Analog Devices Inc./Maxim Integrated MAX1735EUK25+T

Overview

MAX1735EUK25+T from Maxim Integrated is a negative-output, low-dropout linear regulator delivering a guaranteed -2.5V output at up to 200mA with 80mV dropout at full load, ±1% output voltage accuracy over temperature, and 85µA quiescent current - designed for GaAsFET bias and portable wireless modem power rails.

For engineers reviewing the MAX1735EUK25+T datasheet, MAX1735EUK25+T pinout, MAX1735EUK25+T application, or MAX1735EUK25+T equivalent, this page provides verified package mapping (SOT23-5), confirmed Dual Mode™ operation (preset -2.5V or adjustable -1.25V to -5.5V), thermal shutdown at +160°C, 1nA shutdown current, and PSRR >60dB at 100Hz.

Technical Context

The MAX1735EUK25+T uses an internal N-channel MOSFET pass transistor with -1.25V precision reference and error amplifier feedback control, enabling stable regulation in both fixed (-2.5V) and adjustable modes via SET pin configuration. Its Dual Mode™ comparator selects between internal preset divider and external resistor network based on SET voltage level.

It features active shutdown logic compatible with ±1.6V enable thresholds, allowing direct TTL-level positive drive or negative-rail control without level shifting. Thermal protection cycles output at +160°C junction with 15°C hysteresis, and short-circuit current limit is specified at -515mA typical under VOUT = 0.

Key Specifications

Pinout & Package

Package: SOT23-5 - compact 5-pin surface-mount package with exposed pad thermal path; requires soldering IN pin to large PCB copper area for thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2937-2.5 and LT1963A-2.5, the MAX1735EUK25+T is uniquely qualified for negative-rail applications requiring sub-100mV dropout, 1nA shutdown, and SOT23-5 footprint - making it irreplaceable in GaAsFET bias and dual-polarity modem designs.

Availability

MAX1735EUK25+T is available at Aetrix Electronics and suitable for GaAsFET bias, mobile wireless data modems, notebook computer subsystems, and PCMCIA card power management requiring stable component supply across industrial temperature range (-40°C to +85°C).

Supply support for MAX1735EUK25+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) is a U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and consumer markets.

The MAX1735 series belongs to Maxim's precision negative LDO regulator product line, engineered specifically for battery-powered portable equipment requiring ultra-low IQ, tight output accuracy, and robust thermal protection in miniature packages.

FAQ

What is the exact output voltage of MAX1735EUK25+T?

The MAX1735EUK25+T is factory-trimmed to deliver a precise -2.5V output voltage with ±1% accuracy at +25°C and ±2% over the full -40°C to +85°C operating range. This preset value is achieved by connecting the SET pin to GND; the device does not require external resistors for fixed-voltage operation.

Does MAX1735EUK25+T support adjustable output voltage?

Yes, the MAX1735EUK25+T supports adjustable output voltage from -1.25V to -5.5V using an external resistor divider between OUT and SET pins. Although its marking "ADOX" and ordering code indicate -2.5V preset, the underlying Dual Mode™ architecture allows reconfiguration - the SET pin must be disconnected from GND and biased via R1/R2 per the formula VOUT = -1.25V × (1 + R1/R2).

What is the minimum input voltage required for MAX1735EUK25+T to regulate at full load?

The MAX1735EUK25+T requires a minimum input voltage of -2.58V to maintain regulation at 200mA load, calculated from its 80mV dropout specification (|VIN| ≥ |VOUT| + 0.08V). At lighter loads, dropout decreases - e.g., at 10mA, dropout is ~10mV, allowing VIN as low as -2.51V while sustaining -2.5V output.

How does the SHDN pin interface with standard logic levels?

The SHDN pin of MAX1735EUK25+T accepts both positive and negative enable signals: driving SHDN ≥ +1.6V or ≤ -1.6V enables regulation, while 0V (GND) forces shutdown with <1nA supply current. This dual-threshold design allows direct connection to 3.3V/5V TTL outputs without level shifters, and also supports negative-rail control in bipolar systems.

Is MAX1735EUK25+T stable with ceramic output capacitors?

Yes, the MAX1735EUK25+T is fully stable with 1µF or greater X7R/X5R ceramic capacitors on the output, regardless of ESR - a key advantage over older LDOs requiring minimum ESR for phase margin. For -2.5V output, no special capacitor selection is needed; stability is guaranteed across 1µF–10µF range with typical 0.01Ω–0.1Ω ESR ceramics.