MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA

33996

13

FAULT OPERATION

On each SPI communication, a 24-bit command word is sent

to the 33996 and 24-bit fault word is received from the 33996.

The Most Significant Bit (MSB) is sent and received first.

Command Register Definition:

0 = Output Command Off

1 = Output Command On

SO Definition:

0 = No fault

1 = Fault

APPLICATIONS

Power Consumption

The 33996 has been designed with one Sleep mode and one

consumed by the VPWR pin is less than 10

µA. To place the

33996 in Sleep mode, turn all outputs OFF and remove power

from the SOPWR pin. During normal operation, 500

µA is

supply.

Paralleling of Outputs

Using MOSFETs as output switches allows the connection of

has an inherent positive temperature coefficient, providing

balanced current sharing between outputs without destructive

operation. This mode of operation may be desirable in the event

the application requires lower power dissipation or the added

capability of switching higher currents. Performance of parallel

the Output Current Limit increases correspondingly. Output

OFF Open Load Detect current may increase based on how the

Output OFF Open Load Detect is programmed. Paralleling

outputs from two or more different IC devices is possible but not

recommended.

Care must be taken when paralleling outputs for inductive

loads. The Output Voltage Clamp of the output drivers may not

match. One MOSFET output must be capable of the inductive

energy from the load turn OFF.

SPI Integrity Check

Checking the integrity of the SPI communication is

recommended upon initial power-up of the SOPWR pin. After

initial system start-up or reset, the MCU writes one 48-bit

pattern to the 33996.

The first 24 bits read by the MCU is the fault status of the

outputs, while the second 24 bits is the first bit pattern sent. By

the MCU receiving the same bit pattern it sent, bus integrity is

confirmed. Please note the second 24 bits the MCU sends to

the 33996 are the command bits and will program registers or

Output OFF Open Load Fault

An Output OFF Open Load Fault is the detection and

reporting of an open load when the corresponding output is

disabled (input bit programmed to a logic low state). The Output

OFF Open Load Fault is detected by comparing the drain-to-

Table 2. Fault Operation

Serial Output (SO) Pins Reports

Overtemperature

Fault reported by Serial Output (SO) pin.

Overcurrent

SO pin reports short to battery/supply or overcurrent condition.

Output “ON’ Open Load Fault

Not reported.

Output “OFF’” Open Load Fault

SO pin reports output “OFF’” open load condition.

Device Shutdowns

Overvoltage

recovery all outputs assume previous state or OFF based on the Overvoltage bit in the Global Shutdown/

Retry Control Register.

Overtemperature

Only the output experiencing an overtemperature fault shuts down. Output may auto-retry or remain off

according to the control bits in the Global Shutdown/Retry Control Register.

Overcurrent

Output will remain in current limit 0.9 A to 2.5 A until thermal limit is reached. When thermal limit is reached,

device will enter overtemperature shutdown. Output will operate as programmed in the Global Shutdown/

Retry Control Register. Fault flag in SO Response word will be set.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com