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Power
Converter The power converter is one of many subsystems created for the NSRV project. It is a general design that can be used in other projects. The power converter is an all surface mount circuit that boosts or steps up +1.2 VDC to +14VDC up to +14VDC at 1 AMP in a 1" x 1.25" package. The switching regulator operates near 90% efficiency and doesn't require a heat sink even at full output current at +85°C. The circuit shown is configured for +9.0 VDC output.  Power Converter. Theory of Operation DC battery power in the range 1.2 to 9.0 volts is provided on JP1. The LM2621 switching regulator operates in a boost mode. The LM2621, 6.8uH inductor, and diode boost the input voltage to the desired output. Tantalum capacitors C1 and C3 provide filtering. R1 and R2 form a divider network to reference the output voltage to 1.21V. C4 provides high frequency coupling to reduce output ripple. R5 sets the switching frequency. R4 and C6 provide filtered power to the LM2621. The LP2981 is a low drop out regulator that limits the boost and power voltage to +5VDC for the LM2621. Below +5VDC, the LM2621 internally boosts the input voltage to control the switch FET gate. R3 and the LED provide visual indication the power converter is operational. Schematic / PCB Layout For best quality, print the schematic on a single 8½ x 11" sheet of paper in landscape mode using your favorite graphics application.
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