4-phase buck controller with PMBus telemetry
The MAX20751EKX+ from Maxim Integrated is a 4-phase, 4-output step-down (buck) PWM controller designed for high-current processor core and memory rails. It integrates a PMBus serial interface for voltage margining, output current telemetry, and fault reporting. The switching frequency is programmable from 300kHz to 800kHz, allowing the designer to trade off inductor size against efficiency.
Control features and output configuration
Control features include phase control for interleaving, a power-good output for sequencing, and a ramp signal for slope compensation. The output configuration is positive — the controller drives external N-channel MOSFETs in a standard buck topology. Synchronous rectification is not built in; the design uses external Schottky diodes or MOSFETs for the low-side rectifier.
Package and mounting
Housed in a 36-pin VFQFN with exposed pad (6x6 mm body), the MAX20751EKX+ is surface-mount only. The exposed pad must be soldered to a ground plane for thermal dissipation — the junction-to-board thermal path relies on it. The supplier device package is 36-QFN (6x6).
Lifecycle and sourcing
The MAX20751EKX+ is listed as Active with ROHS3 compliance. No end-of-life notice or last-time-buy window has been issued.