Microchip Technology MCP1811AT-012/LB

Overview

MCP1811AT-012/LB from Microchip Technology is an ultra-low quiescent current (250 nA typical) 150 mA low-dropout linear regulator with fixed 1.2 V output, designed for energy-constrained systems requiring stable voltage under light-to-moderate load and deep sleep operation. It operates from 1.8 V to 5.5 V input, supports ceramic output capacitors as small as 1.0 µF, and includes output discharge during shutdown - confirming its identity as an MCP1811A-series LDO in 4-lead 1×1 mm UDFN package.

For engineers reviewing the MCP1811AT-012/LB datasheet, MCP1811AT-012/LB pinout, MCP1811AT-012/LB application, or MCP1811AT-012/LB equivalent, key selection criteria include ultra-low IQ (250 nA), 1.2 V fixed output, 150 mA capability, output discharge functionality, and UDFN-4 thermal performance (θJA = 91.05°C/W).

Technical Context

The MCP1811AT-012/LB implements a PMOS pass transistor architecture enabling ultra-low dropout (400 mV typical at 150 mA) and near-zero load-dependent quiescent current variation. Its internal error amplifier and reference maintain ±4% output accuracy over -40°C to +85°C junction temperature while supporting fast transient response via integrated output discharge switch (RDCH = 100 Ω typical).

It features active overcurrent protection with foldback limiting (50 mA at RLOAD = 1 Ω), shutdown logic with 70% VIN high threshold and 20% VIN low threshold, and stability with minimal 1.0 µF X7R ceramic output capacitance - eliminating need for electrolytic or tantalum alternatives.

Key Specifications

Pinout & Package

Package: 4-Lead 1×1 mm UDFN with exposed thermal pad (EP). Optimized for high-density PCB layouts and thermal dissipation on 4-layer FR4 boards (θJA = 91.05°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1811AT-012/OT and XC6210B122MR-G, the MCP1811AT-012/LB uniquely combines UDFN-4 thermal efficiency, guaranteed output discharge, and industry-leading 10 nA shutdown current - making it optimal for space-constrained, thermally demanding, and multi-rail battery systems.

Availability

MCP1811AT-012/LB is available at Aetrix Electronics and suitable for energy harvesting nodes, wearable medical sensors, and smart card interfaces requiring stable component supply with long-term lifecycle assurance.

Supply support for MCP1811AT-012/LB 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 microcontrollers, analog components, and Flash-IP solutions, serving automotive, industrial, consumer, and communications markets with vertically integrated silicon and software.

The MCP1811A/B series was designed specifically for ultra-low-power, long-life battery applications - emphasizing nanoscale quiescent current, minimal external components, and robust operation across wide temperature and input voltage ranges.

FAQ

What is the maximum continuous output current of the MCP1811AT-012/LB?

The MCP1811AT-012/LB delivers up to 150 mA continuously under specified thermal conditions (TA ≤ +85°C, θJA = 91.05°C/W on JEDEC 4-layer board). At higher ambient temperatures or with reduced copper area, derating applies - e.g., ~120 mA at TA = +70°C with no thermal vias. The device includes foldback current limiting to protect against sustained overload.

Does the MCP1811AT-012/LB require an external output capacitor, and what type is recommended?

Yes, the MCP1811AT-012/LB requires a minimum 1.0 µF X7R ceramic output capacitor placed adjacent to the VOUT and GND pins. This value ensures stability across all operating conditions and load currents. Tantalum or aluminum electrolytic capacitors are not required or recommended - the regulator is optimized exclusively for low-ESR ceramic types.

How does the output discharge feature work on the MCP1811AT-012/LB?

When SHDN is pulled low, the MCP1811AT-012/LB activates an internal discharge transistor (RDCH = 100 Ω typical) between VOUT and GND. This actively discharges the output capacitor to near-zero volts within microseconds, preventing residual voltage from back-powering downstream circuitry or interfering with system reset sequencing.

What is the input voltage range supported by the MCP1811AT-012/LB, and how does dropout behave at full load?

The MCP1811AT-012/LB operates from 1.8 V to 5.5 V input. At 150 mA load and TJ = +25°C, its typical dropout voltage is 400 mV - meaning it maintains regulation as long as VIN ≥ 1.6 V. Dropout increases slightly at temperature extremes (up to 600 mV max), so design margin should ensure VIN ≥ 1.8 V under worst-case conditions.

Is the MCP1811AT-012/LB pin-compatible with other variants in the MCP1811/12 family?

No - the MCP1811AT-012/LB uses a 4-lead UDFN package with pinout VIN-SHDN-VOUT-GND. It is not pin-compatible with 3-lead (SOT-23/SC70) or 5-lead variants. Substituting packages requires PCB redesign. Electrical compatibility exists within the MCP1811A family (e.g., same VR, IQ, and discharge function), but mechanical fit is package-specific.