L9177 datasheet(33/49 Pages) STMICROELECTRONICS

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L9177

Functional description

4.5

Diagnosis

L9177 provides a full set of diagnosis; deglitch timings listed below are digital, generated

from internal clock and their accuracy is guaranteed by scan patterns and clock

measurement.

4.5.1

Voltage regulators thermal warning and shutdown

The 5V linear voltage regulator/tracking regulator is shut down when the thermal shutdown

temperature is reached and also the regulator is in current limitation. The shutdown is

filtered with Tdcg filter of 30 μs ±25 %. As soon as the over temperature disappear the

regulator is switched on again. Over temperature flag without any latch is present via SPI.

4.5.2

Overvoltage shut down

If the VB_off voltage is reached after Tdgc filtering time of 30 μs ±25 % the L9177 enters a

safety state where main outputs are switched-off. Voltage regulators, all low side channels,

stepper motor driver and KLINE are switched off and reset is asserted. As soon as the

battery comes below VB_off minus VB_off_h the L9177 recover standard operation.

4.5.3

Undervoltage shut down

If the VB_UV voltage is reached after analog Tdgc 1 μs ±20 % filtering time the L9177

enters a safety state where main outputs are switched-off. Voltage regulators, all low side

channels, stepper motor driver and KLINE are switched off. As soon as the battery rises

above VB_UV plus the hysteresis the L9177 recovers normal operation.

Figure 21. L9177 under and over voltage time diagram

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