Application information

L99MOD51XP

20/33

DS12667 Rev 6

4.5

Over-voltage and under-voltage detection

21 V), the outputs OUT1 to OUT5 are switched to high impedance state to protect the load

to the high impedance to avoid the operation of the power devices without sufficient gate

operating voltage the output stages return to the programmed state (input register 0: bit

12 = 0). If the undervoltage / overvoltage recovery disable bit is set, the automatic turn-on of

the drivers is deactivated. The microcontroller needs to clear the status bits to reactivate the

drivers.

4.6

Temperature warning and thermal shutdown

shutdown bit is set and power DMOS transistors of all output stages are switched off to

protect the device. In order to reactivate the output stages the junction temperature must

microcontroller.

4.7

Open-load detection

The open-load detection monitors the load current in each activated output stage. If the load

open-load bit is set in the status register. Due to mechanical/electrical inertia of typical loads

a short activation of the outputs (e.g. 3 ms) can be used to test the open-load status without

changing the mechanical/electrical state of the loads.

4.8

Over load detection

In case of an over-current condition a flag is set in the status register in the same way as

current flag is set and the corresponding driver is switched off to reduce the power

dissipation and to protect the integrated circuit. If the over-current recovery bit of the output

is zero the microcontroller has to clear the status bits to reactivate the corresponding driver.

4.9

Current monitor

The current monitor output sources a current image at the current monitor output which has

a fixed ratio (1/10000) of the instantaneous current of the selected high side driver. The bits

9, 10 and 11 of the input data register 0 control which of the outputs OUT1 to OUT5 are

multiplexed to the current monitor output. The current monitor output allows a more precise

analysis of the actual state of the load rather than the detection of an open- or overload

condition. For example this can be used to detect the motor state (starting, free-running,

stalled). Moreover, it is possible to regulate the power of the defroster more precisely by

measuring the monitor current.