L9911

L9911 CAR ALTERNATOR MULTIFUNCTION SMART VOLTAGE REGULATOR PRELIMINARY DATA 1 ■ ■ ■ ■ ■ ■ ■ ■ ■ Features FULLY MONOLITHIC DESIGN HIGH SIDE FIELD DRIVER THERMAL PROTECTION FIELD SHORT CIRCUIT PROTECTION PROTECTED DIAGNOSTIC LAMP DRIVER PROTECTED HIGH SIDE RELAY DRIVER COMPLEX DIAGNOSTICS LOAD RESPONSE CONTROL DFM OUTPUT (FIELD MONITOR) Figure 1. Package Multiwatt8 Table 1. Order Codes Part Number L9911A L9911B Package Multiwatt8 Multiwatt8 Features See Table.9 See Table.9 2 Description The L9911 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. 3 Circuit Operation ance 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 capacitor (2.2µF) must be inserted between A+ and ground when using the device with very long cables. 3.2 PROTECTION It is present a protection against short circuits of the lamp and the relay power drivers (L) and of the field power driver (F+), a thermal drivers shutdown protection and an overvoltage protection of L power drivers. 3.3 DIAGNOSIS The circuit detects fault conditions related to the phase and F+ status and receives informations from one of the three alternator phases. In order to prevent spurious indications, fault warnings are not displayed immediately but are dalayed by a fixed time. 3.4 LOAD RESPONSE CONTROL The internal circuit regulates the soft start characteristics (activated always at engine start) and the soft attack characteristics. Rev. 3 1/15 The alternator's voltage regulator performs the following main functions: – 1) voltage regulation – 2) protection – 3) control fault diagnosis – 4) load response control 3.1 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 regulator is in fixed-frequency topology, the field switching frequency does not depend on 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 imped- November 2005 This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to change without notice. L9911 Figure 2. Pin Connection (Top view) 123456 78 P GND-case DFM RES. RES. L F+ B+ Table 2. Pin Descriptions N° 1 2 3 4 5 6 7 8 Pin P DFM RES. L GND-case RES. F+ B+ Phase sense input. Field monitor output. Reserved. Lamp terminal low side driver; relay terminal high side driver. Ground. Reserved. High side driver output. Sensed power supply. Function Table 3. Absolute Maximum Ratings (Tj = -40 to 150°C, unless otherwise specified) Symbol VS Parameter DC Supply Voltage (2 min. @ 25°C) Transient Supply Voltage (load dump) [see application circuit] t