Microchip Technology MIC5318-1.5YMT-TR

Overview

MIC5318-1.5YMT-TR from Micrel is a fixed-output 1.5V ultra-low dropout (ULDO™) linear regulator delivering 300mA with 110mV dropout at full load, 30µV_RMS output noise, and ±2% initial accuracy - designed for RF-sensitive, battery-powered portable electronics requiring stable low-noise bias.

For engineers reviewing the MIC5318-1.5YMT-TR datasheet, MIC5318-1.5YMT-TR pinout, MIC5318-1.5YMT-TR application, or MIC5318-1.5YMT-TR equivalent, key selection criteria include its 1.6mm × 1.6mm Thin MLF® package, enable-controlled zero-current shutdown, ceramic-capacitor stability, and high PSRR (>70dB @ 1kHz) in RF power rail conditioning.

Technical Context

The MIC5318-1.5YMT-TR integrates a CMOS-based error amplifier, thermal shutdown, and current-limit protection within a fixed-output ULDO architecture optimized for minimal voltage headroom and noise. Its quick-start bypass circuit enables fast turn-on (<35µs) even with a 0.01µF BYP capacitor.

It operates across 2.3V–6.0V input range with internal 1.25V reference, achieving regulation without load - critical for CMOS RAM keep-alive circuits - and maintains ±3% output accuracy over –40°C to +125°C junction temperature.

Key Specifications

Pinout & Package

Package: 6-pin 1.6mm × 1.6mm Thin MLF® (MT), exposed heatsink pad internally connected to GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS79515DRVR and NCP114AMX15T2G, the MIC5318-1.5YMT-TR delivers superior RF suitability via lower dropout (110mV vs. ≥170mV), lower noise (30µV_RMS vs. ≥40µV_RMS), and dedicated BYP pin - making it the preferred choice for noise-critical, high-current portable RF subsystems.

Availability

MIC5318-1.5YMT-TR is available at Aetrix Electronics and suitable for mobile phones, GPS receivers, and digital still cameras requiring stable component supply, RoHS-compliant packaging, and long-term industrial temperature support (–40°C to +125°C).

Supply support for MIC5318-1.5YMT-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 MIC5318 product line was engineered for ultra-low-noise, high-PSRR portable power regulation - targeting RF front-ends, battery-constrained imaging, and precision analog subsystems in consumer and industrial handheld equipment.

FAQ

What is the minimum input voltage required for MIC5318-1.5YMT-TR to maintain regulation at 300mA output?

The MIC5318-1.5YMT-TR requires a minimum input voltage of 1.61V to maintain regulation at 300mA, calculated as V_OUT + V_DROP = 1.5V + 0.11V. This ultra-low dropout enables operation from partially discharged single-cell Li-ion (2.7–4.2V) or NiMH (1.0–1.4V/cell) sources when stacked appropriately. The device remains functional down to 2.3V input per absolute rating, but regulation is guaranteed only above the dropout threshold.

Does MIC5318-1.5YMT-TR require an external bypass capacitor on the BYP pin for basic operation?

No, the MIC5318-1.5YMT-TR operates fully functional without a BYP capacitor. The BYP pin is optional: connecting a 0.01µF capacitor to GND reduces output noise from ~45µV_RMS to 30µV_RMS and improves PSRR, but omission does not affect regulation, stability, or enable functionality. It is recommended only for RF-sensitive applications like GPS receivers or cellular transceivers where noise performance is critical.

Can MIC5318-1.5YMT-TR be used with zero load current, and does it remain stable?

Yes, the MIC5318-1.5YMT-TR remains stable and in regulation with zero load current - a key differentiator from many LDOs. This no-load stability is essential for applications such as CMOS RAM keep-alive circuits, real-time clock backup supplies, or sensor bias rails that cycle between active and idle states. The internal compensation ensures loop stability across 0–300mA load range without external adjustments.

What is the thermal resistance (θ_JA) of MIC5318-1.5YMT-TR in its standard package, and how does it affect maximum ambient temperature?

The MIC5318-1.5YMT-TR in its 6-pin 1.6mm × 1.6mm Thin MLF® package has a junction-to-ambient thermal resistance (θ_JA) of 100°C/W under recommended minimum footprint layout. At 300mA load with 1.5V output and 3.3V input, power dissipation is ~0.54W; using T_J(MAX) = 125°C, the maximum allowable ambient temperature is 71°C. Adequate copper pour on the exposed pad is essential to achieve this θ_JA value.

Is MIC5318-1.5YMT-TR compatible with X5R or Y5V ceramic output capacitors, or is X7R mandatory?

X7R ceramic capacitors are recommended for MIC5318-1.5YMT-TR due to their ±15% capacitance tolerance over –55°C to +125°C, ensuring stable regulation across temperature. X5R is acceptable but exhibits greater drift (~±15% over –55°C to +85°C). Y5V is not recommended - its capacitance can drop by up to 60% over temperature, risking instability or excessive ripple. A minimum 1µF X7R capacitor is required for guaranteed stability per the datasheet.