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DS20005595A-page 1

AT9919

Features

• Hysteretic Control with High-side Current Sensing

• Wide Input Voltage Range: 4.5V to 40V

• >90% Efficiency

• Typical ±5% LED Current Accuracy

• Up to 2 MHz Switching Frequency

• Adjustable Constant LED Current

• Analog or Pulse-With Modulation (PWM) Control

Signal for PWM Dimming

• Overtemperature Protection

• –40ºC to +125ºC Operating Temperature Range

Applications

• LED Lighting Applications

General Description

The AT9919 is a PWM controller IC designed to drive

high-brightness LEDs using a buck topology. It

operates from an input voltage of 4.5 VDC to 40 VDC

and employs hysteretic control with a high-side current

sense resistor to set the constant output current.

The operating frequency range can be set by selecting

the proper inductor. Operation at high switching

frequency is possible since the hysteretic control

maintains accuracy even at high frequencies. This

permits the use of small inductors and capacitors,

minimizing space and cost in the overall system.

LED brightness control is achieved with PWM dimming

from an analog or PWM input signal. Unique PWM

circuitry allows true constant color with a high dimming

range. The dimming frequency is programmed using a

single external capacitor.

The AT9919 comes in a small, 8-lead DFN package

and is qualified for LED lighting applications.

Package Type

8-lead DFN

(Top View)

See Table 2-1 for pin information.

8

1

2

3

4

7

6

5

CS

VIN

GATE

RAMP

ADIM

GND

VDD

DIM

GND

Hysteretic Buck High-Brightness LED Driver with High-Side Current Sensing