onsemi NCP1945 Power Factor Controllers for Adapters

onsemi NCP1945 Power Factor Controllers for Adapters are integrated controller ICs that combine power factor correction (PFC) and quasi-resonant (QR) flyback control to enable efficient, high-performance off-line USB-PD and USB Type-C^® power converters. The NCP1945's PFC stage is optimized for near-unity power factor and high efficiency across load conditions, operating in critical conduction mode (CrM) at higher power levels. As load decreases, it transitions to a discontinuous conduction mode (DCM) using an innovative Valley Synchronized Frequency Fold-back (VSFF) technique, which increases dead-time and reduces switching frequency to minimize losses.

These devices also feature a QR current-mode flyback stage with valley-lockout circuitry for stable switching, transitioning to frequency foldback, and eventually skip mode as load decreases to improve light-load efficiency. The ICs include adaptive control features, such as reflected-voltage sensing, minimum-peak-current modulation, and constant-current limiting regardless of output voltage. To ensure robustness, the onsemi NCP1945 integrates comprehensive protection mechanisms including brownout detection, non-dissipative overpower protection, overvoltage and overtemperature protection, and line removal detection for safe discharge of X2 capacitors.

Features

PFC
- Follower boost capability
- Fast line/load transient compensation (dynamic response enhancer)
- Adjustable enable threshold
Integrated high-voltage startup circuit with brownout detection
Integrated X2 capacitor discharge capability
Dual range V_CC, with 150V VccH pin for connection to high voltage auxiliary winding
Primary side-based constant output current limiting
Latching or auto-recovery timer-based overload protection
Fault pin for severe fault conditions, NTC compatible for OTP
PONOFF pin to set the PFC entry and exit point
PEM enables the use of low bulk capacitance

QR
- Abnormal overcurrent fault protection for winding short circuit detection
- Valley switching operation with valley-lockout for noise-free operation
- Frequency foldback with 25kHz minimum frequency
- Rapid frequency foldback for fast reduction of switching frequency
- Frequency jittering for reduced EMI signature
- Adjustable overpower protection
- Fixed maximum frequency clamp in Power Excursion Mode (PEM)
Lead-free and RoHS-compliant

Applications

Industrial power supplies
USB power delivery (PD)

Adapters
LED drivers

Specifications

Supply voltage ranges
- 16.0V to 18.0V startup threshold range
- 8.5V to 9.5V minimum operating range
- 7.5V minimum operating hysteresis
30mA maximum supply input current
1V/µs maximum supply input voltage slew rate
10mA maximum fault input current
500mA to 800mA maximum driver current range
10mA maximum input current (all other pins)
450mW maximum power dissipation
Typical thermal shutdown
- +140°C rated
- +40°C hysteresis
- 30µs delay

-40°C to +125°C operating junction temperature range
225°C/W maximum junction-to-ambient thermal resistance
Maximum ESD capability
- 2000V Human Body Model (HBM) per JEDEC Standard JESD22-A114E
- 1000V Charge Device Model (CDM) per JEDEC Standard JESD22-C101E
- ±100mA latch-up protection per JEDEC Standard JESD78
SOIC-20 NB package