L99LD01 datasheet(23/69 Pages) STMICROELECTRONICS

Part #	L99LD01

Description	High efficiency constant current LED driver for automotive applications

PDF	69 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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23 / 69 page

DocID025319 Rev 3

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L99LD01

Functional description

Figure 12. Converter frequency range vs RSF and IRSF vs frequency

2.2.10

Start up LED overvoltage management

The following diagram shows the purpose of delay time windows “tDStart” and “tEnRecov”.

The first delay window tDStart has been thought to ensure an initial time period for charging

the external buffer capacitor of the charge pump C9. When VS is below VSMIN, the LED

overvoltage recovery bit is set. During this time interval, triggered as soon as the battery

voltage VS overcomes VSMIN threshold, the converter remain in a stop condition,

independently from PWM_L. When the tDStart is elapsed (typ. 5 ms), the converter is

released and behaves according to the PWM_L signal provided, that no failure occurs.

If no LED overvoltage comes during the 2nd time interval tEnRecov, LED ov recovery bit is

reset.

L99LD01 Datasheet(PDF) 23 Page - STMicroelectronics