MP1584 Power IC and Buck circuit analysis

MP1584 step-down converter Buck converter produced by the US-sourced semiconductor http://www.monolithicpower.com/. Its core is buck conversion!

The following is an analysis of the buck circuit.

The buck Circuit also belongs to the switching power supply. By adding a switching signal PWM to the MOS tube Q to control the on and off of the switching tube, the inductor and capacitor charge and discharge, the diode used here is the Schottky diode, which is characterized by fast recovery. Compared to ordinary diodes, ordinary diodes will be burned due to high switching frequency resulting in large leakage of heat.

Popular science, in switching power supply, there are six types of single-tube DC-to-digital converters, i.e. Buck (Buck)DC-to-digital converters, step -up (boost)DC-to-AC converters, boost Buck (Buck Boost) DC /DC converters,Cuk /DC converters,Zeta/DC converters, and SEPIC /DC converters. Of these six single-tube DC-to converters,Buck and Boost DC-to-digital converters are basic , derived from the Buck-boost, Cuk, Zeta, and sepic DC converters.

Volt-Second principle: in a stable state of the inductor, switch on-time (current rise) of the number of volts seconds must be switched off (current drop segment) when the number of volts seconds is equal, although the two symbols opposite.

Formula:Δvon Ton =δvoff Toff

So we can exit the buck circuit:

(VIN-VO) *dt=vo* (1-d) Tvo=vin *DD is the duty ratio, which is expressed here is the inductance charge voltage (Vin-vo) and the product of the charge time equals the voltage of the inductive discharge (VoMultiplied by the discharge time. Therefore, the purpose of buck can be achieved by controlling the duty ratio. From another point of view, the inductance and capacitance constitute a low-pass filter, so that the output voltage as far as possible is the DC component, the inductor continues to flow, to ensure continuous current, capacitance to ensure the stability of the output voltage! The typical application circuit for MP1584 is used on flat-panel devices.
The input voltage range is 4.5-28v output maximum current of 3 a.
Typical voltages such as output 1.8v,3v,5v can be configured. In the D1,L1,C2 formed a typical buck melted down, you can see that the D1 circuit symbol is a Schottky diode.

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MP1584 Power IC and Buck circuit analysis