Primary-Side CC/CV Flyback Controller with 700V Current Source

The MP023 from Monolithic Power Systems is an offline, primary-side controller that provides accurate, constant voltage and constant current regulation without the need of an optocoupler or secondary feedback circuit. It uses an integrated 700V current source to achieve quick start-up. It is designed to operate over a line voltage range of 85- to 265-Vac with a maximum switching frequency of 75kHz. The MP023 incudes programmable cable compensation.

The MP023's variable off-time control allows its flyback converter to operate in discontinuous conduction mode (DCM). The MP023’s current limit and maximum secondary duty cycle are programmable, making the output current easily set. The FB voltage sensing point is also programmable and is able to set different switching frequencies.

The internal high-voltage start-up current source and power-saving technologies limit the no-load power consumption to less than 30mW. Full protection features include VCC under-voltage lockout (UVLO), overload protection (OLP), over-temperature protection (OTP), open loop protection (OCkP), and over-voltage protection (OVP).

The MP023's variable switching frequency method provides a natural spectrum for shaping a smooth EMI signature, which is suitable for offline, low-power battery chargers and adapters. Applications are expected to include: power supplies for white goods, adapters for handheld electronics and standby and auxiliary power supplies.

The MP023 requires a minimal number of readily available, standard, external components and is available in a SOIC8-7A package.