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                  Home > PWM Controller
                  UC3801 Datasheet
                    

                  LOW COST POWER-SAVING MODE PWM CONTROLLER FOR FLYBACK CONVERTERS

                   

                   

                  DESCRIPTION

                   

                  The UTC UC3801 provides a CCM/valley switching mixed

                  mode operation for better efficiency performance. The operation

                  mode stays at CCM at heavy load, and switch to valley switching at

                  light load.

                  The UTC UC3801 is a high performance current mode PWM

                  controller ideally suited for low standby power. Low VCC startup

                  current make the power reliable on startup design and a large

                  value resistor could be used in the startup circuit to minimize the

                  standby power. At no load condition, the IC operates in

                  power-saving mode for lower standby power, decreasing frequency

                  for Higher conversion efficiency at light load condition.

                  The UTC UC3801 contains protection with automatic recovery

                  including OLP (over load protection), OCP (cycle-by-cycle current

                  limiting), and UVLO (VCC over voltage clamp and under voltage

                  lockout). It also provides the protections including OTP (over

                  temperature protection), BNO(AC Brown Out protection) , LNO(AC

                  Over voltage protection), OVP (VCC or DC output over voltage

                  protection) with automatic recovery. To protect the power

                  MOSFET, Gate-drive output is fixed up to 16V max.

                  The internal slope compensation improves system stability at

                  high PWM duty cycle output. Leading-edge blanking on current

                  sense input removes the signal glitch, which offering minima

                  external component count in the design. Excellent EMI

                  performance is achieved with UTC proprietary frequency hopping

                  technique (ZL201020615247.1) together with soft driver control.

                  Audio noise is eliminated due to switch frequency more than 20kHz

                  during operation.

                  UTC UC3801 is packaged by using tiny SOT-26 package. It has

                  such applications as: battery charger, power adaptor, set-top box

                  power supplies, ink jet printers, open-frame SMPS.

                   

                  FEATURES

                   

                  * Proprietary frequency hopping for Improved EMI performance

                  * Cycle-by-cycle current limiting

                  * CCM/Valley Switching Operation

                  * Fixed switch frequency 60~70kHz

                  * Dynamic peak current limiting for constant output power

                  * Built-in synchronized slope compensation

                  * Gate output voltage clamped at 16V

                  * Adjustable DC output OVP/UVP/OTP

                  * OLP/VCC OVP/OTP/BNO/LNO (automatic recovery)

                  * Internal Soft Start

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