908E625_10 Datasheet, PDF (37/49 Pages) Freescale Semiconductor, Inc – Integrated Quad Half H-Bridge with Power Supply, Embedded MCU, and LIN Serial Communication

FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
HIGH-SIDE OVERTEMPERATURE PROTECTION
The high-side output provides an overtemperature pre-
warning with the HTF in the Interrupt Flag Register. In order
to protect the output against overtemperature, the High-
Temperature Reset must be enabled. If this value is reached,
the part generates a reset and disables all power outputs.
HIGH-SIDE OVERCURRENT PROTECTION
The high-side output is protected against overcurrent. In
the event overcurrent limit is or was reached, the output
automatically switches off and the overcurrent flag is set.
Due to the high inrush current of bulbs, a special feature of
the 908E625 prevents an overcurrent shutdown during this
HS Current
HS Overcurrent Shutdown Threshold
inrush. If an PWM frequency is supplied to the FGEN output
during the switching on of a bulb, the inrush current is limited
to the overcurrent shutdown limit. This means if the current
reaches the overcurrent shutdown, the high side will be
switched off, but each rising edge on the FGEN input will
enable the driver again.
To distinguish between a shutdown due to an inrush
current or a real shutdown, the software must check if the
overcurrent status flag (HS_OCF) in the System Status
Register is set beyond a certain period of time. The
overcurrent status flag is cleared by writing a Logic [1] to the
HS_OCF in the System Status Register, see Figure 22.
t
FGEN Input
(MCU PWM
Signal)
t
Figure 22. Inrush Current Limiter on High-Side Output
SWITCHABLE VDD OUTPUT (HVDD)
The HVDD pin is a switchable VDD output pin. It can be
used for driving external circuitry that requires a V_DD voltage.
The output is enabled with bit PSON in the System Control
Register and can be switched on/off with bit HVDDON in the
Power Output Register. Low- or high-voltage conditions (LVI/
HVI) have no influence on this circuitry.
HVDD OVERTEMPERATURE PROTECTION
Overtemperature protection is enabled if the high-
temperature reset is enabled.
HVDD OVERCURRENT PROTECTION
The HVDD output is protected against overcurrent. In the
event the overcurrent limit is or was reached, the output
automatically switches off and the HVDD overcurrent flag in
the System Status Register is set.
Analog Integrated Circuit Device Data
Freescale Semiconductor
908E625
37