Diodes Incorporated

AP3720 (Not Recommended for new design)

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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 cal°C ‘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.


  • 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


  • STB
  • Cable Modem
  • ADSL Modem
  • DVD Recorder

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Product Parameters

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Product Change Notices (PCNs)

A PCN may only apply to specific orderable part numbers in this datasheet. Please refer to the corresponding PCN to see the exact orderable part number(s) affected.

PCN # Issue Date Implementation Date Subject
PCN-2401 2019-01-30 2019-07-30 Device End of Life (EOL)