Analog Devices Inc./Maxim Integrated MAX1725EUK

Overview

MAX1725EUK from Maxim Integrated is an ultra-low quiescent current (2µA), adjustable-output low-dropout linear regulator designed for battery-powered systems requiring extended runtime and tight output accuracy (±1.5%). It delivers up to 20mA output current with a 1.5V–5.0V programmable output via external resistor divider, operates from +2.5V to +12V input, and uses only 1µF output capacitance for stable load-transient response - ideal for smoke detector power rails and real-time clock backup.

For engineers reviewing the MAX1725EUK datasheet, MAX1725EUK pinout, MAX1725EUK application, or MAX1725EUK equivalent, key selection criteria include its 2µA supply current in dropout, reverse-battery protection, thermal shutdown at +150°C, SOT23-5 package footprint, and FB-based feedback architecture enabling precise voltage setting across wide temperature range (-40°C to +85°C).

Technical Context

The MAX1725EUK employs a p-channel MOSFET pass transistor controlled by a +1.245V precision error amplifier, eliminating base-drive current loss inherent in PNP regulators and sustaining 2µA quiescent current across full load and dropout conditions. Its feedback loop accepts external resistive dividers on the FB pin to set output between 1.5V and 5.0V with ±1.5% accuracy over temperature.

Shutdown is activated by driving SHDN < 0.5V, reducing supply current to 0.7µA while disconnecting OUT; reverse-battery protection limits VIN-reverse current to <10µA when VIN < 0V. Thermal shutdown engages at +150°C with 15°C hysteresis, and foldback current limiting caps short-circuit current to ~40mA (typ).

Key Specifications

Pinout & Package

MAX1725EUK is housed in a RoHS-compliant 5-pin SOT23 package (package code U5+1, outline 21-0057), measuring 2.9mm × 1.6mm × 1.1mm, with exposed pad not connected internally. Pin 1 (IN) accepts input voltage; Pin 2 (GND) provides ground reference; Pin 3 (OUT) delivers regulated output; Pin 4 (FB) senses feedback voltage for output adjustment; Pin 5 (SHDN) controls active-low enable/disable.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-quiescent-current LDO regulator applications.

Compared with MAX1725EUK, the TPS78033 offers lower IQ and higher output current but sacrifices adjustability and reverse-battery protection; the ADP160 achieves nanoscale IQ but removes critical safety features needed in consumer-facing battery compartments.

Availability

MAX1725EUK is available at Aetrix Electronics and suitable for smoke detectors, remote transmitters, and real-time clock backup power systems requiring stable component supply, long-lifecycle support, and guaranteed RoHS compliance.

Supply support for MAX1725EUK 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) is a semiconductor company specializing in analog, mixed-signal, and power-management ICs for industrial, medical, and battery-powered applications.

The MAX1725/MAX1726 product line was engineered specifically for ultra-low-power, long-duration battery systems - prioritizing quiescent current, reverse-polarity resilience, and minimal external component count over raw output current capability.

FAQ

What is the maximum output current supported by the MAX1725EUK?

The MAX1725EUK guarantees 20mA output current across its full operating temperature range (-40°C to +85°C). While short-circuit foldback limits peak current to ~40mA (typ), continuous operation above 20mA is not specified and may compromise regulation accuracy or thermal margin. For higher current needs, consider the MAX1726 series or alternate LDO families rated for >100mA.

Does the MAX1725EUK require an external resistor network to function?

Yes - the MAX1725EUK is an adjustable-output regulator and requires two external resistors connected between OUT, FB, and GND to set the output voltage within 1.5V–5.0V range. The FB pin references an internal +1.245V bandgap, and the resistor ratio determines final output per VOUT = 1.245V × (1 + R1/R2). Omitting the divider leaves FB floating and causes undefined output behavior.

Can the MAX1725EUK be used with a 12V lead-acid battery?

Yes - the MAX1725EUK supports input voltages up to +12V and includes reverse-battery protection that blocks current if VIN drops below ground. However, sustained operation at 12V input with >10mA load will exceed its 571mW power dissipation limit at +70°C ambient unless heatsinking or derating is applied. For 12V automotive use, verify junction temperature under worst-case load and ambient conditions using θJA = 140°C/W.

What is the purpose of the SHDN pin on the MAX1725EUK?

The SHDN pin on the MAX1725EUK is an active-low enable input: pulling it below 0.5V disables the regulator, dropping supply current to 0.7µA and disconnecting OUT from the pass transistor. For normal operation, connect SHDN to IN. When reverse-battery protection is required, drive SHDN through a 100kΩ resistor to isolate shutdown logic from reversed input polarity.

How does the MAX1725EUK achieve 2µA quiescent current in dropout?

The MAX1725EUK achieves 2µA quiescent current in dropout by using a p-channel MOSFET pass transistor instead of a PNP bipolar device. Unlike PNP regulators that draw significant base current - especially in saturation - the PMOS gate requires no steady-state drive current. This architecture eliminates base-drive losses and maintains ultra-low IQ regardless of input-to-output differential voltage, enabling full regulation down to VIN = VOUT + VDO.