Multi-topology regulator with a 4 A switch
The LT1271CQ#PBF is a current-mode switching regulator from Analog Devices that supports step-up, step-down, and step-up/step-down topologies — specifically Buck, Boost, Buck-Boost, and Flyback configurations. It delivers up to 4 A on the internal switch, rated at a 60 kHz switching frequency. The output is adjustable from a 1.244 V reference up to 60 V (switch voltage limit), and can be configured for positive or negative output polarity. Input voltage range spans 3.5 V to 30 V, suiting it for industrial and telecom rails that vary widely.
Package and thermal footprint — D2PAK-5
Housed in a TO-263-6 / D2PAK (5 leads plus tab) surface-mount package, also referred to as DDPAK-5. The exposed tab on the bottom provides a low thermal resistance path to the PCB copper plane — critical for dissipating heat from the 4 A switch in continuous operation. Supplied in Tube packaging. The part is ROHS3 compliant per the manufacturer's lifecycle record.
Lifecycle and sourcing posture
The 60 kHz switching frequency and non-synchronous architecture (no synchronous rectifier) are fixed parameters to verify against the target load profile.