High-efficiency 4-output switching element controller using power management chip MAX1777-1977

High-efficiency 4-output switching element controller using power management chip MAX1777-1977

Some laptop motherboard power supply circuits use a multi-channel regulated power supply circuit composed of the MAX 177W1977 chip, as
shown in the figure. Its basic structure is the same as the power management circuit composed of the MAX 1999 chip. It also converts one DC voltage provided by the battery
into multiple DC voltage outputs. There are two sets of PWM signal generation circuits inside, and the battery or adapter
supplies power to the switching field effect transistor and control chip respectively.
    After the MAX 1777/1977 chip gets the voltage, it starts to generate a PWM signal. The LX5 and DL5 pins output a set of switching
pulses with opposite phases to provide PWM drive pulses for the field effect transistors Nl and N2. After being filtered by L5 and C5, a regulated DC voltage of 5 V is output.
The other set is passed through the field effect transistors N3 and N2. N4 enables the two field effect transistors to output, and then after filtering by L3 and C3, a regulated DC
voltage of 3.3 V is output.