l99h01 STMicroelectronics, l99h01 Datasheet - Page 29

• Manufacturer Part Number: l99h01
• Description: Motor Bridge Driver For Automotive Applications
• Manufacturer: STMicroelectronics

L99H01
3.4
3.5
3.6
3.7
Resistive low
The resistive output mode protects the L99H01 and the H-bridge in the standby mode and in
some failure modes (internal and external thermal shutdown (TSD)), charge pump low
(CP_LOW), stucked reset (STK_RESET_Q) and power-on reset (PORES)). When a gate
driver changes into the resistive 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).
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 is not change the state of the output drivers. On contrary, the over
load condition switches the corresponding halfbridge 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 driver in sink
condition. The microcontroler needs to clear the status bits to reactivate the drivers.
Overvoltage and undervoltage detection
If the power supply voltage V
(typical 20 V / 30 V), all gate driver stages are switched in sink condition to protect the
H-bridge and load. The OV bit is set. Two values for the overvoltage threshold can be
selected with the SPI. When the voltage V
V
to avoid the operation of the power devices without sufficient gate driving voltage (increased
power dissipation). The UV bit is set. If the supply voltage V
voltage the gate driver stages return to the programmed state. If the under- and overvoltage
recovery disable bit (OV_UV_RD) is set, the automatic turn-on of the drivers is deactivated.
The microcontroller needs to clear the status bits to reactivate the drivers.
Charge pump
The charge pump uses 2 external capacitors. The output of the charge pump has a current
limitation. In standby mode and after a thermal shutdown has been triggered the charge
pump is disabled. If the charge pump output voltage remains too low for longer than T
gate drivers are switched-off (resistive output, see
cleared through a software reset to reactivate the gate drivers.
VSUVH
-V
VSOVH
(UV switch-off voltage), all gate driver stages are switched in sink condition
S
Doc ID 15567 Rev 3
rises above the overvoltage threshold V
S
drops below the undervoltage threshold
Section
3.4). The CP_LOW bit has to be
S
recovers to normal operating
VSOVH
CP
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