L99MD01 datasheet(10/54 Pages) STMICROELECTRONICS

10 / 54 page

Detailed description

L99MD01

10/54

Doc ID 17242 Rev 6

2.11

Open-load detection

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

current is below the open-load detection threshold for at least 2 ms (tdOL) the corresponding

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.

2.12

Overload detection

In case of an overcurrent condition, a flag is set in the corresponding status register. If the

overcurrent signal is valid for at least tISC = 32 µs, the overcurrent flag is set and the

corresponding switch is switched off to reduce the power dissipation and to protect the

integrated circuit. The microcontroller has to clear the status bit to reactivate the

corresponding driver.

2.13

Cross-current protection

The device is cross-current protected by an internal delay time. If one driver (LS or HS) is

turned-off the activation of the other driver of the same half bridge are automatically delayed

by the cross-current protection time. After the cross-current protection time is expired the

slew-rate limited switch-off phase of the driver is changed to a fast turn-off phase and the

opposite driver is turned-on with slew-rate limitation. Due to this behavior it is always

guaranteed that the previously activated driver is totally turned-off before the opposite driver

starts to conduct. If wrong SPI commands try to turn-on both driver (LS and HS)

simultaneously, the high-side and the low-side are (or stay) deactivated (3-state).

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