The PSU-11 is a small power supply module that generates a +12V/-12V power output from a single +12VDC input supply and as such is an ideal DC-DC adaptor for a 12V battery.

The external 12V is passed through:-

• a filter direct to the +12V output terminal, and
• to an onboard DC-DC converter that generates the -12V terminal.

The PSU11-A is capable of delivering -12V @ 1.5A while the PSU11-B is capable of delivering -12V @ 3A.

The PSU-11 requires an external well-regulated 12VDC supply. When determining the loading capacity of the external supply you should determine the maximum +12V and -12V rail loadings and add them together to get the external supply capacity. You should, ideally, add about 25% to the individual rail loadings to allow for peak demands and to ensure that you are working within the limits of the PSU-11.

For example, if your system requires +12VDC @ 1.2A and -12VDC @ 600mA then the following calculations should be used:-

1.2A * 25% = 1.5A
600mA * 25% = 750mA

'output capacity of external supply' = 1.5A + 0.75A = 2.25A

12VDC @ 2.4A is the recommended minimum rating for the external supply.

The PSU11-A is suitable for this application as the -12V loading is within the maximum 1A rating.

The quality of the external supply is important. The supply should have low ripple and minimal noise figures. These requirements, of course, do not apply to a battery pack.

There is no post regulation on the PSU-11 outputs.

The PSU-11 is intended for installation, usually, within the equipment to be powered but this may not always be practical, in which case the PSU-11 can installed in a low-profile housing