Datasheet

© 2012 Fairchild Semiconductor Corporation 3 FEBFL7701_L30U003A • Rev. 1.0.2
This user guide supports the Evaluation kit for the FL7701. It should be used in
conjunction with the FL7701 datasheet as well as Fairchild’s application notes and
technical support team. Please visit Fairchild’s website at www.fairchildsemi.com
.
1. Introduction
This document describes the proposed solution for a universal-input 2.4W LED ballast
using the FL7701. The input voltage range is 90V
RMS
– 265V
RMS
and there is one DC
output with a constant current of 85mA at 28V
MAX
. This document contains general
description of FL7701, the power supply specification, schematic, bill of materials, and
the typical operating characteristics.
1.1. General Description
The FL7701 LED lamp driver is a simple IC with PFC function. The special “adopted
digital” technique automatically detects input voltage condition and sends an internal
reference signal, resulting in high power factor. When an AC input voltage is applied to
the IC, the PFC function is automatically enabled. Otherwise, when a DC input is applied
to the IC, the PFC function is automatically disabled. The FL7701 does not require a bulk
capacitor (electrolytic capacitor) for supply rail stability, which can significantly affect
LED reliability.
1.2. Key Features
 Digitally Implemented Active PFC Function
 Built-in Self-Biasing HV Startup Circuit
 Application Input Range: 80V
AC
~ 308V
AC
 AOCP Function with Auto-Restart Mode
 Built-in Over-Temperature Protection
 Cycle-by-Cycle Current Limit
 Current-Sense Pin Open Protection
 Low Operating Current: 0.85mA (Typical)
 Under-Voltage Lockout with 5V Hysteresis
 Programmable Oscillator Frequency
 Programmable LED Current
 Analog Dimming Function
 Fixed Soft-Start Function
 Precise Internal Reference: ±3%