Microchip Technology MCP1812AT-033/OT

Overview

MCP1812AT-033/OT from Microchip Technology is a 300 mA ultra-low quiescent current (250 nA typical) fixed 3.3V low-dropout linear regulator in SOT-23-5 package, featuring output discharge during shutdown, stable operation with 2.2 µF ceramic output capacitor, and input voltage range of 2.4V to 5.5V at full load - designed for energy harvesting and long-life battery-powered systems.

For engineers reviewing the MCP1812AT-033/OT datasheet, MCP1812AT-033/OT pinout, MCP1812AT-033/OT application, or MCP1812AT-033/OT equivalent, this page delivers verified electrical specs, thermal performance data, shutdown behavior, ceramic capacitor stability requirements, and real-world use cases in wearable and medical electronics.

Technical Context

The MCP1812AT-033/OT implements a PMOS pass transistor architecture enabling ultra-low dropout voltage (400 mV typical at 300 mA) and inherent reverse-current blocking. Its internal reference and error amplifier maintain ±4% output voltage accuracy across -40°C to +85°C junction temperature.

It integrates an active discharge transistor (RDCH = 100 Ω typical) tied to the SHDN pin, enabling rapid VOUT discharge when shutdown is asserted - a critical feature for systems requiring controlled power sequencing and zero-output leakage during sleep modes.

Key Specifications

Pinout & Package

Package: 5-Lead SOT-23 (SC-74A), 2.9 mm × 1.6 mm × 1.1 mm, exposed pad optional (not electrically connected in standard version).

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B332MR-G and RP111N331D-TR-F, the MCP1812AT-033/OT uniquely delivers integrated output discharge in the same footprint - simplifying design for battery-constrained systems needing deterministic power-off behavior without added MOSFETs or timing circuits.

Availability

MCP1812AT-033/OT is available at Aetrix Electronics and suitable for energy harvesting nodes, wearable health monitors, and hearing aid platforms requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for MCP1812AT-033/OT 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 leading provider of microcontroller, analog, FPGA, and power management solutions, serving industrial, automotive, communications, and consumer markets with vertically integrated silicon and software.

The MCP181X/12X family was engineered specifically for ultra-low-power, long-life battery and energy-harvesting applications - emphasizing nanoscale quiescent current, ceramic-capacitor compatibility, and robust shutdown behavior in miniature packages.

FAQ

What is the minimum input voltage required for MCP1812AT-033/OT to regulate 3.3V at 300 mA?

The MCP1812AT-033/OT requires a minimum input voltage of 3.7V to maintain regulation at 300 mA load, based on its typical 400 mV dropout voltage (VDROPOUT = V_IN – V_OUT). At lower loads, it can operate down to 2.4V input. This enables efficient use of single-cell Li-ion or LiFePO₄ batteries throughout their discharge curve. The MCP1812AT-033/OT datasheet specifies 2.4V as the absolute minimum for I_OUT ≤ 150 mA and 2.4V as the practical lower bound for full 300 mA capability.

Does MCP1812AT-033/OT require an external pull-up resistor on the SHDN pin?

Yes - the MCP1812AT-033/OT SHDN pin is active-low and does not include an internal pull-up. A 1 MΩ resistor to VIN is recommended per Microchip's typical application circuit to ensure reliable startup and prevent floating states. Without it, the device may fail to enable or exhibit erratic behavior during power-up. This requirement is explicitly documented in the MCP1812AT-033/OT functional block diagram and Figure 2-44 through 2-47.

Can MCP1812AT-033/OT be used with a 1 µF output capacitor instead of the specified 2.2 µF?

No - the MCP1812AT-033/OT is only guaranteed stable with ≥2.2 µF ceramic (X7R) output capacitance, as confirmed in the "Stable with Ceramic Output Capacitor" feature and Table 1-1 of the datasheet. Using 1 µF risks oscillation or poor transient response, especially at 300 mA load. The MCP1811X series supports 1 µF, but the MCP1812AT-033/OT is part of the 300 mA MCP1812X family requiring the larger value.

Is the NC pin on MCP1812AT-033/OT electrically connected internally?

No - Pin 3 (NC) on the MCP1812AT-033/OT is a true no-connect terminal with no internal bond wire or circuit connection. It must remain unconnected in both schematic and layout; grounding or routing it may compromise thermal performance or cause unintended coupling. This is confirmed in the "Pin Description" section (page 19) of the DS20006088C datasheet.

What is the thermal resistance (θ_JA) of MCP1812AT-033/OT in its SOT-23-5 package?

The MCP1812AT-033/OT in 5-Lead SOT-23 has a typical junction-to-ambient thermal resistance (θ_JA) of 184.82°C/W on a JEDEC-standard 4-layer FR4 board with 1 oz. copper. This value assumes standard PCB layout practices - no thermal vias or copper pour - and defines maximum power dissipation limits. For example, at 300 mA and 0.4V dropout, P_D = 120 mW yields ~22°C rise above ambient, well within the +85°C max junction rating. This θ_JA is explicitly listed in Table 6-1 of the MCP1812AT-033/OT datasheet.