Analog Devices Inc./Maxim Integrated MAX8655ETN+

Overview

MAX8655ETN+ from Maxim Integrated is a highly integrated, synchronous PWM buck regulator with internal high- and low-side MOSFETs, delivering up to 25A output current across an adjustable 0.7V–5.5V range from a 4.5V–25V input. It employs peak current-mode control with externally adjustable 200kHz–1MHz switching frequency and supports 180° out-of-phase synchronization for multiphase operation. Used in point-of-load power supplies for servers, telecom, and notebook computers.

For engineers reviewing the MAX8655ETN+ datasheet, MAX8655ETN+ pinout, MAX8655ETN+ application, or MAX8655ETN+ equivalent, key selection considerations include its integrated 25A power stage, monotonic startup into prebiased outputs, independent overvoltage protection (OVP) sensing, adjustable valley/peak current limiting, and dual-mode reference input (0.7V internal or external up to 1.5V).

Technical Context

The MAX8655ETN+ implements a forced-PWM, peak current-mode architecture with an integrated transconductance error amplifier and programmable slope compensation. Its PWM comparator compares the summed current-sense signal and slope-compensation ramp against the integrated feedback voltage to determine high-side MOSFET on-time.

It integrates two LDOs: a 5V AVL rail powering internal logic and a 6.5V VL rail driving gate drivers. Startup requires VAVL > 4.15V, EN high, and thermal limits not exceeded; monotonic soft-start prevents negative output voltage during prebias conditions.

Key Specifications

Availability

MAX8655ETN+ is available at Aetrix Electronics and suitable for point-of-load power supplies, telecom base station DC-DC modules, and notebook CPU/GPU VRMs requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MAX8655ETN+ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power management ICs for demanding industrial, computing, and communications applications.

The MAX8655ETN+ belongs to Maxim's high-current, integrated buck regulator product line, engineered specifically for compact, high-efficiency point-of-load conversion in space-constrained, thermally challenging environments like servers and networking equipment.

FAQ

What is the package type and pin count of the MAX8655ETN+?

The MAX8655ETN+ uses a 56-pin TQFN-EP package (8mm × 8mm) with exposed pads for PVIN, LX, and GND. This thermally enhanced layout supports high-current operation by minimizing junction-to-board thermal resistance (θ_JC = 3.5°C/W), critical for sustaining 25A output in compact PCB footprints.

How does the MAX8655ETN+ achieve monotonic startup into a prebiased output?

The MAX8655ETN+ holds both internal MOSFETs off until the SS voltage exceeds the FB voltage, preventing reverse current flow and negative output excursions. This behavior is enabled by internal circuitry that compares SS and FB during soft-start, ensuring safe power-up when downstream loads are already powered - a key requirement for DDR memory and hot-swap systems.

Can the MAX8655ETN+ be synchronized to an external clock, and what phase relationship is supported?

Yes, the MAX8655ETN+ accepts an external clock (160kHz–1.2MHz) on the FSYNC pin and provides a 180° out-of-phase SYNCO output. When cascading two MAX8655ETN+ devices, connecting SYNCO of the master to FSYNC of the slave achieves interleaved operation, reducing input/output ripple current and easing filter design.

What are the options for current sensing and limiting on the MAX8655ETN+?

The MAX8655ETN+ supports dual-path current sensing: peak limit via CS+/CS− (using inductor DCR or external sense resistor) and valley limit via ILIM2. Peak limit offers higher accuracy; valley limit enables foldback during short-circuit events. MODE pin selects latch-off (MODE = AVL) or auto-recovery (MODE = GND) behavior.

Does the MAX8655ETN+ support external voltage references, and how is it configured?

Yes, the MAX8655ETN+ accepts an external reference up to 1.5V on the REFIN pin. When REFIN is tied to AVL, the internal 0.7V reference is used. When an external reference is applied, FB regulates to that voltage - enabling precise tracking in DDR applications or compatibility with higher-accuracy system references.