2.7V super capacitor charger with additional 2-channel boost converter

The device is designed to charge 4 on-board 1.5F 2.7V super capacitors from a variety of DC sources like solar panels. Super capacitors management ensure that they are not overcharged by this extracted power.

In addition to the charger, the board integrates a highly efficient, nano-power 2-channel boost converter for providing a secondary power rail to systems such as wireless sensor networks. Output voltage from this converter is set at 3.3V.

Ultra Low Power DC-DC Boost Charger

• 300 nA Ultra-Low IQ in Low Power mode
• Startup into Load at 0.7 V Input Voltage
• Operating Input Voltage from 0.7 V
• After start-up converter operates down to 200mV
• Minimum 350 mA Switch Peak Current Limit
• Integrated Load Switch
• Two Modes Controlled by MODE Pin – Active Mode: Dual Outputs at Set Values – Low Power Mode: Load Switch Off; Boost Keeps On
• Automatic Pass-Through
• Up to 88% Efficiency at 10 µA Load from 2 V to 3.3 V Conversion (Low Power Mode)
• Up to 93% Efficiency at 5 mA ~ 100 mA Load from 2 V to 3.3 V Conversion

Energy Storage

Energy is stored in four 1.5F 2.7V super capacitors

Mode selection

Vsub is turned ON with a high signal on the middle pin of the mode connector. It can be connected to the High pin for continuous operation. Without any connections Vsub is in OFF state.

Storage

Schematic

Dimensions of the board are 39mm x 25mm x 14mm.