Analog Devices Inc./Maxim Integrated MAX8891EXK18+T

Overview

MAX8891EXK18+T from Maxim Integrated is a fixed-output, low-dropout linear regulator delivering 1.8V at up to 150mA with 120mV dropout at 120mA load, 40µA ground current, and 65dB PSRR at 10kHz-designed for space-constrained battery-powered systems such as Bluetooth radios and digital cameras.

For engineers reviewing the MAX8891EXK18+T datasheet, MAX8891EXK18+T pinout, MAX8891EXK18+T application, or MAX8891EXK18+T equivalent, key selection criteria include guaranteed 150mA output, SC70 package footprint, 1µF ceramic capacitor stability, shutdown current <1µA, and thermal/overcurrent protection.

Technical Context

The MAX8891EXK18+T uses an internal p-channel MOSFET pass transistor (R_DS(ON) ≈ 1Ω) to achieve low dropout and eliminate base-drive current loss. Its bandgap reference (1.225V) feeds an error amplifier that controls gate drive to maintain regulation across input voltages from 2V to 6V.

Shutdown logic disables the reference, error amplifier, and gate driver when SHDN is pulled low, reducing supply current to <0.05µA at +85°C. Thermal protection activates at +160°C with 10°C hysteresis, cycling output during sustained overload without damage.

Key Specifications

Pinout & Package

Supplied in a 5-pin SC70 package (2.0mm × 1.25mm × 0.9mm), the MAX8891EXK18+T uses a compact footprint optimized for high-density portable PCBs. The GND pin serves dual roles: electrical reference and primary thermal path to the PCB ground plane.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS78218DRVR and MCP1700-1802E/TO, the MAX8891EXK18+T offers superior dropout performance (120mV vs. ≥178mV) and higher PSRR (65dB vs. ≤55dB), making it optimal for tight-input-margin, noise-sensitive applications where SC70 size is mandatory.

Availability

MAX8891EXK18+T is available at Aetrix Electronics and suitable for Bluetooth portable radios, digital cameras, personal stereos, and portable medical sensors requiring stable component supply, RoHS-compliant packaging, and long-term industrial availability.

Supply support for MAX8891EXK18+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) designs precision analog, mixed-signal, and power-management ICs for industrial, automotive, communications, and consumer applications.

The MAX8891/MAX8892 product line delivers high-PSRR, low-dropout regulation in ultra-small packages for battery-powered portable electronics where efficiency, size, and noise immunity are critical.

FAQ

What is the maximum input voltage rating for the MAX8891EXK18+T?

The MAX8891EXK18+T has an absolute maximum input voltage of +7V referenced to GND, but its operational input range is specified from 2V to 6V. Exceeding 6V may cause excessive power dissipation or violate safe operating area limits, especially at high ambient temperatures. For reliable long-term operation, keep VIN ≤6V and ensure thermal design accommodates P = I_OUT(V_IN − 1.8V).

Does the MAX8891EXK18+T require an external feedback resistor network?

No, the MAX8891EXK18+T does not require external feedback resistors. It is a factory-preset 1.8V regulator with internal trimming; pin 4 is labeled N.C. (not connected) and must remain unconnected. Only the adjustable MAX8892 variant uses the FB pin and external resistors-this distinction is confirmed in the Pin Description table and Typical Operating Circuits section of the datasheet.

Can the MAX8891EXK18+T be used with X7R ceramic capacitors smaller than 1µF?

No-the MAX8891EXK18+T is guaranteed stable only with ≥1µF ceramic output capacitance (X7R or X5R dielectric). Using smaller values risks oscillation or degraded transient response, as confirmed by the "Region of Stable C_OUT ESR vs. Load Current" graph and the Capacitor Selection section. Input capacitance also requires ≥1µF for robust line rejection and startup behavior.

What is the thermal shutdown behavior of the MAX8891EXK18+T during continuous overload?

When the MAX8891EXK18+T junction temperature exceeds +160°C, thermal shutdown activates and turns off the pass transistor. After junction temperature drops by 10°C (to +150°C), the device automatically resumes regulation. This results in pulsed output during sustained overload-confirmed in the Thermal-Overload Protection section-and protects the IC without requiring external intervention or latch-off circuitry.

How does the MAX8891EXK18+T compare to the MAX8892 in terms of pin compatibility and PCB layout?

The MAX8891EXK18+T and MAX8892 share identical 5-pin SC70 packages and pinouts, with only functional differences: pin 4 is N.C. on MAX8891EXK18+T but FB on MAX8892. PCB layouts designed for either part are mechanically interchangeable, but MAX8891EXK18+T boards must leave pin 4 floating-no trace or pad connection-while MAX8892 designs route it to an external resistor divider.