L99H02 datasheet(28/51 Pages) STMICROELECTRONICS

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Device description

L99H02

28/51

DS12547 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.

Note:

In particular when the OV_UV_RD control bit is set to one, two status register clear

operations are needed to reactivate the gate drivers, one to clear the OV/UV flag and turn

on the charge pump and one to clear the CP_LOW flag.

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 drops below

the charge pump low voltage threshold for longer than TCP, the CP_LOW flag is set and all

gate drivers are switched-off (resistive output, see Section 3.4: Resistive low). The

CP_LOW flag 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

detectabled via the SPI. If junction temperature rises above the second threshold TjSDON,

the thermal shutdown flag (TSD) is set and 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: Resistive low). In order to reactivate the output stages the

junction temperature must decrease below TjSD OFF and the thermal shutdown flag 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

reset the corresponding half bridge is in sink condition. The DS_MON flags have to be

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

has a nominal 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 half bridges) configuration are

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

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

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