L99LD01 datasheet(29/69 Pages) STMICROELECTRONICS

Nome de Peças	L99LD01

Descrição Electrónicos	High efficiency constant current LED driver for automotive applications

PDF	69 Pages

Scroll/Zoom	100%

Fabricante Electrônico	STMICROELECTRONICS [STMicroelectronics]

Página de início	http://www.st.com

Logo

29 / 69 page

DocID025319 Rev 3

29/69

L99LD01

Functional description

2.2.12

Input overvoltage programming

Supply overvoltage is programmed by the external partition ratio KI =R3/R4

According to the Figure 20 input overvoltage thresholds depend on the internal reference

voltages VOVTH1 and VOVTH2 (being VOVTH2 < VOVTH1)

Typical values of these internally generated references are 3.5 V and 3 V.

When the Battery voltage reaches a value in excess to VS_TH1 the converter is immediately

stopped. When the battery voltage, going down, reaches a value just lower to VS_TH2, the

converter restarts again.

Figure 20. Input overvoltage programming

Table 3. Suggested KL value and overvoltage thresholds

Number of LED

LED CHAIN nominal

DROP N*VF [V]

overvoltage VLED_OV [V]

1(1)

0.583

2(1)

0.292

3(1)

0.194

4(1)

0.146

0.117

0.097

0.083

0.073

0.065

54(2)

0.0583

60(2)

Not Applicable on boost converter topology, since the chain LED Drop must be always larger as the maximum battery

voltage.

Theoretical value; effective value will be clamped to 52 V (typ) by the OV protection.

L99LD01 Folha de dados(PDF) 29 Page - STMicroelectronics