AP5726
WHITE LED STEP-UP CONVERTER
Description Pin Assignments
(Top View)
The AP5726 is a step-up DC/DC converter specifically
designed to drive white LEDs with a constant current. The
1 6 VIN (Top View)
SW
device can drive 2 ~ 6 LEDs in series from a Li-Ion cell.
Series connection of the LEDs provides identical LED
SW 1 6 GND
currents resulting in uniform brightness and eliminates the GND 2 5
OVP
need for ballast resistors. For driving higher number of LEDs, 2 5
V FB
IN
AP5726 also supports a single feedback of parallel
74
FB 3
EN
3 4
OVP EN
connected multiple strings of equal number of LEDs.
SOT26 / TSOT23-6
DFN2020C-6
The AP5726 switches at 1.2MHz that allows the use of tiny
external components. A low 0.31V feedback voltage
minimizes power loss in the current setting resistor for better
efficiency.
Features Applications
High efficiency: 84% typical Cellular Phones
Fast 1.2MHz switching frequency PDAs, Hand help Computers
Current limit and UVLO protections Digital Cameras
Internal Thermal Shutdown MP3 Players
Internal Over Voltage Protection GPS Receivers
Integrated soft-start function
SOT26, TSOT23-6 and DFN2020C-6: Available in
Green Molding Compound (No Br, Sb)
Lead Free Finish/ RoHS Compliant (Note 1)
Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
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AP5726
WHITE LED STEP-UP CONVERTER
Pin Descriptions
Pin Name Description
SW Switch Pin. Connect inductor/diode here. Minimize trace area at this pin to reduce EMI.
GND GND pin.
Feedback Pin. Reference voltage is 0.31V. Connect cathode of lowest LED and a sense
FB
resister here. Calculate resistor value according to the formula: R = 0.31V / ILED
SET
Converter On/Off Control Input. A high input at EN turns the converter On, and a low input
EN turns it off. If On/Off control is not needed, connect EN to the input source for automatic
startup. The EN pin cannot be left floating.
OVP Output Voltage detect pin for over voltage protection.
V Input Supply Pin. Must be locally bypassed with 1 F or 2.2 F to reduce input noise.
IN
Functional Block Diagram
OVP
5
1 SW
Comparator
Driver
A2 Q1
CONTROL
LOGIC
Rc
OTP
A1
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Cc
FB
3
V
REF
V
6
IN
0.31V
RAMP
Generator
2 GND
4 Enable
EN
1.2MHz
Oscillator
2 of 17 July 2010
AP5726
Diodes Incorporated
www.diodes.com
Document number: DS31845 Rev. 3 - 2
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