Car Alternator Voltage Regulator

  The L9407F is a monolithic multifunction alternator Voltage Regulator intended for use in Automotive application. It includes the control section, the field power stage, fault diagnostic circuit which drives a warning lamp, and the protection against short Circuits CIRCUIT OPERATION The alternator's Voltage Regulator performs the following main functions: ? 1) voltage regulation ? 2) protection ? 3) control fault diagnosis ? 4) load response control VOLTAGE REGULATION The alternator voltage is compared with a reference voltage in an amplifier, whose output determines the switching frequency of output power MOS whose current excites the coil of the alternator; as the Regulators are a self-oscillating type this frequency depends on the whole system parameter set including the alternator characteristics. The Regulators have an integrated Filter in the voltage sensing path guaranteeing the correct behaviour of the devices also when the Rectifier Diodes feature very high switching spikes. The internal filtering allows the usage of the device also with very long cables connecting the alternator to the Battery with an impedance so high to cause a superimposed ripple on the alternator voltage higher than 5-6V. Consequently it doesn't need, in the standard application, any external component. Anyway an external application (2.2uF or 2.7uF) must be inserted between A+ and ground when using the device with very long cables. PROTECTION It is present a protection against short Circuits of the lamp and the RELAY Power Drivers (D+) and of the field Power Driver (DF), a thermal drivers shutdown protection and an overvoltage protection of D+ Power Drivers DIAGNOSIS The circuit detects fault conditions related to the phase and DF status and receives informations from one of
Item: L9407F
File Size : 15 KB
Pages : 11 Pages

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