Analog Devices Inc./Maxim Integrated MAX8840ELT29+T

Overview

MAX8840ELT29+T from Maxim Integrated is a 2.85V fixed-output, ultra-low-noise LDO linear regulator delivering up to 150mA with 120mV dropout at 120mA load, 11µV_RMS output noise (100Hz–100kHz), and 78dB PSRR at 1kHz. It uses a p-channel MOSFET pass element, achieves 40µA ground current, and operates from 2V to 6V input in space-constrained portable power rails.

For engineers reviewing the MAX8840ELT29+T datasheet, MAX8840ELT29+T pinout, MAX8840ELT29+T application, or MAX8840ELT29+T equivalent, key selection criteria include its 2.85V preset output, µDFN-6 package footprint, BP-capacitor–enabled noise suppression, shutdown current <1µA, and guaranteed stability with 1µF ceramic output capacitance.

Technical Context

The MAX8840ELT29+T implements a bandgap-referenced error amplifier driving a 1Ω (typ) p-channel MOSFET pass transistor, enabling low dropout and minimal quiescent current across load and temperature. Its dedicated BP pin accepts a 10nF capacitor to shunt high-frequency noise from the internal reference path, directly enabling the 11µV_RMS noise performance.

Shutdown control disables the reference, error amplifier, and gate driver, reducing supply current to <1µA while placing OUT in high-impedance state. Thermal shutdown activates at +160°C with 10°C hysteresis, and current limiting clamps output to 150–300mA depending on conditions.

Key Specifications

Pinout & Package

MAX8840ELT29+T is housed in a 1.5mm × 1.0mm × 0.8mm lead-free µDFN-6 package with exposed thermal pad (pin 5 is N.C., not internally connected). The package requires standard reflow profile and PCB land pattern per Maxim drawing 21-0147.

Key Features

Applications

Equivalent & Alternatives

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

Compared with the Torex XC6219B282MR-G and ADP125ARHZ-2.85-R7, the MAX8840ELT29+T uniquely delivers 2.85V precision with 11µV_RMS noise via BP-pin architecture in the smallest footprint (1.5mm × 1.0mm), making it optimal for RF and high-fidelity analog power where noise and size are primary constraints.

Availability

MAX8840ELT29+T is available at Aetrix Electronics and suitable for cellular handsets, Bluetooth accessories, and portable medical devices requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX8840ELT29+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 MAX8840 series belongs to Maxim's ultra-low-noise LDO product line, engineered specifically for noise-sensitive analog and RF subsystems in battery-powered portable electronics where PSRR, dropout, and quiescent current are critical.

FAQ

What is the exact output voltage tolerance of the MAX8840ELT29+T?

The MAX8840ELT29+T has a guaranteed output voltage tolerance of ±3% over temperature (-40°C to +85°C) and load (100µA to 80mA), per the Electrical Characteristics table. At +25°C and 1mA load, typical accuracy is ±1%. This 2.85V output is factory-trimmed using laser calibration on the internal feedback divider, ensuring tight regulation without external components.

Does the MAX8840ELT29+T require an external bypass capacitor on the BP pin?

Yes, the MAX8840ELT29+T requires a 10nF capacitor between BP and OUT to achieve its specified 11µV_RMS output noise. Without this capacitor, noise increases to 230µV_RMS. The BP pin is internally shorted to OUT during shutdown, so the capacitor remains safe. Use X7R or C0G dielectric with low leakage (<10nA) for optimal performance.

Can the MAX8840ELT29+T operate with input voltages below 2.85V?

No - the MAX8840ELT29+T requires a minimum input voltage of 2V, but regulation is only maintained while VIN ≥ VOUT + dropout. With 120mV dropout at 120mA, the lowest functional input is 2.97V. Below that, output collapses linearly. For sub-2.85V inputs, the device enters dropout and cannot sustain 2.85V output.

What is the thermal performance of the MAX8840ELT29+T in its µDFN package?

The MAX8840ELT29+T has a θ_JA of 477°C/W in the standard µDFN-6 package. With 150mA load and 3.5V input (0.65V drop), power dissipation is 97.5mW, resulting in ~46°C junction rise above ambient. To stay within the +150°C max junction rating, keep ambient ≤ +104°C. Use GND pad thermal vias to reduce θ_JA by up to 40%.

Is the MAX8840ELT29+T pin-compatible with other MAX8840 variants like MAX8840ELT33+T?

Yes - all MAX8840 variants (e.g., MAX8840ELT29+T, MAX8840ELT33+T) share identical µDFN-6 pinout, package dimensions, and electrical interface. Only the factory-set output voltage differs. No PCB redesign is needed when substituting between MAX8840 voltage options; only firmware or system-level voltage margin validation is required.