PROTECTION

Darlingtyon

Thermal

Shutdown

Threshold

150

°C

(pin 10) Zener Voltage

6

6.2

8

8.2

V

V

Overvoltage Protection

Threshold (7)

°C

–30

25

23

32

38

40

V

V

Lamp Driver Circuit Current

300

1500

mA

Pin 13 Dump Sustaining Capapility

Current

°C

200

mA

Zener Clamping Voltage

t = < 3ms

110

V

t = < 6ms, full T

°C

100

90

V

V

Notes : 1. d = 50 % the duty cycle of the output signal at pin 6.

3. Measured 100 ms after turn-on.

6. The lamp is switched on when the cable A is broken (IC without power voltage supply).

CIRCUIT OPERATION

The L585 alternator regulator performs two main functions : regulation control and fault diagnostics.

REGULATION

The alternator voltage is compared with a reference

voltagein an error amplifier (see block diagram), the

output of which determines the duty cycle of the ex-

ternal darlington. This darlington switches the cur-

rent in the excitation coil of the alternator.

The switching frequencyis fixed and is set by the ex-

pacitive positive feedback and a monostable elimi-

natesspurious switching caused by contact bounce.

The basecurrent deliveredto the external darlington

must be dimensioned according to the charac-

teristics of this darlington and the maximum coil cur-

rent.

DIAGNOSTIC

This circuit receives informationfrom the battery,the

alternator and one alternator phase. It indicates

anomolousconditions by driving a 3 W lamp. To pre-

vent spurious fault warnings some indications are

not displayed immediately but are delayed by a fixed

time. No external components are needed to imple-

ment this delay since it is produced internally by di-

viding the internal oscillator with an eight-stage di-

vider to give a delay of 128 periods. For a one sec-

ond delay the oscillator frequency must be 128 Hz.

The lamp is driven after a delay when the following

conditions occur : no charge, break or short circuit

in the alternator sense wire.

The diagnostic lamp is driven immediately when the

cable connecting the alternator to the battery is bro-

ken (Va-Vbatt above 2.6 typ.) or when the IC is with-

typ. in this case).

ELECTRICAL CHARACTERISTICS (continued)

Symbol

Parameter

Test Conditions

Min.

Typ.

Max.

Unit

L585

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