Microchip Technology MIC5249-2.8BMM

Overview

MIC5249-2.8BMM from Micrel is a 300mA, 2.8V fixed-output CMOS low-dropout (LDO) regulator with programmable power-on-reset (POR) delay and ultra-low noise performance. It delivers ±1.0% initial output accuracy, 340mV dropout at full load, and integrates an open-drain RESET output triggered by undervoltage detection. Designed for battery-powered handheld devices requiring stable, clean power rails.

For engineers reviewing the MIC5249-2.8BMM datasheet, MIC5249-2.8BMM pinout, MIC5249-2.8BMM application, or MIC5249-2.8BMM equivalent, key selection criteria include adjustable POR delay via external capacitor, 65dB PSRR at 120Hz, ceramic-capacitor stability, zero-current shutdown mode, and MSOP-8 thermal performance under 300mA load.

Technical Context

The MIC5249-2.8BMM implements a CMOS-based LDO architecture with internal reference bypass (CBYP pin), enabling sub-10µV_RMS output noise when paired with a 0.01µF ceramic capacitor. Its POR function uses a precision 0.55µA current source into the DELAY pin to set reset timeout via external capacitance.

It features active-clamp shutdown for rapid output discharge, thermal shutdown with hysteresis, foldback current limiting, and logic-compatible ENABLE input with <0.01µA leakage. The RESET output combines undervoltage monitoring with fault OR-ing (overcurrent/overtemperature/dropout), ensuring glitch-free assertion.

Key Specifications

Pinout & Package

Package: 8-pin MSOP (MM), 3mm × 3mm footprint, 0.65mm pitch, exposed pad optional for thermal enhancement.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1826-2802E/DB and XC6209F282MR-G, the MIC5249-2.8BMM uniquely integrates adjustable POR delay, open-drain RESET, and reference bypass - enabling single-chip power sequencing and ultra-low-noise operation without external components.

Availability

MIC5249-2.8BMM is available at Aetrix Electronics and suitable for cellular handsets, fiber optic modules, PDAs, and industrial sensor nodes requiring stable component supply across extended temperature ranges (–40°C to +125°C).

Supply support for MIC5249-2.8BMM 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

Micrel Inc. was a U.S.-based analog and mixed-signal semiconductor company founded in 1978, specializing in power management, timing, and interface solutions before its acquisition by Microchip Technology in 2015.

The MIC5249 family was designed specifically for noise-sensitive, battery-powered portable electronics - delivering high PSRR, ceramic-capacitor stability, and integrated power-on-reset in miniature MSOP packages.

FAQ

What is the maximum input voltage for MIC5249-2.8BMM at 300mA output in MSOP-8 package?

The MIC5249-2.8BMM supports up to +6V input per absolute maximum rating, but practical maximum depends on thermal limits. At TA = 50°C and 300mA load, junction-to-ambient thermal resistance (θJA = 160°C/W) limits VIN to ~4.56V to avoid thermal shutdown. Derating is required above ambient temperatures or with reduced PCB copper area.

How do I calculate the POR delay time for MIC5249-2.8BMM using the DELAY pin?

The MIC5249-2.8BMM uses a 0.55µA current source into the DELAY pin with a 1.4V threshold. Delay time is calculated as TDELAY = CDELAY × 1.4V / 0.55µA. For example, a 100nF capacitor yields ~255ms delay. No capacitor results in immediate RESET assertion after power-up.

Does MIC5249-2.8BMM require an input capacitor, and what type is recommended?

Yes - MIC5249-2.8BMM requires a minimum 1.0µF ceramic input capacitor from VIN to GND for stability. Low-ESR X7R or X5R dielectric types are recommended. Additional high-frequency NPO capacitors (e.g., 10nF) improve RF noise rejection in sensitive applications.

Can MIC5249-2.8BMM operate without any load connected to VOUT?

Yes - MIC5249-2.8BMM remains stable and in regulation with zero load current, unlike many LDOs that require minimum load. This makes it suitable for CMOS RAM keep-alive, RTC backup, and other ultra-low-power standby applications where load may be disconnected.

What is the purpose of the CBYP pin on MIC5249-2.8BMM, and how should it be used?

The CBYP pin on MIC5249-2.8BMM connects to the internal voltage reference and must be bypassed with a 0.01µF ceramic capacitor to GND to reduce output noise and improve PSRR. Increasing capacitance further lowers noise but slightly increases turn-on time; the quick-start circuit minimizes this penalty.