Analog Devices Inc./Maxim Integrated MAX8878EZK28+T

Overview

MAX8878EZK28+T from Maxim Integrated is a low-noise, low-dropout linear regulator with 2.8V preset output, 150mA maximum output current, 165mV dropout at full load, 30µVRMS output noise, and 100µA operating supply current. It features auto-discharge during shutdown and reverse battery protection, designed for space-constrained portable electronics requiring stable, clean power from single-cell Li-ion or alkaline batteries.

For engineers reviewing the MAX8878EZK28+T datasheet, MAX8878EZK28+T pinout, MAX8878EZK28+T application, or MAX8878EZK28+T equivalent, key selection criteria include its thin SOT23-5 package, 2.8V ±1.4% accuracy, 10nA shutdown current, thermal/short-circuit protection, and BP-capacitor–enabled noise filtering - all critical for battery-life–sensitive handheld instrumentation and communication devices.

Technical Context

The MAX8878EZK28+T uses an internal P-channel MOSFET pass transistor (1.1Ω typical R_DS(ON)) to achieve low dropout and near-constant 100µA quiescent current across load and dropout conditions. Its error amplifier compares a 1.25V bandgap reference against feedback from an internal resistor divider tied to the OUT pin.

It integrates active auto-discharge via an internal 300Ω discharge path from OUT to GND when SHDN is asserted - a feature absent in the MAX8877 variant. The BP pin connects to a 200kΩ internal resistor and external 0.01µF capacitor to form an 80Hz low-pass filter, reducing output voltage noise to 30µVRMS (10Hz–100kHz).

Key Specifications

Pinout & Package

MAX8878EZK28+T is housed in a thin 5-pin SOT23 package (JEDEC MO-178AA), optimized for PCB area and thermal performance in high-density portable layouts. The GND pin serves as both electrical return and primary thermal path - requires connection to a large copper pour or ground plane.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise LDO applications.

Compared with MAX8878EZK28+T, MAX8877EZK28+T omits auto-discharge but matches all electrical specs and footprint - ideal for cost-sensitive designs without shutdown discharge requirements. MCP1702T-2802E/MB trades higher dropout and no BP filtering for lower IQ, making it suitable only for non-noise-critical digital rails.

Availability

MAX8878EZK28+T is available at Aetrix Electronics and suitable for cellular handsets, PCMCIA cards, hand-held instruments, and electronic planners requiring stable component supply, consistent parametric performance, and long-term lifecycle support.

Supply support for MAX8878EZK28+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 MAX8877/MAX8878 product line was engineered specifically for battery-powered portable electronics demanding ultra-low noise, minimal dropout, and guaranteed shutdown behavior - targeting design-in in handsets, modems, and handheld test equipment.

FAQ

What is the output voltage tolerance of the MAX8878EZK28+T over temperature and load?

The MAX8878EZK28+T guarantees ±1.4% output voltage accuracy across -40°C to +85°C ambient temperature and 0.1mA to 120mA load current. At 25°C and 0.1mA load, tolerance tightens to ±1.4% (not ±1%). This specification ensures reliable operation of 2.8V logic interfaces and analog sensors without external trimming.

Does the MAX8878EZK28+T require an external BP capacitor, and what happens if it's omitted?

Yes - the MAX8878EZK28+T requires a 0.01µF ceramic capacitor between BP and GND to achieve its specified 30µVRMS output noise. Omitting it increases noise to ~100µVRMS due to unfiltered reference noise, degrading performance in ADC reference or RF bias applications. Larger BP caps (>0.1µF) increase startup time without meaningful noise reduction.

How does the auto-discharge function work in the MAX8878EZK28+T during shutdown?

When SHDN is pulled low, the MAX8878EZK28+T activates an internal 300Ω switch between OUT and GND, discharging the output capacitor to near-zero volts within microseconds. This prevents residual voltage from powering downstream circuitry or causing undefined logic states - a key differentiator from the MAX8877EZK28+T, which lacks this feature.

Can the MAX8878EZK28+T operate with input voltages below 2.5V?

No - the MAX8878EZK28+T has a minimum input voltage rating of 2.5V per Absolute Maximum Ratings and Electrical Characteristics tables. Operation below 2.5V may cause regulation failure or undefined behavior. For sub-2.5V inputs, consider alternative regulators such as the MAX1726 or TPS7A05 series.

What thermal derating applies to the MAX8878EZK28+T in its thin SOT23-5 package?

In the thin SOT23-5 package, the MAX8878EZK28+T has a thermal resistance θ_JB of 110°C/W. Continuous power dissipation must be derated above +70°C ambient at 9.1mW/°C - limiting max dissipation to 727mW at +70°C. To sustain 150mA at high VIN–VOUT differentials, ensure GND pin is soldered to ≥25mm² copper area.