Microchip Technology MCP1811BT-025/LB

Overview

MCP1811BT-025/LB from Microchip Technology is an ultra-low quiescent current (250 nA typical) 150 mA low-dropout linear regulator with fixed 2.5 V output, 1.8–5.5 V input range, and 5 nA shutdown current - designed for energy harvesting and long-life battery-powered systems such as hearing aids and smart wearables.

For engineers reviewing the MCP1811BT-025/LB datasheet, MCP1811BT-025/LB pinout, MCP1811BT-025/LB application, or MCP1811BT-025/LB equivalent, this page delivers verified electrical specs, package mapping to 3-lead SOT-23, thermal performance data, and real-world design trade-offs versus alternatives in ultra-low-power LDO selection.

Technical Context

The MCP1811BT-025/LB implements a PMOS pass transistor architecture enabling ultra-low dropout voltage (400 mV typical at 150 mA) and stable operation with only 1.0 µF ceramic output capacitance. Its internal error amplifier and reference circuit maintain ±4% output accuracy over -40°C to +85°C junction temperature.

It features active shutdown control via SHDN pin with 5 nA typical supply current, no output discharge (B-series variant), and integrated overcurrent protection with foldback limiting (50 mA at R_LOAD = 1 Ω). The device operates without external compensation and supports dynamic load steps up to 150 mA with <100 mV transient deviation.

Key Specifications

Pinout & Package

Package: 3-Lead SOT-23 (SC-59), JEDEC MO-178AA, 2.92 mm × 1.3 mm × 1.0 mm body, exposed pad optional per variant - optimized for space-constrained wearable PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B252MR-G and ADP160ACBZ-2.5-R7, the MCP1811BT-025/LB uniquely delivers 5 nA shutdown current while retaining 150 mA capability and 1.8 V minimum input - making it the only option among the three for sub-µA duty-cycle systems powered by weak energy harvesters or primary lithium cells.

Availability

MCP1811BT-025/LB is available at Aetrix Electronics and suitable for energy harvesting nodes, medical hearing aids, and smart wearable watches requiring stable component supply with guaranteed long-term manufacturability.

Supply support for MCP1811BT-025/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 U.S.-based semiconductor company specializing in microcontrollers, analog devices, and timing solutions, with a strong focus on low-power and embedded control markets.

The MCP1811 family was engineered specifically for ultra-low-power battery and energy-harvesting applications - emphasizing nanoscale quiescent current, minimal external components, and robust operation across extreme temperature and load transients.

FAQ

What is the maximum output current of the MCP1811BT-025/LB?

The MCP1811BT-025/LB delivers up to 150 mA continuous output current under specified thermal conditions. This rating assumes adequate PCB copper area and ambient temperature ≤+85°C. At 150 mA, dropout voltage remains ≤600 mV, and ground current stays within 110 µA - ensuring predictable performance in compact, battery-powered designs where the MCP1811BT-025/LB serves as the main system regulator.

Does the MCP1811BT-025/LB include an output discharge function?

No, the MCP1811BT-025/LB does not include output discharge. As a "B"-suffix variant (MCP1811B), it omits the internal discharge transistor present in "A"-suffix parts like MCP1811AT-025/LB. When SHDN is pulled low, VOUT floats rather than discharging to GND - preventing unintended resets in systems where downstream circuitry must retain state during shutdown. This behavior is explicitly confirmed in Table 1 and functional block diagram of DS20006088C.

Which package does the MCP1811BT-025/LB use, and what are its thermal characteristics?

The MCP1811BT-025/LB uses the 3-lead SOT-23 (SC-59) package, with θ_JA = 211.33°C/W on a JEDEC-standard 4-layer FR4 board. This thermal resistance enables safe operation at 150 mA up to +85°C ambient when using standard 1 oz. copper and thermal vias. The package's 2.92 mm × 1.3 mm footprint supports high-density wearable layouts, and its pinout matches industry-standard SOT-23 footprints for drop-in compatibility in existing designs using the MCP1811BT-025/LB.

Can the MCP1811BT-025/LB operate from a 1.8 V input while delivering 2.5 V output?

No - the MCP1811BT-025/LB cannot regulate 2.5 V output from a 1.8 V input. Its minimum input voltage is defined as VR + V_DROPOUT(MAX), and with a 600 mV max dropout, the minimum valid input is 3.1 V. However, the 1.8 V lower limit in the datasheet applies only when output current is ≤50 mA and VR is ≤2.5 V - but even then, regulation fails below ~2.9 V. For 2.5 V output, practical VIN must be ≥3.1 V to ensure stability and accuracy across temperature and load, as confirmed in Table 4-1 and Figure 2-1.

Is a bypass capacitor required on the VIN pin of the MCP1811BT-025/LB?

Yes, a 1.0 µF ceramic (X7R) capacitor is required on the VIN pin, placed as close as possible to the device. This input capacitor stabilizes the regulator against source impedance and suppresses high-frequency noise from upstream converters or batteries. The datasheet specifies C_IN = C_OUT = 1.0 µF for all AC/DC characterization, and omitting it degrades PSRR (e.g., -50 dB drops significantly at 1 kHz) and increases susceptibility to line transients - directly impacting reliability in the MCP1811BT-025/LB's target applications.