HT7L4091 datasheet(11/26 Pages) HOLTEK

11 / 26 page

Rev. 1.00

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Rev. 1.00

��i� �� 011

HT7L4091

Universal Step-Down PWM Control

For High Brightness LED Lighting Control

Enhanced Short Circuit Protection

When most LEDs are shorted in the application circuit, the current regulation may lose control

resulting in the current increasing to an extremely high level. When the current is more than twice

of the set Ipeak, resulting from externally shorted LEDs, the device will shut down gate driving

operations.

The operation state is shown in the accompanying figure. When the circuit is operating normally,

VCS can be limited to VCS-TH, while some LEDs are shorted, the LED current is still limited and the

output voltage is adjusted to meet the current requirement. If the circuit encounters a serious short,

the voltage increase of (current) in TBlank would be larger than the decrease in TOFF, VCS will exceed

VCS-TH and reach VCS-Short. The HT7L4091 will then shut down the gate driver until UVLO resets the

HT7L4091.

TB�ank TOff

VCS-TH

VCS-Sho�t

Normal

Slight

Short

Serious

Short

Shut Down

VCS

GDR

Vin

GND

VDD

PDM

Rlim

RCS

Clim

CVDD

Cin

HT7L4091 Datasheet(PDF) 11 Page - Holtek Semiconductor Inc