Low Power Backup with Supercapacitor

A power supply system with a supercapacitor has a wide input voltage range which supports from 3V to 40V with a 2.5A output. A supercapacitor can be used to replace the traditional battery (with defects such as electrolyte leakage) as a backup power supply.

In boost mode, the buck-boost regulator can discharge the capacitor energy as much as the present electronic components, which maximizes the use of capacitive energy and helps save cost. When the load is small, the discharge efficiency can be as high as 82% at 100mA. At high current (1A output), this design can still achieve over 50% discharge efficiency. The high-performance LDO, high-efficiency MOSFET and precise voltage supervisor provide the integrated power system solution.

System Benefits:

• ISL85403 can fully extract the power of the supercapacitor (can be as low as 0.3V).
• ISL88002 voltage supervisor to monitor the power status.
• ISL9001A is a high-performance LDO with low I_SUPPLY and high PSRR.
• RJK03M5DNS N-MOSFET support for high-efficiency drive and low heat design.