Microchip Technology MIC5259-4.75BML-TR

Overview

MIC5259-4.75BML-TR from Micrel is a 300mA, 4.75V fixed-output CMOS low-dropout regulator in a 6-pin 2mm × 2mm MLF® package, delivering 1.5% initial output accuracy, 300mV dropout at full load, and ultra-low 30µV(rms) output noise - optimized for RF power rails in battery-powered handheld devices.

For engineers reviewing the MIC5259-4.75BML-TR datasheet, MIC5259-4.75BML-TR pinout, MIC5259-4.75BML-TR application, or MIC5259-4.75BML-TR equivalent, key selection criteria include PSRR (70dB @ 1kHz), enable-input logic compatibility (VIH = 1.6V, VIL = 0.4V), ceramic-capacitor stability (1µF min COUT), thermal shutdown (150°C), and low-quiescent current (105µA at light load).

Technical Context

The MIC5259-4.75BML-TR employs a CMOS pass element with active-clamp shutdown and quick-start bypass control to achieve fast transient response and controlled turn-off discharge. Its internal reference is decoupled via the dedicated BYP pin, enabling noise reduction through external 0.01µF–1.0µF capacitors.

It operates across 2.7V–6.0V input range with TTL-compatible enable logic, tight line regulation (±0.3%/V), and load regulation (0.6–3.0%) over 0.1mA–300mA. Thermal protection includes 150°C shutdown with 10°C hysteresis and junction-to-ambient thermal resistance of 90°C/W in the MLF® package.

Key Specifications

Pinout & Package

Package: 6-pin 2mm × 2mm MLF® (exposed thermal pad), RoHS-compliant, Pb-free, moisture-sensitive level 3.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise LDO applications.

Compared with TPS79547DBVR and NCP1117ST4.75T3G, the MIC5259-4.75BML-TR uniquely combines 4.75V precision, 300mV dropout, 30µV(rms) noise, and MLF® thermal performance - making it the sole option among the three qualified for RF-sensitive, space-constrained, battery-operated systems.

Availability

MIC5259-4.75BML-TR is available at Aetrix Electronics and suitable for cellular transceiver power, portable medical sensor bias, laptop USB-C PD interface, and industrial handheld scanner applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MIC5259-4.75BML-TR 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 MIC5259-4.75BML-TR belongs to Micrel's µCap CMOS LDO family, engineered specifically for ultra-low-noise, high-PSRR regulation in battery-powered RF and portable instrumentation systems.

FAQ

What is the minimum input voltage required for MIC5259-4.75BML-TR to maintain regulation?

The MIC5259-4.75BML-TR requires a minimum input voltage of 2.7V per its operating rating, but to sustain 4.75V output at 300mA load, VIN must exceed VOUT + dropout - i.e., ≥5.05V (4.75V + 300mV). At lighter loads, regulation holds down to VIN = 4.75V + 150mV due to reduced dropout. The absolute minimum VIN is 2.7V, though output will drop out below that threshold.

Can MIC5259-4.75BML-TR operate without the BYP capacitor?

Yes, the MIC5259-4.75BML-TR functions without the BYP capacitor, but output noise increases from 30µV(rms) to approximately 120µV(rms), and PSRR degrades significantly above 100Hz. The BYP pin may be left open per datasheet, but omitting the 0.01µF capacitor forfeits the device's ultra-low-noise capability - essential for RF and precision analog applications where the MIC5259-4.75BML-TR is typically deployed.

Is MIC5259-4.75BML-TR compatible with X5R ceramic output capacitors?

Yes, the MIC5259-4.75BML-TR is explicitly characterized and stabilized for use with X5R and X7R dielectric ceramic capacitors ≥1µF. X5R types are acceptable and widely used; however, their capacitance can vary up to ±15% over temperature, so design margin should account for worst-case COUT reduction. Y5V/Z5U dielectrics are not recommended due to >50% capacitance loss over temperature, risking instability.

Does MIC5259-4.75BML-TR have reverse current protection?

No, the MIC5259-4.75BML-TR does not integrate reverse current protection. If VOUT exceeds VIN (e.g., during hot-swap or backup-battery scenarios), current can flow backward from OUT to IN through the pass device's intrinsic body diode. External protection - such as a series Schottky diode or ideal diode controller - is required in systems where reverse voltage or backfeed is possible.

What is the thermal performance difference between MIC5259-4.75BML-TR and the SOT-23-5 variant?

The MIC5259-4.75BML-TR in the 2mm × 2mm MLF® package has θJA = 90°C/W (minimum footprint), versus 235°C/W for the SOT-23-5 version. This means the MLF® variant dissipates heat 2.6× more effectively: at 300mA and 5.5V input, power dissipation is ~810mW, resulting in ~73°C junction rise above ambient for the MLF® vs. ~190°C for SOT-23-5 - making the MIC5259-4.75BML-TR viable for continuous 300mA operation in compact layouts where the SOT-23-5 would thermally shut down.