Nexperia adaptive Synchronous Rectifier (SR) controller ICs NEX8180x
Secondary side controller improve overall system reliability in advanced charging solutions
The NEX81801DA and NEX81802DA (NEX81801/2DA) are high performance synchronous rectification controllers used in switching mode power supplies. It supports operation in Discontinuous Conduction Mode (DCM), Continuous Conduction Mode (CCM) and quasi-resonant flyback converters. The NEX81801/2DA regulates the forward drop voltage of an external synchronous rectifier (SR) MOSFET in two stages. This allows the SR FET to turn off quickly when the VDS becomes positive. The externally adjustable turn-on blanking time can effectively prevent the synchronous rectifier from being falsely turned off due to leakage inductance and parasitic parameter oscillation. The adaptive turn-on detection circuit can prevent the SR from being mistakenly turned on when the VDS DCM oscillation crosses zero during some load conditions. The adaptive turn-on detection circuit also enhances SR conduction efficiency during light load conditions, thereby improving the average efficiency of the power supply across the entire load range. The synchronous switch can be configured at high-side or low-side output without auxiliary windings or other power sources, because the NEX81801/2DA has a self-supply capability. The NEX81801/2DA uses TSOT23-6 packaging with low thermal resistance. This can effectively reduce the junction temperature of the chip, making it suitable for high-density power supply design.
Key features
- Supports DCM, CCM, QR operation
- Supports up to 800 kHz switching frequency
- Standard and logic level MOSFET driving capability
- Wide output range down to 0 V with 2-channel VCC supply
- No need for auxiliary winding for high-side or low-side rectification
- Smart proportional gate driver for fast SR turn-off at CCM
- Adjustable turn-on blanking time for increased noise immunity
- Proprietary adaptive turn-on detection prevents SR FET from falsely turning on during DCM operation
- 10 ns typical turn-off propagation delay
- ESD protection | HBM: ANSI/ESDA/JEDEC JS-001 class 2 exceeds 2000 V. CDM: ANSI/ESDA/JEDEC JS-002 class C2a exceeds 500 V
Applications
- USB PD/QC chargers
- AC/DC adapters for portable devices
- Flyback SMPS with high-efficiency requirements
- Battery chargers for e-bikes / e-tools
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