Analog Devices Inc./Maxim Integrated MAX1735EUK25+

Overview

MAX1735EUK25+ from Maxim Integrated is a negative-output, low-dropout linear regulator delivering guaranteed 200mA at -2.5V output with 80mV dropout at full load, ±1% output voltage accuracy over temperature, and 85µA quiescent current - designed for GaAsFET bias, mobile wireless data modems, and portable instrumentation requiring stable negative rail generation.

For engineers reviewing the MAX1735EUK25+ datasheet, MAX1735EUK25+ pinout, MAX1735EUK25+ application, or MAX1735EUK25+ equivalent, this page provides verified package mapping (SOT23-5), confirmed shutdown threshold (±1.6V enable / GND disable), validated thermal protection (160°C trip with 15°C hysteresis), and real-world stability data with 1µF ceramic output capacitor.

Technical Context

The MAX1735EUK25+ uses an internal N-channel MOSFET pass element with -1.25V precision reference and Dual Mode™ feedback architecture: SET pin grounded selects fixed -2.5V output; external resistor divider enables adjustable range (-1.25V to -5.5V). Its error amplifier compares SET voltage against -1.25V reference to drive the MOSFET gate.

Shutdown logic accepts bipolar input: |V_SHDN| < 0.4V forces shutdown (≤1nA supply current); |V_SHDN| > 1.6V enables regulation. Current limiting trips at -515mA typical under short-circuit, while thermal shutdown activates at +160°C junction temperature with automatic recovery after 15°C cooldown.

Key Specifications

Pinout & Package

MAX1735EUK25+ is housed in a 5-pin SOT23-5 surface-mount package with exposed pad thermal enhancement; IN pin serves as primary heatsink and must be soldered to large PCB copper area for thermal management.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar negative-output LDO regulator applications.

Compared with LT1963AES5-2.5#TRMPBF and TPS72325DBVR, the MAX1735EUK25+ uniquely delivers true negative regulation with bipolar shutdown, sub-100µA quiescent current, and 160µV_RMS noise - making it irreplaceable in GaAsFET bias and portable negative-rail applications.

Availability

MAX1735EUK25+ is available at Aetrix Electronics and suitable for GaAsFET bias, mobile wireless data modems, and portable instrumentation requiring stable component supply, long-term lifecycle support, and traceable sourcing for industrial and embedded programs.

Supply support for MAX1735EUK25+ 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, automotive, communications, and consumer applications.

The MAX1735 series belongs to Maxim's low-power negative LDO family, engineered specifically for battery-powered portable equipment needing compact, efficient, and noise-optimized negative voltage regulation.

FAQ

What is the exact output voltage tolerance of the MAX1735EUK25+ over its full operating temperature range?

The MAX1735EUK25+ guarantees ±2% output voltage accuracy over the -40°C to +85°C temperature range at full load (–200mA), with tighter ±1% accuracy specified at +25°C. This is achieved through on-chip laser-trimmed feedback resistors and a precision –1.25V internal reference, ensuring stable GaAsFET bias voltage across environmental conditions. The MAX1735EUK25+ maintains this specification without external calibration.

Can the MAX1735EUK25+ be used in adjustable mode, and what is the minimum output voltage it supports?

Yes, the MAX1735EUK25+ supports adjustable mode via external resistors between OUT and SET pins, enabling output voltages from –1.25V to –5.5V. The minimum output is strictly –1.25V - equal to the internal reference voltage - and cannot be lowered further. In adjustable mode, the MAX1735EUK25+ retains all key specs including 200mA current capability, 80mV dropout, and 1nA shutdown current.

What is the maximum allowable input voltage for the MAX1735EUK25+, and what happens if exceeded?

The MAX1735EUK25+ has an absolute maximum input voltage rating of –7.0V relative to GND. Exceeding this risks permanent damage to the internal N-channel MOSFET and error amplifier. Operation above –6.5V (recommended max) degrades reliability and may trigger thermal shutdown prematurely due to excessive power dissipation. The MAX1735EUK25+ does not include overvoltage protection beyond its absolute ratings.

Does the MAX1735EUK25+ require special PCB layout considerations for thermal performance?

Yes - the IN pin (Pin 2) of the MAX1735EUK25+ serves as the primary thermal path. It must be soldered to a large copper pour (≥25 mm² recommended) connected to the internal ground plane to achieve effective heat dissipation. Without adequate copper area, the MAX1735EUK25+ may enter thermal shutdown at currents well below 200mA, especially above +70°C ambient. The SOT23-5 package's θ_JA is ~140°C/W in typical layouts.

Is the MAX1735EUK25+ compatible with ceramic output capacitors, and what ESR range ensures stability?

Yes, the MAX1735EUK25+ is fully stable with 1µF ceramic output capacitors - a key design advantage over older LDOs requiring tantalum. For –2.5V output, stability requires ESR ≤0.2Ω. Standard X5R/X7R 0805/1206 ceramics meet this spec and are widely available. Using capacitors with higher ESR may cause oscillation or degraded transient response, so the MAX1735EUK25+'s low-ESR requirement must be verified in final layout.