Analog Devices Inc./Maxim Integrated MAX8840ELT21+T

Overview

MAX8840ELT21+T from Maxim Integrated is a preset 2.1V, ultra-low-noise, high-PSRR, low-dropout linear regulator delivering up to 150mA output current with 120mV dropout at 120mA load, 11µV_RMS output noise (100Hz–100kHz), and 78dB PSRR at 1kHz - designed for powering noise-sensitive RF and analog circuitry in portable battery-powered devices.

For engineers reviewing the MAX8840ELT21+T datasheet, MAX8840ELT21+T pinout, MAX8840ELT21+T application, or MAX8840ELT21+T equivalent, key selection criteria include guaranteed 150mA output capability, stable operation with only 1µF ceramic output capacitance, sub-1µA shutdown current, and µDFN-6 (1.5mm × 1.0mm) package compatibility with space-constrained PCB layouts.

Technical Context

The MAX8840ELT21+T employs a p-channel MOSFET series pass transistor (typical R_DS(ON) = 1Ω) enabling low ground current (40µA typical) and eliminating base-drive losses common in PNP-based LDOs. Its bandgap reference (1.225V) feeds an error amplifier that controls the pass transistor gate to maintain precise 2.1V output regulation across load (100µA–120mA) and temperature (−40°C to +85°C).

Noise reduction is achieved via a dedicated BP pin connected to a 10nF capacitor between BP and OUT, which shunts high-frequency noise from the internal reference and error amplifier. During shutdown, the voltage reference, error amplifier, and gate drive are disabled, reducing supply current to <1µA while placing the output in high-impedance state.

Key Specifications

Pinout & Package

MAX8840ELT21+T is housed in a lead-free, RoHS-compliant 6-pin µDFN package measuring 1.5mm × 1.0mm × 0.8mm, with exposed thermal pad (GND-connected) for enhanced thermal performance in compact layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS79521DCQ and MCP1702T-2102E/MB, the MAX8840ELT21+T delivers superior noise performance (11µV_RMS vs. ≥30µV_RMS) and smaller footprint (1.5mm × 1.0mm vs. ≥3.0mm × 3.0mm), making it optimal for RF and audio subsystems where signal integrity and space constraints dominate design priorities.

Availability

MAX8840ELT21+T is available at Aetrix Electronics and suitable for cellular transceivers, portable audio codecs, digital camera image sensors, and low-power MCU core supplies requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for MAX8840ELT21+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 applications.

The MAX8840 family was engineered specifically for ultra-low-noise, high-PSRR power delivery in space-constrained, battery-operated RF and portable electronics - prioritizing noise floor, dropout efficiency, and µDFN integration over raw current capacity.

FAQ

What is the output voltage tolerance of the MAX8840ELT21+T over temperature and load?

The MAX8840ELT21+T guarantees ±3% output voltage accuracy across the full operating temperature range (−40°C to +85°C) and load current (100µA to 80mA). At +25°C and 1mA load, typical accuracy is ±1%. This tight tolerance ensures reliable operation of downstream 2.1V-tolerant analog and RF circuitry without external trimming.

Does the MAX8840ELT21+T require an external bypass capacitor, and if so, what value is recommended?

Yes - the MAX8840ELT21+T requires a 10nF ceramic capacitor connected between the BP pin and the OUT pin to achieve its specified 11µV_RMS output noise. Values below 1nF or above 100nF degrade noise performance. The capacitor must be placed as close as possible to the BP and OUT pins to minimize parasitic inductance.

Can the MAX8840ELT21+T operate with input voltages below 2.1V?

No - the MAX8840ELT21+T requires a minimum input voltage of 2V, but stable regulation at 2.1V output demands VIN ≥ VOUT + dropout. With 120mV dropout at 120mA, the lowest functional input is 2.22V. Below this, the device enters dropout and output voltage drops linearly with VIN.

How does the MAX8840ELT21+T behave during shutdown, and what is the output state?

When SHDN is pulled low (≤0.4V), the MAX8840ELT21+T disables its voltage reference, error amplifier, and pass transistor gate drive, reducing supply current to <1µA. The OUT pin transitions to a high-impedance state - neither sourcing nor sinking current - preventing backfeeding into the load or affecting other rails.

Is the MAX8840ELT21+T compatible with standard 1µF ceramic output capacitors, and are there dielectric restrictions?

Yes - the MAX8840ELT21+T is stable with any 1µF X5R or X7R ceramic capacitor across the full −40°C to +85°C range. Z5U and Y5V dielectrics are not recommended due to large capacitance and ESR shifts at temperature extremes; for those, ≥2.2µF is required to ensure stability below −10°C.