Demonstration circuit DC290 is a constant-frequency step-down converter using an LTC®1877 or an LTC1878 monolithic synchronous regulator. The LTC1878 has an input voltage range of 2.65V < VIN < 6V and the LTC1877 has an input voltage range of 2.65V < VIN < 10V. The LTC1878 is optimized for low voltage operation and is ideally suited for single Li-Ion cell or 3-NiCd/NiMH cell applications. The LTC1877, with its higher voltage capability, is ideally suited for two Li-Ion cells or 4- to 6-NiCd/NiMH cell applications.