L9409 datasheet(8/13 Pages) STMICROELECTRONICS

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Device description

L9409

8/13

Doc ID 022665 Rev 2

4.2

Load response control (LRC)

4.2.1

Description

This function controls the sudden torque increase on engine when the last is started or

electric load is changed within the idling speed. In particular, the alternator output current is

increased gradually at a constant rate (LRCrate) when generating is started. The time

needed to rump up from 0% to 100% of duty cycle is defined as TLRC_rate. This function is

enabled when the alternator achieves a certain speed (fLRC_EN) and after a delay time

(TLRC_delay). TLRC_delay is defined as the period from Nalt attainment to the start of

generating as described in Figure 4. The LRC is disabled while the alternator rotor speed is

greater than a set value (fLRC_DIS).

Figure 4.

LRC function

4.2.2

Electrical characteristics

Tj = -40 to 150 °C, unless otherwise specified.

Table 7.

Electrical characteristics

Symbol

Parameter

Test condition

Min.

Typ.

Max.

Unit

fLRC_EN

LRC enable frequency

LRC enabled above this

frequency

130

145

160

fLRC_DIS

LRC transition frequency

LRC disabled above this value

270

300

330

TLRC_delay Load response control delay

delay of activation of LRC

2.1

3.5

TLRC_rate Load response control rate

(1)

-2.1

2.9

This is the time duration that L9460 takes to ramp up from 0% to 100% duty cycle in response to an increased load on the

generator.

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