Analog Devices Inc./Maxim Integrated MAX1725EUK-T

Overview

MAX1725EUK-T from Maxim Integrated is an ultra-low quiescent current, adjustable-output low-dropout linear regulator designed for battery-powered systems requiring extended runtime and tight output accuracy. It delivers 2µA supply current across its full operating range, supports 1.5V to 5V output via external resistor divider, maintains ±1.5% output voltage accuracy, and operates from +2.5V to +12V input-ideal for smoke detectors and real-time clock backup power.

For engineers reviewing the MAX1725EUK-T datasheet, MAX1725EUK-T pinout, MAX1725EUK-T application, or MAX1725EUK-T equivalent, key selection considerations include its 2µA IQ in dropout, 1.245V feedback reference, reverse-battery protection, thermal shutdown with 15°C hysteresis, and compatibility with 1µF ceramic output capacitors for stable load transients.

Technical Context

The MAX1725EUK-T uses a p-channel MOSFET pass transistor controlled by a precision 1.245V error amplifier, eliminating base-drive current losses inherent in PNP-based regulators. Its feedback architecture accepts external resistive dividers on the FB pin to set output between 1.5V and 5V, with typical FB bias current of 0.1nA enabling high-impedance resistor networks.

Shutdown is activated by driving SHDN below 0.5V, reducing supply current to 0.7µA while disconnecting the output. Reverse-battery protection limits VIN-to-GND reverse leakage to <10µA when VIN < 0V, and foldback current limiting caps short-circuit current at ~40mA (typ) without damage.

Key Specifications

Pinout & Package

MAX1725EUK-T 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 standard 0.95mm pitch. The package supports reflow soldering per JEDEC J-STD-020 (260°C peak).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX1725EUK-T, TPS78225DRVR offers lower IQ but forfeits adjustability and reverse-battery protection, while MCP1702T-3302E/MB provides higher output current and lower cost but doubles quiescent current and omits critical safety features for battery-reversal-prone environments.

Availability

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

Supply support for MAX1725EUK-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 battery-powered applications.

The MAX1725/MAX1726 product line was engineered specifically for ultra-low-power, long-life battery systems - emphasizing sub-µA-level quiescent current, reverse-polarity resilience, and minimal external component count.

FAQ

What is the feedback reference voltage of the MAX1725EUK-T?

The MAX1725EUK-T features a precision 1.245V feedback reference voltage (VFB), specified with ±2mV tolerance at +25°C and ±3mV over -40°C to +85°C. This value is used in the resistor-divider equation VOUT = VFB × (1 + R1/R2) to set the output voltage between 1.5V and 5V. The MAX1725EUK-T's low 0.1nA FB bias current ensures minimal error from resistor network loading.

Can the MAX1725EUK-T operate from a single lithium-ion cell?

No, the MAX1725EUK-T cannot reliably operate from a single lithium-ion cell. Its minimum input voltage is +2.5V, while a discharged Li+ cell falls to ~2.7V and may dip below 2.5V under load. The device is optimized for two Li+ cells (nominal 7.4V, range 6.0V–8.4V) or 9V alkaline batteries. Using it with a single cell risks dropout and regulation loss below 2.5V, making the MAX1725EUK-T unsuitable for that configuration.

Does the MAX1725EUK-T require an input capacitor?

Yes, the MAX1725EUK-T requires a minimum 1µF ceramic input capacitor (CIN) placed close to the IN and GND pins. This capacitor improves input supply-noise rejection, dampens line transients, and stabilizes operation during fast load steps. While the regulator remains stable without CIN under ideal lab conditions, omitting it risks erratic behavior in real-world systems with PCB trace inductance and noisy sources - especially critical in battery-powered smoke detectors where reliability is paramount.

How does shutdown affect the output voltage of the MAX1725EUK-T?

When the MAX1725EUK-T is placed in shutdown (SHDN < 0.5V), the internal p-channel pass transistor turns off completely, disconnecting the OUT pin from the IN supply. As a result, the output voltage decays to 0V through the load and any external pull-down paths. During shutdown, supply current drops from 2µA to 0.7µA, and the FB pin remains high-impedance. The MAX1725EUK-T does not actively pull OUT low - external circuitry must manage residual charge if rapid discharge is required.

Is the MAX1725EUK-T pin-compatible with the MAX1726 series?

No, the MAX1725EUK-T is not pin-compatible with MAX1726 variants despite sharing the same 5-pin SOT23 package and pinout numbering. While both use pins 1(IN), 2(GND), 3(OUT), 4(FB/GND), and 5(SHDN), the MAX1726 replaces FB with GND - meaning connecting a MAX1725EUK-T into a MAX1726-designed board would short FB to GND, disabling regulation. The MAX1725EUK-T requires external resistors on FB; substituting it for a MAX1726 demands schematic and layout changes.