Document Number: MC33099

Rev. 6.0, 1/2007

Freescale Semiconductor

Technical Data

© Freescale Semiconductor, Inc., 2007. All rights reserved.

Adaptive Alternator Voltage

Regulator

The 33099 is designed to regulate the output voltage in diode-

rectified alternator charging systems common to automotive

applications. The 33099 provides either an analog or digital fixed

frequency duty cycle (ON/OFF ratio) control of an alternator’s field

current. Load Response Control (LRC) of the alternator field current

is accomplished by selecting the duty cycle for prevailing engine

conditions to eliminate engine speed hunting and vibrations caused

by abrupt torque loading of the engine owing to sudden electrical

loads being applied to the system at low engine RPM. Four LRC rates

are selectable by connecting pins 7 and 8 to ground.

The 33099 uses a feedback voltage to establish an alternator field

current that is in harmony with system load currents. The output

voltage is monitored by an internal voltage divider scheme and

compared to an internal voltage ramp referenced to a bandgap

voltage. This approach provides precision output voltage control over

a wide range of temperature, electrical loads, and engine RPM.

Features

• External High-Side MOSFET Control of a Ground-Referenced

Field Winding

• LRC Active During Initial Start

• <0.1 V Variation Over Engine Speeds of 2,000 to 10,000 RPM

• <0.2 V Variation Over 10% to 95% of Maximum Field Current

• Controlled MOSFET and Field Flyback Diode Recovery

Characteristics for Minimum RFI

• Pb-Free Packaging Designated by Suffix Code EG

Figure 1. 33099 Simplified Application Diagram

VOLTAGE REGULATOR

DW SUFFIX

EG SUFFIX (PB-FREE)

98ASB42567B

16-PIN SOICW

33099

ORDERING INFORMATION

Device

Temperature

Package

MC33099DW/R2

-40°C to 125°C

16 SOICW

MC33099CDW/R2

MCZ33099EG/R2

16 SOICW

(Pb-FREE)

MCZ33099CEG/R2

33099

FIELD

WINDING

IGNITION

SWITCH

CHASSIS

PHASE

GATE

SOURCE

PHASE FILTER

BAT

IGN

LAMP DRAIN

AGND

LRC1

LRC2

REMOTE

GND