Microchip Technology MCP1812AT-040/LB

Overview

MCP1812AT-040/LB from Microchip Technology is a 300 mA ultra-low-quiescent-current LDO regulator with 4.0 V fixed output, 250 nA typical IQ, and output discharge functionality (MCP1812A variant). It operates from 2.4 V to 5.5 V input, supports ceramic output capacitors ≥2.2 µF, and targets battery-powered systems requiring long operational life under light-load or sleep conditions - such as wearable medical sensors and energy-harvesting nodes.

For engineers reviewing the MCP1812AT-040/LB datasheet, MCP1812AT-040/LB pinout, MCP1812AT-040/LB application, or MCP1812AT-040/LB equivalent, this page delivers verified technical context, package-specific pin mapping, real-world application constraints, and validated alternative options for low-power system design and BOM optimization.

Technical Context

The MCP1812AT-040/LB implements a PMOS pass transistor architecture enabling ultra-low dropout voltage (400 mV typical at 300 mA) and stable regulation across –40°C to +85°C junction temperature. Its internal discharge transistor (RDCH = 100 Ω typical) actively pulls VOUT to GND during shutdown (SHDN = GND), eliminating residual voltage hold-up in power-gated subsystems.

It features foldback current limiting (100 mA at RLOAD = 1 Ω), ±25 mV load regulation over 1–300 mA, and –50 dB PSRR at 1 kHz with no input capacitor - critical for noise-sensitive analog rails powered from shared switching supplies.

Key Specifications

Pinout & Package

Package: 4-Lead 1 × 1 mm UDFN with exposed thermal pad (EP). Compact footprint ideal for space-constrained wearables and implantables; thermal resistance θJA = 91.05°C/W on JEDEC 4-layer board enables full 300 mA output without forced airflow.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B402MR-G and RP114K401D-TR-F, the MCP1812AT-040/LB uniquely delivers 300 mA output with integrated discharge and lowest IQ in its class - making it the only option for space-constrained, battery-critical designs requiring guaranteed VOUT collapse on disable.

Availability

MCP1812AT-040/LB is available at Aetrix Electronics and suitable for wearable electronics, medical sensors, and energy-harvesting IoT nodes requiring stable component supply, long-lifecycle assurance, and traceable sourcing for regulated end markets.

Supply support for MCP1812AT-040/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 is a global provider of microcontrollers, analog components, and Flash-IP solutions, serving automotive, industrial, communications, and consumer markets with vertically integrated silicon and software.

The MCP1811/12 family was designed specifically for ultra-low-power, long-life battery applications - emphasizing nanoscale quiescent current, ceramic-capacitor compatibility, and integrated power-control features like output discharge.

FAQ

What is the maximum input voltage rating for the MCP1812AT-040/LB?

The MCP1812AT-040/LB has an absolute maximum input voltage rating of +6.0 V. Operation above 5.5 V violates the recommended operating conditions and risks permanent damage. For reliable 4.0 V output, VIN must remain ≥4.4 V (4.0 V + 400 mV dropout) and ≤5.5 V per datasheet specifications.

Does the MCP1812AT-040/LB require an input capacitor?

The MCP1812AT-040/LB does not require an input capacitor for stability, but a 1 µF ceramic capacitor placed close to the VIN pin significantly improves PSRR and transient response. The device maintains –50 dB PSRR at 1 kHz even with no input capacitor, enabling simplified layout in space-constrained designs.

How does the output discharge feature work in the MCP1812AT-040/LB?

In the MCP1812AT-040/LB, asserting SHDN = GND activates an internal 100 Ω NMOS discharge transistor between VOUT and GND. This rapidly discharges the output capacitor - clearing VOUT to <100 mV within microseconds - preventing back-powering of downstream circuitry and ensuring deterministic power-down sequencing.

Can the MCP1812AT-040/LB operate with a 2.0 V input supply?

No. The MCP1812AT-040/LB requires a minimum input voltage of 2.4 V when delivering 300 mA (per Table 1, DS20006088C-page 4). At 2.0 V input, the device cannot regulate 4.0 V output and will drop out of regulation - resulting in uncontrolled VOUT collapse. Minimum VIN scales with load: 2.0 V is only valid for ≤150 mA (MCP1811X), not MCP1812X.

What is the thermal performance of the MCP1812AT-040/LB in its 1×1 mm UDFN package?

The MCP1812AT-040/LB in the 4-lead 1×1 mm UDFN package has a junction-to-ambient thermal resistance (θJA) of 91.05°C/W on a JEDEC-standard 4-layer FR4 board with thermal vias. With 300 mA load and 5.5 V input, power dissipation is ~450 mW - resulting in ~41°C junction rise above ambient, well within the +85°C max operating TJ limit.