AP3720_13 Datasheet, PDF (2/13 Pages) BCD Semiconductor Manufacturing Limited – CURRENT MODE PWM CONTROLLER FOR BJT

Preliminary Datasheet
CURRENT MODE PWM CONTROLLER FOR BJT
AP3720
Pin Configuration
P Package
(DIP-8)
M Package
(SOIC-8)
LINE 1
NC 2
FB 3
BIAS 4
8 CS
7 GND
6 DRV
5 VCC
LINE ₁
NC 2
FB 3
BIAS 4
8 CS
7 GND
6 DRV
5 ^VCC
Figure 2. Pin Configuration of AP3720 (Top View)
Pin Description
Pin Number Pin Name
Function
1
LINE Line compensation for OLP
2
NC
No connection
Connect opto-coupler to this pin. The voltage of FB controls the mode
3
FB
of operation in one of the three modes: burst mode, frequency-drop
mode (20kHz) and normal mode (65kHz). When the voltage of FB
reaches a limit-point, the system enters the OLP mode
4
BIAS
This pin sets the driver current inside AP3720 with an external resistor
to GND
This pin is the positive supply voltage input. During start up, the
5
VCC
power is supplied from line voltage. When V_CC reaches 20V, the
system begins running and the power is supplied from the auxiliary
transformer winding
6
DRV This pin supplies the drive current for the external power NPN switch
7
GND This pin is the control ground
This pin senses the primary current and routes it to internal
8
CS
comparator. By changing the value of the sense resistor, the primary
peak current set point is adjusted according to the output power
demand
Jan. 2013 Rev. 1. 1
BCD Semiconductor Manufacturing Limited
2