# Expert Talk: What is a Power Converter (SMPS)?

## Open online SPICE simulator circuit link: learn_power_converter_220V_overview_startup.tsc

A power converter transfers electric energy from a given source (input) to an energy sink (load)

in a well regulated manner. Infineon products and solutions help designer to achieve this task in an

easy, efficient and safe way. An energy source can be the power grid (AC) or a battery (DC).

Energy sink (Load) can be resistive (heater, LED), capacitive (bulb), inductive (motor, valve)

or a combination of them (CPU, FPGA).

Converter Types

- AC-AC: Transformer

- AC-DC: Rectifier

- DC-DC: Topologies like buck, boost, buck-boost, flyback, etc.

- DC-AC: Inverter (Motor, Solar)

Converter Realization

- Linear regulators: use semiconductor components in linear mode: low efficiency, bigger size, but low EMI noise

- Switching regulators: use components in swiched mode: higher efficiency, smaller size, but high EMI noise

- Power path: converts energy from the input source to the output load

- Control path: controls the power path for well regulated transfer, highest efficiency and stable operation

Example: Swiched mode power supply (SMPS) for charging adapter

set your CCM converter spec in the Interpreter window on the left, click on Run to calculate the parts and simulate it

- Input: 170 VAC

- Output: 12 VDC

- Current: 1 A

Circuit on the left: Flyback converter with two stages

- AC-DC Converter: Rectifier stage

- DC-DC Converter: Flyback topology

Important Note (Disclaimer)

This is an idealized circuit for learning and experimental use. Test carefully when using calculated values for real hardware.

Expert talk: how to design a Power Converter?

+

{1. click here to set application parameters}

{2. click on "Run" to calculate components}

{3. click on "OK" and Simulate Transient }

{Input voltages [V]}

V_in_ac:= 170 {use 100... 300}

V_in_dc:= 0.9*V_in_ac {after rectification}

V_in_dc=[153]

{Output voltage [V]}

V_out:= 12 {set smaller than V_in_dc}

{Output current [A]}

I_out:= 1 {use 1 .. 4}

R_load:= V_out/I_out

R_load=[12]

{Transformer}

N1:= 10 {Primary winding}

N2:= 1 {Secondary winding}

Ratio:= -N2/N1 {voltage Ratio}

Ratio=[-100m]

{=== Control settings: change with care ! ===}

{Switching frequency [Hz]}

fs:= 50k {use 100k .. 300k}

{Duty cycle}

Duty:= 1/(1+(V_in_dc/V_out*N2/N1))

Duty=[439.5604m]

L_INIT:= (V_out*I_out)/V_in_dc { DC value}

C0_INIT:= V_in_dc {capacitor DC value}

C_INIT:= V_out

T:=1/fs

T_on:= Duty*T

T_off:=T-T_on

ControlT2:=T_on

ControlT4:=T_off

{Calculate components for CCM}

L_crcm:= ((1-Duty)^2*R_load)/(2*fs*(N2/N1)^2)

L_crcm=[3.7691m]

L:= 2*L_crcm

L=[7.5382m]

R_crcm:= (2*L*fs*(N2/N1)^2)/(1-Duty)^2

R_crcm=[24]

AC-DC Converter (Rectifier)

Flyback Topology (DC-DC)

Technical Assistance

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\a(Power Selection Guide,https://www.infineon.com/dgdl/Infineon-Power_and_Sensing_Selection_Guide_2018-SG-v00_00-EN.pdf?fileId=5546d4625607bd13015621522aa012cb)

\a(Automotive Power Guide

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