The LTC3600 from Linear Technology is a high efficiency, monolithic synchronous buck regulator whose output is programmed with just one external resistor. The accurate internally generated 50 µA current source on the I_SET pin allows the use of a single external resistor to program an output voltage that ranges from 0 V to 0.5 V below V_IN. The V_OUT voltage feeds directly back to the error amplifier in unity gain fashion and equals the I_SET voltage. The operating supply voltage range is 4 V to 15 V, making it suitable for dual lithium-ion battery and 5 V or 12 V input point-of-load power supply applications.

The operating frequency is synchronizable to an external clock or programmable from 200 kHz to 4 MHz with an external resistor. High switching frequency allows the use of small surface mount inductors. The unique constant on-time architecture is ideal for operating at high frequency in high step-down ratio applications that also demand fast load transient response.