Choosing a Module

The PS-2 DC to DC converter can be supplied in a variety of standard voltages and custom voltages. The modules feature screw terminal inputs and outputs.

The useful output voltage range is from 1.2 Volts to the input voltage (Vin) minus 4 Volts. The PS-2 module requires at about 4Vdc of overhead to operate at the desired output.

Therefore: Vout <= Vin-4Vdc.

The useful output current depends on the current and voltage rating of the input voltage source. If you are using a battery supply or some other high power source, output current available will be the maximum of 1 Ampere. The PS-2 switcher module will operate at 90% efficiency or better at higher loads. If your are using a wall transformer or other power source with limited output, then use the following steps to determine maximum output current for your PS-2 module.

Step 1:

Calculate the output VA of the wall transformer (rated voltage output times rated current output). Some wall transformers may indicate a VA figure, but that is often the input VA from the power mains, this figure is not useful for our purposes.

VAin (to PS-2) equals the power source output voltage times the power source maximum output current.

VAin = Vo * Io

Step 2:

Multiply VAin by 0.90 to get the available output VA (we'll call VAout).

VAout = 0.90 * VAin

Step3:

Therefore: Iout-max = (VAout/Vout) or 1.0 Ampere, whichever is less.

For example, using a 24Vdc 100mA wall transformer as the power source and a PS-2 with 5.0Vdc output:

VAin = 24 * 0.10 = 2.4

VAout = 0.90 * 2.4 = 2.16

Iout-max = 2.16 / 5.0 = 0.432 or 432 mA

Not bad for a somewhat useless wall transformer!