Microchip Technology MCP1811BT-025/TT

Overview

MCP1811BT-025/TT from Microchip Technology is an ultra-low quiescent current (250 nA typical) 150 mA low-dropout linear regulator with fixed 2.5 V output, designed for energy-constrained battery-powered systems. It operates from 1.8 V to 5.5 V input, features shutdown mode with 5 nA typical supply current, and remains stable with only 1.0 µF ceramic output capacitance - enabling use in hearing aids and smart wearables.

For engineers reviewing the MCP1811BT-025/TT datasheet, MCP1811BT-025/TT pinout, MCP1811BT-025/TT application, or MCP1811BT-025/TT equivalent, key selection criteria include ultra-low IQ operation, 2.5 V fixed output accuracy (±4%), thermal performance in SOT-23 package, and compatibility with micro-power MCUs in sleep-mode-sensitive designs.

Technical Context

The MCP1811BT-025/TT belongs to the MCP1811B variant family, meaning it provides 150 mA output current and **no output discharge** during shutdown (unlike MCP1811A). Its internal architecture uses a PMOS pass transistor to achieve low dropout voltage (400 mV typical at 150 mA) while maintaining ultra-low ground current (90–110 µA over load range).

It supports full operational junction temperature range (–40°C to +85°C), includes overcurrent protection and foldback current limiting (50 mA at 1 Ω load), and delivers high PSRR (–50 dB at 1 kHz) without input capacitor - critical for noise-sensitive analog sensor rails and RF subsystems powered from shared battery sources.

Key Specifications

Pinout & Package

Package: 3-Lead SOT-23 - surface-mount, JEDEC-standard footprint with thermal performance of θ_JA = 211.33°C/W on 4-layer FR4 board.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1811BT-025/TT, XC6206P252MR-G eliminates shutdown functionality but reduces footprint and cost, while RP111N251B-TR-F adds output discharge and 50 mA extra current headroom at the expense of larger 5-pin package and higher minimum VIN (2.0 V).

Availability

MCP1811BT-025/TT is available at Aetrix Electronics and suitable for energy harvesting, long-life battery-powered medical devices, and wearable electronics requiring stable component supply with guaranteed long-term sourcing.

Supply support for MCP1811BT-025/TT 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

Microchip Technology Inc. is a leading provider of microcontroller, mixed-signal, analog, and Flash-IP solutions, headquartered in Chandler, Arizona.

The MCP1811 series was designed specifically for ultra-low-power, battery-critical applications such as hearing aids, smart cards, and energy-harvesting nodes - prioritizing nanoscale IQ, ceramic-capacitor compatibility, and robust thermal behavior in miniature packages.

FAQ

What is the shutdown behavior of the MCP1811BT-025/TT?

The MCP1811BT-025/TT is part of the MCP1811B variant, which does not include output discharge functionality. When SHDN is pulled low, the regulator stops regulating and VOUT floats - no internal transistor pulls VOUT to GND. This preserves downstream capacitor charge and avoids unintended resets in systems requiring hold-up voltage.

Does the MCP1811BT-025/TT require an input capacitor?

No, the MCP1811BT-025/TT is specified to maintain stability and deliver –50 dB PSRR at 1 kHz without an input capacitor. However, a local 100 nF ceramic capacitor at VIN is recommended to suppress high-frequency noise from upstream sources - especially when sharing input rails with switching regulators or digital ICs.

Can the MCP1811BT-025/TT operate from a single alkaline cell?

Yes - the MCP1811BT-025/TT supports input voltages as low as 1.8 V, making it compatible with a single alkaline cell (nominal 1.5 V, fresh up to 1.65 V, end-of-life ~0.9 V). However, regulation ceases below ~2.9 V input due to its 400 mV dropout; thus, it's best paired with cells that retain >2.9 V for most of their discharge curve, such as lithium coin cells (CR2032) or two-series NiMH.

What is the thermal resistance of the MCP1811BT-025/TT in its SOT-23 package?

The MCP1811BT-025/TT in 3-Lead SOT-23 has a junction-to-ambient thermal resistance (θ_JA) of 211.33°C/W when mounted on a JEDEC-standard 4-layer FR4 board with 1 oz. copper. At 150 mA load and 5.5 V input, worst-case power dissipation is ~525 mW, resulting in ~111°C junction rise - well within the +125°C absolute maximum, provided ambient stays ≤–26°C. For higher ambient, derating or thermal vias are advised.

How does the MCP1811BT-025/TT compare to the MCP1700 series?

The MCP1811BT-025/TT offers identical 250 nA quiescent current and 2.5 V output as the MCP1700-2502E/MB, but differs critically in shutdown current (5 nA vs. 1 µA) and output discharge (absent vs. present in MCP1700A). It also supports lower minimum input voltage (1.8 V vs. 2.7 V), making MCP1811BT-025/TT preferable for sub-2.7 V energy harvesting or single-cell lithium applications where every nanoamp counts.