XP Power has designed the MTH100 hold-up module for maintaining short-term power to critical avionic and vetronic systems in the event of power drop-outs.   

Designed for use in systems with an input current up to 10A, the charger output voltage can be programmed allowing it to work with both military and industrial DC/DC converters.

Accommodating an input range of +10 to +40Vdc, the module automatically detects the input drop-out and initiates extended hold-up utilizing capacitors charged to a high voltage.

Charging the capacitors to a higher voltage than the nominal system voltage of +28 VDC, typically +36Vdc or +45Vdc, significantly reduces the amount of capacitance required.

Consider a power supply system that needs to operate through a power dropout of 200ms while supporting a 30W load without interruption using a DC/DC converter with a minimum input of 10V.

Without a hold-up module, if the power dropout occurs at 16V(in), the system would need over 90,000µF of capacitance, said the supplier.