System and Method to Increase a Hold Up Time of a Power Supply Unit

A multiple power supply system comprising:

• a first power supply unit to provide a main output voltage while in a normal mode of operation;
• and
• a second power supply unit to provide the main output voltage while in the normal mode of operation, the second power supply unit including:
• a bulk capacitor;
• and
• standby power circuitry, the standby power circuitry including a digital signal processor, the digital signal processor to control a charging of the bulk capacitor while the second power supply unit is in a reverse charging mode.

A method comprising:

• detecting a loss of a first input voltage source to a first power supply unit of a multiple power supply system, the multiple power supply system including the first power supply unit and a second power supply unit;
• operating the first power supply unit in a reverse charging mode of operation in response to the loss of the first input voltage source;
• charging a bulk capacitor of the first power supply unit while in the reverse charging mode of operation;
• determining whether a voltage level of the bulk capacitor is equal to a threshold voltage level;
• providing a lower charging cycle in the reverse charging mode of operation in response to the second bulk capacitor being charged to a predetermined voltage level;
• detecting a loss of a second input voltage source to the second power supply unit;
• operating in a hold up mode of operation in response to the loss of the first input voltage source;
• and
• providing an output voltage from the bulk capacitor while in the hold up mode of operation.