I am deriving load regulation for 7.5V 2Amp. linear power supply, but I am confused regarding the equation of percentage load regulation.
which of 3 is correct?
1....Load Reg = {(Vn - Vf) / Vf} x 100%
where Load Reg = load regulation;
Vn = no-load output voltage;
Vf = full-load output voltage
OR
2....Load Reg. = V full load -V Minimum Load
--------------------------
V nominal load
Where:
FullLoad is the load that draws the greatest current (is the lowest specified load resistance - never short circuit)
MinimumLoad is the load that draws the least current (is the highest specified load resistance - possibly open circuit for some types of linear supplies, usually limited by pass transistor minimum bias levels)
NominalLoad is the typical specified operating load
Thanks, I have designed 7.5V 2 Amp. power supply using LM338, 230 to 12V 3Amp. Transformer, Bridge Rectifier having 1.1V Forward drop per bridge and filter capacitor around 20000MF.
I am having load regulation of around 1.06 percentage, but I read that linear power supply can give regulation of 0.01 %, how to achieve this?
It might not need a regulated supply, a 6V transformer with a bridge rectifier and 22,000µF capacitor might do.
The datasheet for the LM338 specifies a worst case of 0.6%, however it has a thermal stability of 1% meaning the output voltage can drift by 1% over the temperature range. Given the heating of the die, the regulation and the resistance of the wires, it woudln't surprise me if this could amount to 1.06%.