Boost regulator for 5V rails from single-cell Li-Ion
The LTC3529EDCB#TRPBF is a step-up (boost) switching regulator from Analog Devices that delivers a fixed 5V output from an input range of 1.8V to 5.25V. The internal switch is rated for 1.5A, so the actual output current depends on the input-to-output voltage ratio and the inductor selection — at a 3.3V input, expect roughly 900 mA continuous output before the switch current limit is reached. The 1.5 MHz switching frequency keeps the inductor and output capacitor physically small, which matters when board area is tight. The synchronous rectifier (a MOSFET replacing the usual Schottky diode) improves efficiency by a few percent across the load range — the extra die area in the 8-DFN package pays back in lower thermal dissipation at 1A output.
Package and layout considerations
The pad is the main heat path — a four-layer board with thermal vias under the pad is the standard layout for full 1.5A switch current at high ambient. The 1.5 MHz switching frequency means the input capacitor should be placed within a few mm of the VIN and GND pins to keep the switching loop small. A 10 µF ceramic input cap with a 6.3V or higher rating is typical; the output capacitor can be 22 µF ceramic for the fixed 5V rail.