

OUT 8

ON/

OFF

OUT 7

ON/

OFF

OUT 6

ON/

OFF

OUT 5

ON/

OFF

OUT 4

ON/

OFF

OUT 3

ON/

OFF

OUT 2

ON/

OFF

OUT 1

Table 7. Fault Register Definition

MSB

LSB

Bit 15

Bit 14

Bit 13

Bit 12

Bit 11

Bit 10

Bit 9

Bit 8

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

0

0

0

0

0

0

0

0

OUT 8

Status

OUT 7

Status

OUT 6

Status

OUT 5

Status

OUT 4

Status

OUT 3

Status

OUT 2

Status

OUT 1

Status

Table 8. Fault Operation

Serial Output (DO) Pin Reports

Over-temperature

Fault reported by serial output (DO) pin.

Over-current

DO pin reports short to battery/supply or over-current condition.

Output ON Open Load Fault

Not reported.

Output OFF Open Load Fault

DO pin reports output OFF open load condition only with Open Load Detection Current enabled.

DO pin will report “0” for Output OFF Open Load Fault with Open Load Detection Current disabled.

Device Shutdowns

Over-voltage

outputs assuming the previous state upon recovery from over-voltage.

Over-temperature

Only the output experiencing an over-temperature shuts down. Output assumes previous state upon

recovery from over-temperature.