Microchip Technology MIC5249-3.0BMM

Overview

MIC5249-3.0BMM from Micrel is a 300mA, 3.0V fixed-output CMOS low-dropout (LDO) regulator with programmable power-on-reset (POR) delay, ±1.0% initial output accuracy, 340mV dropout at full load, and ultra-low 85µA quiescent current. It integrates an open-drain RESET output, CMOS-compatible ENABLE pin, active shutdown clamp, and noise-reduction bypass input-designed for battery-powered handheld devices requiring stable, low-noise voltage regulation.

For engineers reviewing the MIC5249-3.0BMM datasheet, MIC5249-3.0BMM pinout, MIC5249-3.0BMM application, or MIC5249-3.0BMM equivalent, key selection criteria include its MSOP-8 footprint, adjustable POR delay via external capacitor, ceramic-capacitor stability, thermal shutdown protection, and compatibility with noise-sensitive RF and digital baseband circuits.

Technical Context

The MIC5249-3.0BMM implements a CMOS-based LDO architecture with internal reference bypassing via CBYP pin and precision undervoltage monitoring on VOUT to drive the open-drain RESET output. Its POR delay is set by an external capacitor on the DELAY pin, sourcing 0.55µA to generate a programmable timeout before RESET deasserts.

It features zero-current shutdown mode (≤1µA), active-clamp discharge of VOUT during disable, and stable operation with ≥2.2µF ceramic output capacitors (ESR ≤300mΩ). The device maintains regulation down to zero load and achieves 65dB PSRR at 120Hz without requiring tantalum or electrolytic capacitors.

Key Specifications

Pinout & Package

Package: 8-pin MSOP (MM), 3.0mm × 3.0mm × 1.0mm body, exposed pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1826-3002E/MS and TLS850F3TAV50, the MIC5249-3.0BMM uniquely combines programmable POR delay, sub-100µA quiescent current, and dedicated noise-reduction bypass-making it optimal for space-constrained, battery-sensitive consumer electronics where timing flexibility and signal integrity are critical.

Availability

MIC5249-3.0BMM is available at Aetrix Electronics and suitable for cellular phones, fiber optic modules, PDAs, and industrial handheld scanners requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MIC5249-3.0BMM 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 semiconductor company specializing in analog, power management, and timing solutions before its acquisition by Microchip Technology in 2015.

The MIC5249 family was designed specifically for noise-critical, battery-powered portable electronics-emphasizing low dropout, ultra-low quiescent current, ceramic-capacitor compatibility, and integrated power-good signaling.

FAQ

What is the maximum input voltage for MIC5249-3.0BMM at 300mA output in MSOP-8 package?

The MIC5249-3.0BMM supports up to +6V absolute maximum input, but practical maximum depends on thermal limits. At TA = 50°C and 300mA load, the calculated max VIN is 4.56V to stay within 125°C junction temperature using θJA = 160°C/W. Derating is required above ambient or with reduced copper area.

Does MIC5249-3.0BMM require an external pull-up resistor on the RESET pin?

Yes, MIC5249-3.0BMM features an open-drain RESET output and requires an external pull-up resistor-typically to VIN or VOUT-to establish a valid logic-high level when no fault is present. Pull-up values between 10kΩ and 100kΩ are commonly used depending on rise-time and bus loading requirements.

Can MIC5249-3.0BMM operate stably with zero load current?

Yes, MIC5249-3.0BMM remains stable and in regulation with no load-a key differentiator from many LDOs. This capability is essential for applications like CMOS RAM keep-alive circuits or always-on monitoring functions where load current may drop to zero without disrupting regulation.

What capacitor value is needed on the DELAY pin to achieve a 200ms POR delay for MIC5249-3.0BMM?

Using IDELAY = 0.55µA and VDELAY = 1.4V, the required DELAY capacitor is CDELAY = TDELAY × IDELAY / VDELAY = 200ms × 0.55µA / 1.4V ≈ 78.6nF. A standard 82nF ceramic capacitor yields ~205ms delay and is recommended for this timing target.

Is the NC pin on MIC5249-3.0BMM electrically connected internally?

No, the NC (pin 6) on MIC5249-3.0BMM is not internally bonded and serves no electrical function. It must remain unconnected on the PCB layout-no trace, pad, or solder should be attached to this pin to avoid unintended coupling or mechanical stress.