33812 datasheet(12/25 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33812

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 VCC 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 VPWR 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.

VPWR) 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 VDS greater than the VIGNFB_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 Datasheet(PDF) 12 Page - Freescale Semiconductor, Inc

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