Analog Devices Inc./Maxim Integrated MAX17551AUB+T

Overview

The MAX17551AUB+T from Maxim Integrated is a high-voltage, synchronous step-down DC-DC converter with integrated MOSFETs, operating from 4V to 60V input and delivering up to 50mA output current. It supports adjustable output voltages from 0.8V to 0.9 × VIN, achieves ±1.75% feedback voltage accuracy over –40°C to +125°C, and features peak-current-mode control with selectable PWM or PFM operation. It is used in industrial sensors and high-voltage LDO replacement applications where ultra-small footprint and low quiescent current are critical.

For engineers reviewing the MAX17551AUB+T datasheet, MAX17551AUB+T pinout, MAX17551AUB+T application, or MAX17551AUB+T equivalent, key selection criteria include its 10-pin µMAX® package (3mm × 3mm), 22µA no-load supply current in PFM mode, programmable 100kHz–2.2MHz switching frequency via RT/SYNC, internal soft-start, and built-in RESET output with 92–95% regulation monitoring thresholds.

Technical Context

The MAX17551AUB+T implements an internally compensated peak-current-mode control architecture with separate high-side pMOS and low-side nMOS drivers. Its error amplifier compares FB voltage against a 0.8V reference, while slope-compensated PWM comparator sets on-time based on sensed inductor current and error voltage.

It supports dual operating modes: forced-PWM (MODE = GND) for fixed-frequency operation across all loads, and PFM (MODE unconnected) for pulse-skipping and zero-negative-inductor-current operation at light loads-enabling >90% peak efficiency and 22µA no-load IQ. The device includes monotonic startup into prebiased outputs, hiccup-mode overload protection, and thermal shutdown at +160°C with 20°C hysteresis.

Key Specifications

Pinout & Package

MAX17551AUB+T is supplied in a 10-pin µMAX® package (outline 21-0061, RoHS-compliant). The exposed pad (EP) is electrically connected to GND and must be soldered to a thermal pad on the PCB for optimal thermal performance (θ_JA = 113.1°C/W on four-layer board).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down regulator applications.

Compared with MAX17552AUB+T and LM5164QDDARQ1, the MAX17551AUB+T delivers optimal balance of ultra-low quiescent current (22µA), minimal external components, and industrial-grade reliability in the smallest possible footprint-making it ideal for space- and power-constrained sensor nodes where 50mA output suffices.

Availability

MAX17551AUB+T is available at Aetrix Electronics and suitable for industrial sensors and process control, high-voltage LDO replacement, and battery-powered equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX17551AUB+T 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 industrial, medical, and communications applications.

The MAX17551AUB+T belongs to Maxim's high-voltage DC-DC converter family, engineered specifically for ultra-compact, high-efficiency power conversion in harsh industrial environments where wide input range, low IQ, and robust protection are mandatory.

FAQ

What is the maximum input voltage rating for the MAX17551AUB+T?

The MAX17551AUB+T has an absolute maximum input voltage rating of 70V on the IN pin, with continuous operation specified from 4V to 60V. This allows reliable use in industrial 24V, 36V, and 48V systems, including transient surges common in motor control and building automation environments. Operation beyond 60V is not guaranteed and may trigger overvoltage protection or degrade long-term reliability.

Does the MAX17551AUB+T support external clock synchronization?

Yes, the MAX17551AUB+T supports external clock synchronization via the RT/SYNC pin-but only when the MODE pin is grounded to force PWM operation. An external clock must be AC-coupled through a 47pF capacitor, have logic-high >3V and logic-low <0.5V, and maintain 10–70% duty cycle. The internal RT resistor must be selected to set f_SW ~10% below the external clock frequency for stable locking.

How does the RESET output function on the MAX17551AUB+T?

The RESET output on the MAX17551AUB+T is an open-drain signal that pulls low when the FB voltage falls below 92% of its regulated value and goes high-impedance 2ms after FB rises above 95%. It asserts low during hiccup-mode fault recovery. This enables system-level power-good monitoring without additional supervisory ICs-critical for microcontroller reset sequencing in industrial controllers powered by the MAX17551AUB+T.

Can the MAX17551AUB+T start up into a prebiased output?

Yes, the MAX17551AUB+T supports monotonic startup into a prebiased output. When enabled, both high-side and low-side MOSFETs remain off until the first PWM pulse is commanded-preventing reverse current flow from the output capacitor into the IC. This protects downstream circuitry and avoids voltage overshoot or latch-up in systems where the output rail is held up by other sources during power-up.

What is the thermal performance of the MAX17551AUB+T in its µMAX® package?

In the 10-pin µMAX® package (U10+5), the MAX17551AUB+T has a junction-to-ambient thermal resistance (θ_JA) of 113.1°C/W on a standard four-layer PCB. With a maximum junction temperature of +150°C and ambient up to +125°C, this allows ~707mW continuous power dissipation at TA = +70°C before derating begins. Proper thermal pad connection to GND is essential to achieve these ratings.