Microchip Technology MIC5249-2.5BMM

Overview

MIC5249-2.5BMM from Micrel is a 300mA, 2.5V fixed-output CMOS low-dropout regulator with programmable power-on-reset 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 voltage rails.

For engineers reviewing the MIC5249-2.5BMM datasheet, MIC5249-2.5BMM pinout, MIC5249-2.5BMM application, or MIC5249-2.5BMM 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 MIC5249-2.5BMM 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 active-clamp shutdown discharges the output during disable, preventing residual bias in downstream circuitry.

Power-on-reset functionality is implemented via a precision 0.55µA current source into the DELAY pin, allowing delay time calculation using T_DELAY = C_DELAY × 1.4V / 0.55µA. The RESET output is open-drain, requires external pull-up, and asserts low only when both undervoltage condition and fault (overcurrent/thermal) coexist - eliminating false triggers.

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 TPS7A2025PDQNR and MCP1702T-2502E/MB, the MIC5249-2.5BMM uniquely integrates POR delay programming, open-drain RESET with intelligent fault logic, and reference bypass for ultra-low noise - making it the only option among the three that satisfies concurrent sequencing, fault reporting, and RF-grade cleanliness requirements.

Availability

MIC5249-2.5BMM is available at Aetrix Electronics and suitable for cellular phone baseband power, fiber optic transceiver bias, and portable medical sensor interface applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MIC5249-2.5BMM 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 and acquired by Microchip Technology in 2015. Known for high-performance power management and timing solutions.

The MIC5249 family was designed specifically for noise-critical, battery-powered portable electronics requiring precise, low-dropout regulation with integrated power sequencing and fault signaling - targeting handheld wireless devices and optical modules.

FAQ

What is the minimum input voltage required for stable operation of the MIC5249-2.5BMM?

The MIC5249-2.5BMM requires a minimum input voltage of 2.7V for guaranteed operation across temperature and load. With its 340mV typical dropout at 300mA, the device maintains regulation down to VIN = 2.84V under full load at room temperature. Below 2.7V, line regulation degrades and RESET may assert due to undervoltage detection. Always maintain VIN ≥ VOUT + dropout margin plus tolerance for worst-case conditions.

How is the power-on-reset delay time calculated for the MIC5249-2.5BMM?

The MIC5249-2.5BMM uses a 0.55µA current source into the DELAY pin to charge an external capacitor to a 1.4V threshold. Delay time is calculated as T_DELAY = (C_DELAY × 1.4V) / 0.55µA. For example, a 100nF capacitor yields ~255ms delay. No capacitor results in immediate RESET assertion - converting the output to a standard undervoltage flag without delay.

Does the MIC5249-2.5BMM require an external pull-up resistor on the RESET pin?

Yes, the MIC5249-2.5BMM RESET pin is an open-drain output and requires an external pull-up resistor to either VIN or VOUT. Typical values range from 10kΩ to 100kΩ. Without pull-up, the RESET signal cannot go high, disabling proper power sequencing. The output drives low only when both undervoltage and internal fault (overcurrent/thermal) conditions occur simultaneously.

Can the MIC5249-2.5BMM operate without an output capacitor?

No, the MIC5249-2.5BMM requires a minimum 2.2µF ceramic output capacitor for stability. Omitting it causes high-frequency oscillation and regulation failure. X7R or X5R dielectric types are recommended; maximum ESR must not exceed 300mΩ. The device remains stable at zero load, but output capacitance is mandatory for closed-loop control.

What is the function of the CBYP pin on the MIC5249-2.5BMM?

The CBYP pin on the MIC5249-2.5BMM connects to the internal voltage reference node. A 0.01µF ceramic capacitor from CBYP to GND reduces output voltage noise and improves PSRR by filtering reference fluctuations. Increasing capacitance further lowers noise but slightly increases turn-on time; the MIC5249-2.5BMM's quick-start circuit mitigates this trade-off.