Product Description
PL3378 is a high efficiency Primary Side Regulator and
highly integrated PWM Power Switch for AC/DC power
supply applications. It simplifies conventional CC/CV
charger/adaptor designs by eliminating the opto-coupler
and secondary control circuitry. Constant output voltage
and current regulation is realized as shown in the Fig.1
below. Multi-mode operations are utilized to achieve low standby
power, high efficiency and audio & noise free. PL3378
operates in PFM mode at large load condition, with the
load becomes medium or light, the chip operates in Green
mode to achieve high efficiency. PL3378 also offers rich protection features including
Cycle-by-Cycle peak current limiting, UVLO, OTP, load
OVP, and VDD over voltage.

Key Features
• Built-in Integrated Power BJT• Accurate Constant Current
Regulation at Universal ACinput • Eliminates Opto-coupler andall
Secondary CC/CV Control Circuitry• Built-in Line Compensationfor
Tighter CC/CV Regulation
• Built-in Compensation for
Transformer Inductance
Tolerances
• Adjustable Output Cable
Compensation
• Adaptive Multi-mode PFMControl for Improving Efficiency• Low Start-up Current • Built-in Leading Edge Blanking(LEB) • Cycle-by-Cycle Current Limiting• VDD Under Voltage Lockout andVDD over voltage protection• Built-in Short Circuit ProtectionandOutput Overvoltage Protection• Over temperature protection

Applications
AC/DC power supply applications• Cell Phone Charger • Small Power Adaptor/Charger • LED Driver • Standby Supply for Consumer
Electronics