33099

MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA

8

SYSTEM/APPLICATION INFORMATION

INTRODUCTION

The 33099 is specifically designed for regulation of an

automotive system voltage using diode-rectified alternator

charging systems commonly found in automotive applications.

The 33099 provides either an analog or digital duty cycle control

of an ON/OFF ratio of an alternator field current at a fixed

frequency. This provides for a Load Response Control (LRC) of

the alternator field current at low engine RPM to eliminate

engine speed hunting and vibration owing to abrupt torque

loading of the engine when a sudden electrical load is applied

to the system. Four LRC rates are selectable using a

combination of terminals 7 and 8 being connected to ground.

The 33099 provides a regulated voltage feedback system to

activate the alternator field current in response to system load

current. The output voltage is monitored by an internal voltage

divider scheme and compared to an internal voltage ramp

referenced to a bandgap voltage. The 33099 regulates the

system voltage to 14.8 V for the DW suffix and to 14.6 V for the

CDW suffix by generating a pulse width modulation (PWM)

voltage waveform at the GATE of an external MOSFET to

provide an average alternator field coil current as a function of

the internal voltage comparison.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com