AP3306

Document number: DS42803 Rev. 6 - 2

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www.diodes.com

May 2022

© Diodes Incorporated

AP3306

Operation Description

Diodes Incorporated

’s Smart Active Clamp Control Strategy: Valley Switching & Zero Voltage Switch (ZVS) Multiple Operation Modes.

The AP3306

’s patented control strategy allows the Active Clamp Fly-back system to operate on valley switching or ZVS according to the input

voltage. When operating under low line input, the valley switching can naturally achieve ZVS and the leakage inductance energy will be

transferred to output through the high side PMOSFET and CSN. When operating under high line input, the ZVS mode activated with perfect jitter

whilst balancing system efficiency and EMI performance. The ZVS with jitter operation is regarded as a quasi-soft switching technology, which

always turns on the primary PMOSFET at the peak status of the Drain-to-Source voltage (VDS) and uses leakage inductance to achieve ZVS with

jitter.

Available
Peak status to turn on

the PMOSFET

VDS of NMOS

GDL

GDH

ON

ON

Jitter

Figure 3. ZVS with Jitter Operation

PMOS Driving

Figure 4 shows the AP3306

’s easily built-in PMOS control method. The GDH pin connects to the PMOS’s gate, the PMOS’s source pin connects

to VCCL, and the PMOS

’s drain pin connects to CSN. The AP3306 drives PMOS on by pulling down the GDH pin voltage, and turns off PMOS by

pulling up on the GDH pin to VCCL.

U1

GND

VCCL

GDL

VCCH

AP3306

HV

FB

DEM

CS

GDH

8

3

1

9

5

4

6

PMOS

NMOS

CSN

GDH: 0  Turn ON POMS

GDH: VCC  Turn OFF

`

S

G

D

Figure 4. PMOS Driver Circuitry

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