MiscEl: Power Supply

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This page is used to design simple power supplies with 78xx and LM317 style regulator IC's.

Input values

KindSelect style of regulator, either 78xx or LM317
Analyze/DesignDesign mode will ask for a minimum number of parameters and then calculate/estimate everything else. Analyze is used to play with/optimize a design
C1Filter capacitor
VoutRequired output voltager, the actuel output voltage can depend on circuit
R1/R2These resistor defines output voltage on LM317 style regulators
ILoadMax. load on regulator output
FMains frequence, if no values is specified 50Hz is assumed
VtuTransformer unloaded output voltage
VtlTransformer output voltage when loaded with It
ItTransformer rated output current
TempTemperature around IC, 40 C is assumed when no value is specified
HSHeatsink in K/W
ICRegulator IC, selected from an internal database
OscilioscopeWhen checked a page with calculated waveforms is shown

Output values

WarningsSome conditions may give a warning, this usual means that some of the components must be changed
VoutActual output voltage, may not match requested voltage exactly for LM317 style regulators
R1/R2Voltage definition resistors
C1Filter capacitor
C2Output capacitor, recommend value from datasheet is shown
DPossible rectifier to use, many other can be used
ICRegulator IC. If a manufactur is listed, then specification from that manufactur is used
IC Heatsink max.Regulator IC needs a heatsink, the calculated value is the max. K/W value that can be used, a lower value is recommended.
Trafo rms currentEstimated RMS current from transformator
Trafo impedanceEstimated output impedance of tranformator, calculated as (Vtu-Vtl)/It
Diode peek current (Each cycle)Estimated. min. peek current rating of diode
Diode peek current (At turn on)Estimated min. on-time peek current rating of diode
C1 voltageEstimated voltage on C1 at max. load
IC temperaturEstimated IC temperature at max. load
Power inputEstimated power used in circuit, not including trafo standby use
Power loss in trafoEstimated power loss in trafo excluding standby power
Power loss in bridgeEstimated power loss in bridge
Power loss in ICEstimated power loss in IC regulator
Power to loadPower delivered to load
EfficiencyEstimated efficiency of the power supply at max. load

The assumptions used are




It is possible to make external tables with regulator specifications, for more information email me.