ACE714
High Efficiency Low Noise PFM Step-up DC/DC Converter
Description
The ACE714 veriable frequency step-up Converter drives white LEDs with a constant current to provide
backlight in cell phones, PDAs, and other handheld devices. It features allowing series connection of the
white LEDs so that the LED currents are identical for uniform brightness. An enable input can be pulsed
repeatedly to adjust LEDs brightness. The fast 3MHz operation frequency allows for smaller capacitor
and inductor. Fault condition protection uses cycle-by cycle current limiting to sense maximum inductor
current and over-voltage protection. The 0.2V low reference voltage minimized the power loss across the
current sense resistor.
The converter can operate from 2V to 6V, and capable of delivering maximum 200mA output current at
4-LEDs application with 3V input voltage is as low as 120uA. All of these features make ACE714 be
suitable for the portable devices, which are supplied by a single battery.
Features
Up to 24V Output Voltage
Wide Operation Range: 2V to 6V
Maximum 3MHz Operating Frequency
PWM Dimming Control
Shutdown Current <1uA
Current Limit Cycle-by-Cycle
Low Current Sense Threshold: 200mV
24V Over Output Voltage Protection
Application
Compact Back Light Module
Power Source for LED
Constant Current Source
Typical Application
L1
Vin
10uH
D1
SS14
LED 1
LED 17
LED2
+
Cin
4.7uF
+
Cout
4.7uF
LED 18
LED 3
LED 19
ON
OFF
Vin
LX
ACE714
OVP
CE
FB
GND
LED 4
R1
LED 20
R5
Figure 1. ACE714 Typical Application Circuit
VER 1.3
1
ACE [ ACE TECHNOLOGY CO., LTD. ]
