L99H01 datasheet(28/53 Pages) STMICROELECTRONICS

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Device description

L99H01

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DocID15567 Rev 6

VVS_UV, all gate driver stages are switched in the sink condition to avoid driving the power

devices without sufficient gate driving voltage (increased power dissipation), setting the UV

bit. In both cases, overvoltage and undervoltage detection, the charge pump is disabled. If

the supply voltage VS recovers from UV/OV to normal operating voltage range and if the

OV_UV_RD is set to 0, then the charge pump is automatically enabled. In any case,

regardless of the OV_UV_RD bit value, the microcontroller needs to clear the status register

to reactivate the gate drivers.

3.7

Charge pump

The charge pump uses 2 external capacitors. The output of the charge pump has a current

limitation. In standby mode and after overvoltage, undervoltage or a thermal shutdown has

been triggered the charge pump is disabled. If the charge pump output voltage remains too

low for longer than TCP , all gate drivers are switched-off (resistive output, see Section 3.4).

The CP_LOW bit has to be cleared through a software reset to reactivate the gate drivers.

3.8

Temperature warning and thermal shutdown

If junction temperature rises above TjTWON the temperature warning flag TW is set and is

detectable via the SPI. If junction temperature increases above the second threshold

TjSDON, the thermal shutdown bit (TSD) is set. The gate drivers and the charge pump are

switched-off to protect the device. The gates of the H-bridge are discharged by the resistive

low mode (see Section 3.4). In order to reactivate the output stages the junction

temperature must decrease below TjSDOFF and the thermal shutdown bit has to be cleared

by the microcontroller.

3.9

Short-circuit detection / drain source monitoring

The drain - source voltage of each activated external MOSFET of the H-bridge is monitored

by comparators to detect shorts to ground or battery. If the voltage drop over the external

MOSFET exceeds the threshold voltage VSCd for longer than the short current detection

time tSCd the corresponding gate driver switches the external MOSFET off and the

corresponding drain source monitoring flag (DS_MON [3:0]) is set. Until this failure flag is

reseted the corresponding half bridge is in sink condition. The DS_MON bits have to be

cleared through a software reset to reactivate the gate drivers. The drain source monitoring

has a filter time of 6 µs. This monitoring is only active when the corresponding gate driver is

in source condition. The threshold voltage VSCd can be programmed in 4 steps between

0.5 V and 2 V with the SPI.

3.10

Programmable cross current protection

The external Power MOSFET’s transistors in H-bridge (two halfbridges) configuration are

switched-on with an additional delay time tCCP to prevent cross current in the halfbridge.

The cross current protection time tCCP can be programmed with the SPI.

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