AP3720_13 Datasheet, PDF (1/13 Pages) BCD Semiconductor Manufacturing Limited – CURRENT MODE PWM CONTROLLER FOR BJT

Preliminary Datasheet
CURRENT MODE PWM CONTROLLER FOR BJT
AP3720
General Description
Features
The AP3720 is a low startup current, current mode
PWM controller with green-mode operation. The
PWM switching frequency at normal operation is 65k,
but when the output power drops below the
specifically level, the device enters the
frequency-drop mode and the typical operating
frequency is 20kHz (no audible noise). Additionally,
when the load drops to a very low level or zero, the
IC operates in so called ‘burst mode’ to minimize
switching loss.
The IC integrated a lot of functions such as the
Lead-Edge Blanking (LEB) of the current sensing,
internal slope compensation, line compensation, and
several protection features. The protection functions
include cycle-by-cycle current limit (OCP), VCC
over voltage protection (OVP), OTP and OLP.
The AP3720 is available in DIP-8 and SOIC-8
packages.
• Low Startup Current (2.5µA) and Low
Operating Current (1.2mA)
• Off-line Converter Applied in Sub 25W Range
• Skip Cycle Mode Achieves Low Standby Power
(<200mW)
• Cycle-by-Cycle Power Limited
• Frequency-drop Mode
• Soft Start with 2ms
• Programmable Drive Current for BJT
• Leading Edge Blanking
• Pre-shutdown Decreases Turn-off Losses
• Reliable Protection:
Accurate OCP with Line Compensation
Short Circuit Protection
Over Voltage Protection for VCC
Hysteretic Thermal Shutdown Protection
Applications
• STB
• Cable Modem
• ADSL Modem
• DVD Recorder
Jan. 2013 Rev. 1. 1
DIP-8
SOIC-8
Figure 1. Package Types of AP3720
BCD Semiconductor Manufacturing Limited
1