L99H02 datasheet(27/51 Pages) STMICROELECTRONICS

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DS12547 Rev 6

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L99H02

Device description

Symbols:



x: Don't care



1: Logic high or active



0: Logic low or not active



H: Output in source condition



L: Output in sink condition



RL: Resistive low (see Section 3.4: Resistive low)



T: Tristate



FW: Free wheeling



FW_PAS: Free wheeling passive



CP_LOW: Charge pump low



OV: Overvoltage



UV: Undervoltage



DS_MON: Short-circuit



TSD: Thermal shutdown



GL_ER: Global error flag

3.4

Resistive low

The resistive low output mode protects the L99H02 and the H-bridge in standby mode and

in some failure modes (internal thermal shutdown (TSD), charge pump low (CP_LOW),

stucked reset (STK_RESET_Q) and power-on reset (POR). When a gate driver changes

into the resistive low output mode due to a failure a sequence is started. In this sequence

the concerning driver is switched in sink condition for 32 µs to 64 µs to ensure a fast switch-

off of the H-bridge transistor. Afterwards the driver is switched in the resistive output mode

(resistive path to source).

3.5

Diagnostic functions

The diagnostic functions (over load, power supply over- and undervoltage, charge pump

low, watchdog, temperature warning and internal/external thermal shutdown) are internally

filtered and the condition has to be valid for at least 64 µs (6 µs for a short-circuit) before the

corresponding status bit in the status registers is set. The filters are used to improve the

noise immunity of the device. The internal temperature warning function is intended for

information purpose and does not change the state of the output drivers. On the contrary,

the over load condition switches the corresponding half bridge in sink condition. The internal

thermal shutdown condition and charge pump low disable all drivers (resistive low). The

external thermal shutdown, watchdog, over- and undervoltage condition switch all drivers in

sink condition. The microcontroller needs to clear the status bits to reactivate the drivers.

3.6

Overvoltage and undervoltage detection

If the power supply voltage VS rises above the overvoltage threshold VVS_OV

(typical 20 V / 30 V), all gate driver stages are switched in sink condition to protect the

H-bridge and the load, setting the OV flag. Two values for the overvoltage threshold can be

selected with the SPI. When the voltage VS drops below the undervoltage threshold

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