Ap5725, White led step-up converter, Pin descriptions – Diodes AP5725 User Manual
Page 2: Functional block diagram
AP5725
WHITE LED STEP-UP CONVERTER
AP5725
Document number: DS31844 Rev. 3 - 2
2 of 17
July 2010
© Diodes Incorporated
Pin Descriptions
Pin Name
Description
SW
Switch Pin. Connect inductor/diode here. Minimize trace area at this pin to reduce EMI.
GND GND
pin.
FB
Feedback Pin. Reference voltage is 0.25V. Connect cathode of lowest LED and a sense
resister here. Calculate resistor value according to the formula: R
SET
= 0.25V / ILED
EN
Converter On/Off Control Input. A high input at EN turns the converter On, and a low input
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
IN
Input Supply Pin. Must be locally bypassed with 1
μF or 2.2μF to reduce input noise.
Functional Block Diagram
1.2MHz
Oscillator
RAMP
Generator
Σ
-
+
-
+
-
+
V
REF
0.25V
VIN
3
FB
Rc
Cc
Comparator
A2
CONTROL
LOGIC
A1
1
Driver
SW
Q1
2 GND
4
EN
Enable
6
OTP
5
OVP