Hysteretic Buck High-Brightness LED Driver with High-Side Current Sensing
• 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
• LED Lighting Applications
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.
See Table 2-1 for pin information.
2016 Microchip Technology Inc.