Advance Information
ALTERNATOR VOLTAGE REGULATOR

The MC33099 is specifically designed for regulation of an automotive system voltage using diode rectified alternator charging systems commonly found in automotive applications. The MC33099 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 due 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 Pins 7 and 8 being connected to ground.

•Provides High Side MOSFET Control of a Ground Referenced Field Winding
•Forced Load Response Control (LRC) at Low Engine RPM Due to Abrupt System Load Currents
•Four User Programmable LRC Rates From 1.8 Seconds to 7.4 Seconds
•LRC Response During Initial Start
•Regulation Voltage Range is ±0.1V at a 14.8 V Regulation Voltage @ 25°C
•<0.1 V Variation Over Engine Speed Range From 2000 to 10,000 RPM
•<0.2 V Variation Over 10% to 95% of Maximum Alternator Field Current
•Minimum Duty Cycle of 3.1% for System Load Currents as Low as 1.0 A.
•PWM Fixed Operating Frequency of 395 Hz
•Internal Level Shifting of External System Voltages
•Internal Lamp Driver with Short Circuit, Current Limit, Thermal Limit and Load Dump Protection
•Fault Protection for a Field Short to Ground
•Load Dump Protection of Lamp Driver, Field Control Devices, and Loads
•Fault Detection of Undervoltage, Overvoltage, Phase Loss (Lose or Broken Belt) and High Remote Sense Resistance (lose or corroded sense wire)
•Controlled MOSFET and Field Flyback Diode Recovery Characteristics for Minimum RFI
•<1.5 mA Standby Current From Battery @ 25°C
•<2.5 mA Standby Current From Battery @125°C