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L9929

4

Diagnostic

The Diagnosis-Mode can be selected between SPI-Diagnosis and Status-Flag Diagnosis.

The choise of the Diagnosis-Mode is selected by the voltage-level on pin 12 (DMS Diagnosis Mode Selection).

DMS = GND

Status-Flag

DMS = Vcc

SPI-Diagnostic

For the connection of pins SI, SO, SS and SCK/SF see Fig. 13 respectively Fig. 14.

4.1

Status-Flag

The Status-Flag showes the condition „tristate“.

At the following fault-cases the output-stages switches in tristate and set the status-flag from high to low.

- Short circuit between OUT1 and OUT2

- Overcurrent

- Overtemperature

In cause of short circuit or overcurrent, the fault will be stored.

The output stage switches in tristate and the status-flag is set from high level to low-level if the specified value

is exceeded.

If the voltage level changes from high to low on DI or from low to high on EN, the output stage switches on again

and the status-flag is reset to high-level.

In cause of overtemperature the fault will be stored.

The output stage switches in tristate and the status-flag is set from high level to low-level if the specified value

is exceeded.

If the voltage level changes from high to low on DI or from low to high on EN, the output stage switches on again

and the status-flag is reset to high-level.

to low-level if the specified value is fallen. If the voltage has risen about the specified value again, the output

stage switches on again and the status-flag is reset to high-level.

When the maximum current value is reached, the output stages are switched tristate for a fixed time.

According to the time-constant the current decreases exponentially until the next switch-on occurs.

At the end if the fixed time the output stage switches on again and the status-flag is reset to high-level.

5SPI-INTERFACE

5.1

General Discription

The serial SPI interface establishes a communication link between L9929 and the systems microcontroller.

L9929 always operates in slave mode whereas the controller provides the master function.

The maximum baud rate is 2 MBaud (200pF).

Applying an active slave select signal at SS L9929 is selected by the SPI master. SI is the data input (Slave In),

SO the data output (Slave Out). Via SCK (Serial Clock Input) the SPI clock is provided by the master.

In case of inactive slave select signal (High) the data output SO goes into tristate.