ST L9409 User Manual

L9409

Alternator voltage regulator with load response control

Features

■IC regulator for 12 V type alternator

■Fixed frequency regulation loop

■130 mΩ high side field driver

■Fail safe device with double sensing of battery voltage (VB and VS)

■Load response control (LRC) function activates after an initial time delay

■Self start function from phase frequency

■“Z” shaped regulation curve compliant with VW specification.

■Key recognition from L input

■Field driver, lamp driver and relay driver short protection

■Complex diagnostics

■Thermal shutdown at 175 °C

Description

The L9409 is a monolithic multifunction alternator voltage regulator intended for use in automotive applications.

The device regulates the output of an automotive generator by controlling the field winding current by means of either an analog fixed frequency PWM signal or digital fixed frequency PWM signal (LRC). The Load Response Control function is activated in order to eliminate IC engine speed fluctuation and vibrations caused by the insertion

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Multiwatt8

of sudden electrical loads during alternator low speed operations (f < 310 Hz). Both the analog and digital duty cycle are applied to a high side driver.

The device is able to regulate the voltage either using a feedback signal from B pin or from S pin depending on application needs. S pin is intended to have a clear direct connection with the positive terminal of the car battery. If this connection gets lost the device will regulate voltage using B pin giving a fail safe functionality.

Using L pin is possible to sense key switch and a pre-excitation duty cycle is applied on the field coil in order to start phase voltage sensing. In the case L connection gets lost, device starts to generate using residual magnetism of the generator.

Field, lamp and relay drivers are protected against short circuit.

Order codes

Table 1. Device summary

Order code	Junction temp range, °C	Package	Packing
L9409F	-40 to 150	Multiwatt8	Tube

January 2012

Doc ID 022665 Rev 1

1/13

www.st.com

Contents	L9409

Contents

1	Block and application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		3
2	Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		4
3	Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		5
	3.1	Voltage maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	5
	3.2	Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	5
4	Device description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		6
	4.1	Voltage regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	6

4.1.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1.2 Electrical characteristic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4.2 Load response control (LRC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.2.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2.2 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.3 Lamp and relay driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.3.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.3.2 Electrical characteristic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.3.3 Relay driver description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.3.4 Electrical characteristic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.4 Protection and diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

	4.4.1	Diagnostic electric parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	10
5	Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		11
6	Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		12

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L9409	Block and application diagram

1 Block and application diagram

Figure 1. Block and application diagram

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		3
	*$3*36

Doc ID 022665 Rev 1

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Pin description	L9409

2 Pin description

Figure 2.

Multiwatt8 pin connection diagram

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3

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,

2

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4AB CONNECTED TOEPINT

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Table 2.

Pin description

Pin #

Pin name

Function

1

P

Phase input

2

FM

Field monitor output

3

R

Relay terminal high side driver

4

L

Lamp terminal low side driver

5

G

Power ground

6

S

Battery sense input

7

F+

Field high side driver output

8

B

Voltage supply and generator output sense

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