mc33812 Freescale Semiconductor, Inc, mc33812 Datasheet - Page 16

• Manufacturer Part Number: mc33812
• Description: Multifunctional Ignition And Injector Driver
• Manufacturer: Freescale Semiconductor, Inc

controlled by the logic level RIN input pin. When RIN is high,
the ROUT pin is pulled to ground, turning on an external relay
or other device. When RIN is low, the relay coil pulls the
ROUT output to V
and it’s output device is protected against over-current, short
to battery, over-temperature, inductive flyback over-voltage
and VPWR over-voltage.
the Injector driver and can be used as a second Injector
driver, for two cylinder applications, as long as maximum
power dissipation considerations are observed.
ROUT PROTECTION FEATURES
Over-current (I
protection schemes to prevent damage to the output device.
current event occurs. In this case, the current limiting circuitry
will attempt to limit the maximum current flow to the specified
I
Short to Battery
current fault is due to a hard short to battery. In this case, the
protection circuitry will, after the short detection filter time,
turn off the output driver. The output will not try to turn on
again until the RIN input goes low and then high again.
RELFLT line.
Temperature Limit (T
temperature of the output device. Any time the maximum
temperature limit on the output device is exceeded (
device will shutdown until the junction temperature falls below
this maximum temperature minus the hysteresis temperature
value. The
controls the output device regardless of the state of the RIN
input. The device is unable to be activated until the junction
temperature falls below this maximum temperature minus the
hysteresis temperature value.
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33812
FUNCTIONAL DEVICE OPERATION
RELAY DRIVER OPERATION
OUT LIM-REL
The Relay Driver (ROUT) is a low side driver that is
The ROUT driver includes off state open load detection
The Relay Driver is functionally and electrically identical to
The ROUT Driver protection scheme uses three separate
The first protection scheme is deployed when an over-
The second protection scheme is invoked when the over-
A short to battery is reported as a high logic level on the
The third protection scheme deals with the junction
The maximum temperature (
T
value.
LIM
OUT-LIM ROUT
hysteresis value is T
BAT
, and the relay is turned off.
LIM
)
)
T
LIM
) protection scheme
LIM(HYST)
.
RELAY DRIVER OPERATION
T
LIM
), the
level on the RELFLT line.
Over-voltage (V
over-voltage conditions:
the ROUT output turns off and stays off until the over-voltage
condition abates and the RN input pin toggles low and then
high again.
voltages greater than V
network that limits the voltage across the output device to
V
ROUT FAULT DETECTION FEATURES
Off State, Open Load Detection
level on the drain of the output device in the off state. Internal
to the device is a pull-down current source. In the event of an
open injector the drain voltage is pulled low. When the
voltage crosses the open load detection threshold, an open
load is detected. The open load fault detect threshold is set
internally and is not programmable. The open load fault is
reported as a high logic level on the RELFLT line.
On State, Shorted Load Detection
(short to battery) in the on state. A shorted load fault is
reported when the drain pin voltage is greater than the preset
short threshold voltage. The shorted load fault detect
threshold is set internally and is not programmable. The
shorted load fault is reported as a high logic level on the
RELFLT line.
Clearing the RELFLT line
reasons, while the RIN line is high (on state):
a low logic level and the returns high (rising edge).
CLAMP-REL
An over-temperature fault is also reported as a high logic
The relay driver is also protected against two types of
When the VPWR supply exceeds the V
The output device is protected against inductive flyback
An open load on the relay driver is detected by the voltage
The ROUT driver is capable of detecting a shorted load
When the RELFLT line goes high for any of the following
• Short to battery
• Over-temperature
• Over-voltage
• Open load
The RELFLT line will remain high until the RIN line goes to
volts.
CLAMP-REL
Analog Integrated Circuit Device Data
CLAMP-REL
and V
PWR(OV)
by an active clamping
Freescale Semiconductor
PWR(OV)
)
threshold,