Rev. 1.20

2

March 12, 2013

HT7L4091

Block Diagram

LDO

Blank

OTP

R

S

Q

PWMD

0.25V

CS

PDM

VIN

GDR

GND

25V

VDD

RT

0.5V

QB

R

S

Q

QB

LD

100k

OSC

(jitter)

Power On

Reset

UVLO

ON

Pin Assignment

VIN

CS

GND

GDR

RT

LD

VDD

PDM

HT7L4091

8 SOP-A

1

2

3

4

8

7

6

5

Pin Description

Pin Name

I/O

Description

VIN

I

Input voltage pin

CS

I

LED string current sense input

GND

—

Power ground

GDR

O

Gate driver for the external MOSFET

PDM

I

PWM dimming pin

Also functions as enable input pin.

VDD

O

Positive Power supply

Used for the internal circuits except the gate driver circuit. A 0.1μF capacitor must be

connected between the VDD and the GND pins.

LD

I

Linear dimming pin

Set the current sense threshold as long as the voltage on this pin is less than 250mV (typ.).

RT

I

Oscillator control pin

A resistor is connected between the RT and the GND pins to set the off-time.