This solution stores and delivers "last gasp" energy for systems, such as SSDs, that require functionality for a short time after power loss in order to shut down in a controlled fashion. By storing holdup energy at higher than bus voltage the amount of capacitance can be reduced by up to 80%, significantly reducing solution size and cost while improving reliability.
Typically a complex electronics circuit is needed to boost the input voltage, mux it with the buck input during power failure, and bucking it down to 3.3V or 5V for the load.
This reference design uses TI’s TPS25942 on the input side to control inrush, protect against over voltage, under voltage, short circuits, and prevent stored energy from flowing back to a shorted input bus. The boost converter charges the capacitor bank to 12V if input supply is 5V, or 18V if input supply is 12V. When the TPS25942 detects and declares a fault the FLTb signal is used to drive a P-MOSFET that connects the storage capacitors to the buck input.
- "Last Gasp" Holdup Energy for controlled turn off.
- Reduces solution size and cost while increasing reliability
- Provides multiple levels of protection to load and bus.
- External controller not required.
- Prevents holdup energy from flowing back onto a shorted bus.