Dual-phase boost/SEPIC controller for high-power density designs
The LTC3862IUH-1#PBF from Analog Devices is a current-mode PWM controller designed for boost and SEPIC topologies. It drives two external N-channel MOSFETs in a dual-phase configuration, effectively splitting the output current between two interleaved power stages. This reduces input and output ripple by cancellation and spreads the thermal dissipation across two inductor/MOSFET sets, which is useful when board space or component height limits a single large inductor. Switching frequency is programmable from 75kHz to 500kHz via a single resistor, and the controller can be synchronized to an external clock through the Clock Sync pin. The 96% maximum duty cycle supports high step-up ratios — useful when generating a 48V rail from a 12V input, for example — without the controller skipping pulses at high conversion ratios.
Control features and output configuration
Control features include Enable, Frequency Control, Phase Control, and Soft Start. The Phase Control pin sets the phase shift between the two output channels. The output configuration is Positive, with a Transistor Driver output type — meaning the controller drives external N-channel MOSFETs rather than integrating the switches. This gives the designer flexibility to select MOSFETs matched to the specific input voltage, output power, and switching frequency of the application. Synchronous rectification is not supported (Synchronous Rectifier: No), so the design uses Schottky diodes for the output rectifier stage. This is typical for boost and SEPIC controllers in this power class, where the efficiency gain from synchronous rectification is often offset by the added complexity and cost.
Package and mounting considerations
The shipping medium is Tube, so incoming inspection should account for tube-to-tube variations in lead coplanarity.
Lifecycle and sourcing reality
The LTC3862IUH-1#PBF carries an Active product status with ROHS3 compliance.