FEATURES
Standby power less than 75mW
Primary-side Sensing and Regulation
Without TL431 and Opto-coupler
High precision constant voltage and
current regulation at Universal AC input
Programmable CV and CC Regulation
Multi-mode PWM/PFM operation for
efficiency improving
Audio noise free operation
Programmable Cable Drop
Compensation
Built-in line voltage and primary winding
inductance compensation
No need for control loop compensation
Built-in CS Open Protection
VDD Over Voltage Protection and
Clamp Protection
Built-in Short Circuit Protection
Built-in Leading Edge Blanking (LEB)
Over temperature protection(OTP)
Cycle-by-Cycle Current Limiting
VDD Under Voltage Lockout with
Hysteresis (UVLO)
DIP-8L/SOP-7L green Packaging
APPLICATIONS
Switching AC/DC Small Power Adaptor
Cell Phone Charger
Digital Cameras Charger
Auxiliary Power for PC, TV etc
Linear Regulator/RCC Replacement
GENERAL DESCRIPTION
CR6245 CR6247 CR6248 CR6249 is a high performance offline PSR controller for low power AC/DC charger and
adapter applications, Less than 75mW standby power consumption with typical application. It
operates in primary-side sensing and regulation,so opto-coupler and TL431 could be eliminated.
In CC control, the current and output power setting can be adjusted externally by the sense resistor
R S at CS pin. In CV control, PFM operations are utilized to achieve high performance and high
efficiency. In addition, good load regulation is achieved by the built-in cable drop compensation.
CR6245 CR6247 CR6248 CR6249 offers comprehensive protection coverage with auto-recovery features including
Cycle-by-Cycle current limiting, VDD over voltage protection and clamp protection, CS open
protection, short circuit protection, built-in leading edge blanking, VDD under voltage lockout
(UVLO).
PINASSIGNMENT
OPERATION DESCRIPTION
CR6245 CR6247 CR6248 CR6249is a cost effective PSR power switch optimized for off-line low power AC/DC
applications including battery chargers. It operates in primary side sensing and regulation, thus
opto-coupler and TL431 are not required. Proprietary built-in CC/CV control can achieve high
precision CC/CV control to meet most charger application requirements.
CC/CV Operation
CR6245 CR6247 CR6248 CR6249 is designed to produce good CC/CV control. In charger applications, a discharged
battery charging starts in the CC portion of the curve until it is nearly full charged and smoothly
switches to operate in CV portion of the curve. The CC portion provides output current limiting.
In CV operation, the output voltage is regulated through the primary side control. In CC operation
mode, CR6245 CR6247 CR6248 CR6249 will regulate the output current constant regardless of the output voltage drop.
Principle of Operation
To support CR6245 CR6247 CR6248 CR6249 CC/CV control, system needs to be designed in DCM mode for flyback
system. In the DCM flyback converter, the output voltage can be sensed via the auxiliary winding.
During MOSFET turn-on time, the load current is supplied from the output filter capacitor. The
current in the primary winding ramps up. When MOSFET turns off, the energy stored in the
primary winding is transferred to the secondary side. The current in the secondary winding is
