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The RT7220D is a Synchronous Rectifier (SR) controller for Flyback converters operating in Continuous Conduction Mode (CCM), Discontinuous Conduction Mode (DCM) and Quasi-Resonant (QR) mode. The RT7220D will sense the drain voltage of MOSFET to determine SR gate on/off so as to minimize turn-off dead-time and enhance efficiency.
The RT7220D supports the wide output voltage range from 3V to 21V, and a HV LDO is especially built-in for the MOSFET gate driver at low output voltage. When it works with the primary-side controller RT7757, the Zero-Voltage-Switching (ZVS) control can be enabled to optimize the efficiency at high line.
Furthermore, the RT7220D provides a green mode operation in light load condition, which reduces operation current to be under 250μA.

Applications

  • USB PD Power Converters
  • Fast-Charger Power Adapeters
  • General Purpose High-Efficiency and/or Compact-Size Flyback Power Converters
Key Spec.
RT7220DHQ RT7220DLP
Status Active Active
Turn-On Threshold (V) 3.25 3.25
Turn-Off Threshold (V) 2.75 2.75
Operating Current (mA) 1.35 1.35
Green Mode Current (uA) 200 200
Maximum Input Voltage (V) 21 21
Maximum Operation Frequency (kHz) 120 120
Maximum VD Rating (DC Continue) (V) 160 160
Maximum VD Rating (Pulse width 500ns) (V) 160 160
HV LDO Current Capability (mA) 65 65
VG Total Turn-Off Delay Less than (ns) 50 50
Features Built-in HV LDO;Green Mode;High-Side SR Controller Of Flyback in CCM;DCM and Quasi-Resonant Mode+;VG Fast Turn-Off;VG Initial Output Low Clamping;VG Minimum Off-Time;VG Minimum On-Time;VG Output High Clamping Built-in HV LDO;Green Mode;Low-Side SR Controller Of Flyback in CCM;DCM and Quasi-Resonant Mode;VG Fast Turn-Off;VG Initial Output Low Clamping;VG Minimum Off-Time;VG Minimum On-Time;VG Output High Clamping
Package Type WQFN3x3-16 WQFN3x3-16
Features
  • Suitable for Flyback Converter in CCM, DCM and Quasi-Resonant (QR) Mode
  • Suitable for 3V to 21V VOUT Range
  • ZVS Function to Optimize Efficiency (Work with the Primary-Side Controller RT7757)
  • <1.65mA Operating Current in ZVS Mode
  • <250μA Operating Current in Green Mode
  • Built-in HV LDO to Supply SR Driver when VOUT Lower than 5V
  • Automatic Dead-Time Tracking Control to Optimize Efficiency
  • Protection
    ► SR Gate Driver with 6V Clamp
    ► SR Gate Initial Pull-Low before Start-Up
    ► SR Minimum Off-Time
    ► Fast Turn-Off (<50ns) Gate Driver
Datasheet
TitleLast UpdateDownload
Synchronous Rectifier Controller with Zero Voltage Switching for Wide Output Voltage Operating Range2022/11/04
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