33812 Datasheet, PDF (12/25 Pages) Freescale Semiconductor, Inc – SMALL ENGINE CONTROL IC

FUNCTIONAL DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
FUNCTIONAL DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
SUPPLY INPUT (VPWR)
The VPWR pin is battery input to the 33812 IC. A POR/LVI
sub-circuit monitors this input's voltage level. The VPWR pin
requires external reverse battery and transient protection.
OUTPUT (VCCREF)
The VCCREF output pin is used to drive an external 5.0 V
regulator PNP bipolar pass transistor.
INPUT (VCCSENS)
The VCCSENS pin is used to monitor the +5.0 Volts from
the external pass transistor’s output. A POR will be
performed when the voltage on the VCCSENS pin goes from
0 to VCC.
DIGITAL GROUND (DGND)
The DGND pin provides ground reference for the digital
inputs and outputs. The V_CC supply is referenced to the
DGND pin.
PGND1 AND PGND2
The PGNDx pins provide power additional ground
reference for the power outputs, ROUT, LAMPOUT, and
INJOUT. The V_PWR supply is referenced to the PGND pins.
INJECTOR INPUT (INJIN)
The INJIN pin is the parallel input that controls the Injector
output, INJOUT. The INJIN pin is a logic level input with built-
in pull-down to ground to prevent accidental actuation of the
injector if the connection to the pin is lost.
INJECTOR AND RELAY DRIVER OUTPUT (INJOUT/
ROUT)
The INJOUT and ROUT output pin are the Injector driver
and Relay driver outputs for the fuel Injector and Relay that
this IC supports. The Relay Driver and Injector Drivers are
identical in operation and features The Injector driver output
is controlled by the parallel input (INJIN) and the Relay driver
output is controlled by the parallel input (RIN). The Injector
and Relay outputs are turned off during VPWR over-voltage
and under-voltage events. Open circuit (during off state),
short to battery (during on state), and over-temperature faults
are detected and annunciated as a logic high on the INJFLT
and RELFLT lines. Over-current is limited by the current
limiting circuitry but is not annunciated unless the over-
current is due to a short to battery. For either driver, when a
fault condition is detected, the driver will turn off, and when
the fault condition clears, it will try to turn on again, if the input
line goes low and then high.
LAMP DRIVER OUTPUT (LAMPOUT)
The LAMPOUT output pin is the lamp driver, a low side
driver capable of driving an incandescent lamp. The current
limit blanking time is set to allow the driver to handle the
inrush current of a cold lamp filament. The LAMPOUT output
is controlled by the parallel input pin (LAMPIN). The
LAMPOUT low side driver is protected against over-
temperature, and short to battery. Unlike the Injector driver,
when a fault condition is detected, the LAMPOUT driver will
turn off, but when the fault condition clears, it will to turn on
again, while the input line, LAMPIN is high.
PRE-DRIVER OUTPUT, WITH FEEDBACK AND
SUPPLY VOLTAGE INPUT (IGNSUP, IGNOUTL,
IGNOUTH, IGNFB)
The IGNOUTL and IGNOUTH output pins are the low side
and high side output pins of the Ignition pre-driver. They are
used to drive either an IGBT or a Darlington BJT to control the
ignition coil current to produce a spark. The choice of output
device, IGBT or Darlington Bipolar Junction Transistor, is
indicated by the choice of supply voltage on the IGNSUP pin.
When driving a Darlington bipolar transistor, the IGNSUP
line must be tied to the +5.0 V supply. When driving an IGBT,
the IGNSUP may be tied to a protected voltage source (e.g.
V_PWR) greater than +5.0 V to achieve the necessary gate
drive voltage required by the IGBT. The high side output
device will current limit if the circuit is forced to supply
currents greater than the maximum indicated.
The IGNOUTL and IGNOUTH lines are controlled by the
parallel input (IGNIN).The IGNOUT(L,H) outputs and the
associated feedback pin, IGNFB, provide short to battery
protection for the external driver transistor. A 10:1 voltage
divider must be used on the feedback pin to prevent >400
Volt Ignition Coil flyback voltage from damaging the IC.
Open circuit (off state), short to battery (on state), and
temperature limit threshold exceeded on the pre-driver stage
are detected on the output, and all annunciated as a logic
high on the IGNFLT line.
There is no individual annunciation of these three fault
conditions. The IGNFLT line goes high when any of the three
fault conditions are present.
If an over-current /short to battery fault condition, as
defined by a V_DS greater than the V_{IGNFB_OUT(FLT-TH)} is
detected, the IGNOUTH or IGNOUTL will turn off and not turn
on again until the fault condition has cleared and the IGNIN
input line goes low and then high.
OUTPUTS (INJFLT, RELFLT, IGNFLT)
The INJFLT, RELFLT and IGNFLT pins are the logic level
outputs that indicate when a fault condition has been
detected on the INJOUT, ROUT or IGNOUT pins. These pins
33812
12
Analog Integrated Circuit Device Data
Freescale Semiconductor