ON Semiconductor NCP4354 Secondary
Side SMPS OFF Mode Controller
ON Semiconductor's NCP4354 Secondary Side SMPS OFF Mode Controller is a secondary side SMPS controller designed for use in applications which require extremely low no load power consumption. The device is capable of detecting 'no load' conditions and entering the power supply into a low consumption OFF mode. During OFF mode, the primary side controller is turned off and energy is provided by the output capacitors thus eliminating the power consumption required to maintain regulation. During OFF mode, the output voltage relaxes and is allowed to decrease to an adjustable level. Once more energy is required, it automatically restarts the primary side controller. During normal power supply operation, the devices provide integrated voltage feedback regulation, replacing the need for a shunt regulator. This device includes an LED driver pin implemented with an open drain MOSFET driven by a 1kHz square wave with a 12.5% duty cycle for indication purpose.