Introduction - Infineon EZ-PD PAG2S-2P User Manual

EZ-PD™ PAG2S-2P 65 W high-frequency active clamp flyback
charger and adapter solution user guide

Introduction

1 Introduction
The Active Clamp Flyback (ACF) converter is a popular flyback topology that offers ZVS for the FETs. This topology
is suitable for higher frequency operation than the QR flyback because of the ZVS operation. There is also a
complete energy recovery in transformer leakage inductance, which is dissipated in the QR flyback RCD clamp.
ACF also has good electromagnetic interference (EMI) performance regarding ZVS operation and clamping of the
primary FET voltage through the clamp capacitor.
There are two types of ACF control modes: Complementary (CP) and noncomplementary (NCP). In the CP mode,
the main flyback and clamp switches are turned on/off alternatively to complement each other in every switching
cycle, and the transformer current waveform is sinusoidal. Both the main flyback and clamp switches are under
ZVS switching. In the CP mode, the switching frequency rises with load decrease. This may have an impact on
light load and standby efficiency as well as EMI. Additionally, the full resonant current in the resonant tank
increases the conduction loss in the transformer.
To overcome the increased conduction loss and improve the light-load efficiency, use the noncomplementary
mode. This mode operates the active clamp FET so that it only turns on to accumulate enough magnetic energy
to ensure the main FET ZVS operation. This way, the circulating clamp capacitor currents are mitigated to output.
A few analog ACF controllers exist in the market. Some of them can only support either CP or NCP, but not both
types of operation.
Full-bridge
Rectifier
EMI
Filter
Primary Side
Figure 1 High-level block diagram of EZ-PD™ PAG2S-2P REF_65W_HFACF_PAG2 Solution
Infineon provides a comprehensive solution for ACF-based flyback adapters. Specifically, for AC-DC conversion,
Infineon's EZ-PD™ PAG2x-based solution offers two chip solutions:
EZ-PD™ PAG2P primary side startup controller with high and low side PWM drive
•
EZ-PD™ PAG2S USB PD power adapter secondary side controller with synchronous rectification (SR)
•
EZ-PD™ PAG2S-2P based 65W active clamp flyback charger and adapter demonstrates this highly efficient
topology.
User guide
Vbst
VCC
GD
GD
GDH Driver
SW
VCC
PULSEIN
EZ-PD
RT PAG2P
SS
HV
VBU S_IN
SR_DRAIN
CC_COMP_GPIO
EZ-PD PAG2S
EA_OUT
FB
PWM_DRV
GPIO
Temperature
Sensor
Secondary Side
3
VBU S_TypeC
CC1
CC2
DP_GPIO
DM_GPIO
002-39511 Rev. **
2024-02-15