Microchip Technology MIC24085CYML-TX

Overview

MIC24085CYML-TX from Micrel is a 1.8V fixed-output, 18V-input, 3A synchronous buck regulator with integrated high- and low-side MOSFETs, operating at 1MHz in constant-frequency peak current-mode PWM. It delivers up to 3A output current with ±1.5% reference accuracy (0.9V), 4ms internal soft-start, and operates across –40°C to +125°C junction temperature for embedded power rails in networking gateways.

For engineers reviewing the MIC24085CYML-TX datasheet, MIC24085CYML-TX pinout, MIC24085CYML-TX application, or MIC24085CYML-TX equivalent, key selection criteria include its 1.8V fixed output, 16-pin 3mm × 3mm QFN package, 10µA shutdown current, PFM light-load mode, and integrated overcurrent/overtemperature protection - all critical for space-constrained, thermally demanding DC/DC designs.

Technical Context

The MIC24085CYML-TX implements peak current-mode control with internal slope compensation and fully integrated loop compensation, enabling stable operation with low-ESR ceramic output capacitors without external compensation components. Its architecture includes cycle-by-cycle current limiting and frequency foldback (1MHz → 250kHz) under overload, triggered when FB falls below 60% of 0.9V.

It integrates dual N-channel MOSFETs (135mΩ high-side, 90mΩ low-side), a 0.9V ±1.5% reference, open-drain power-good (PG) with 93–103% VOUT window and 11ms recovery hold time, and an enable input with 480mV hysteresis and internal pull-up - all optimized for fast transient response and robust fault handling in compact point-of-load applications.

Key Specifications

Pinout & Package

Package: 16-pin 3mm × 3mm QFN (ML) with exposed thermal pad (ePAD), RoHS-compliant Pb-free finish. Thermal resistance θJA = 68°C/W, θJC = 7.5°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output buck regulator applications.

Compared with MP2451DT-LF-Z and TPS54302DDCR, the MIC24085CYML-TX uniquely combines 3A capability, 1.8V fixed output, integrated PG, 10µA shutdown, and 3mm × 3mm QFN in a single package - making it optimal for thermally constrained, feature-complete 1.8V PoL applications where reliability and footprint are prioritized.

Availability

MIC24085CYML-TX is available at Aetrix Electronics and suitable for networking gateways, set-top boxes, and industrial printers requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for MIC24085CYML-TX 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 power management semiconductor company founded in 1978 and acquired by Microchip Technology in 2015. It specialized in high-performance, integrated power solutions for communications and industrial markets.

The MIC24085 family was designed as a cost-effective, high-density synchronous buck regulator platform targeting space-constrained, thermally demanding point-of-load applications in networking, consumer, and embedded systems - with emphasis on integration, reliability, and ease of use.

FAQ

What is the output voltage tolerance of the MIC24085CYML-TX over temperature and line conditions?

The MIC24085CYML-TX provides a fixed 1.8V output with ±1.5% accuracy over the full –40°C to +125°C junction temperature range and across 4.5V to 18V input voltage. This specification is guaranteed by the internal 0.9V reference (±1.5%) and resistor divider ratio, ensuring stable regulation in thermally aggressive environments like enclosed gateways or industrial enclosures where the MIC24085CYML-TX is commonly deployed.

Does the MIC24085CYML-TX require external feedback resistors for its 1.8V output?

No, the MIC24085CYML-TX is the fixed 1.8V variant of the MIC24085 family and does not require external feedback resistors. The FB pin is internally connected to the 0.9V reference and the output divider, so it must be left unconnected (NC) in this version. This simplifies layout and eliminates resistor tolerance errors - a key advantage of the MIC24085CYML-TX over adjustable variants like MIC24085AYML.

How does the power-good (PG) signal behave during startup and fault conditions for the MIC24085CYML-TX?

The MIC24085CYML-TX's PG pin is an open-drain output that pulls low until the output reaches 93% of 1.8V (1.674V), then transitions high after a brief delay. During faults - such as overvoltage (>103% of 1.8V), undervoltage (<93%), or thermal shutdown - PG pulls low and remains low for 11ms after recovery before reasserting high. This behavior enables safe sequencing in systems relying on the MIC24085CYML-TX for critical 1.8V rails.

What thermal management considerations apply to the MIC24085CYML-TX in a 3A continuous load scenario?

At 3A continuous load with 12V input and 1.8V output, the MIC24085CYML-TX dissipates ~1.2W. With θJA = 68°C/W, ambient temperature must stay below ~70°C to avoid exceeding the 125°C max junction temperature - requiring adequate copper area on the ePAD, multiple thermal vias to inner ground planes, and airflow or heatsinking if enclosed. The built-in 170°C thermal shutdown provides fail-safe protection if thermal design margins are exceeded.

Can the MIC24085CYML-TX operate with ceramic output capacitors only, and what is the minimum recommended value?

Yes, the MIC24085CYML-TX is designed for ceramic-only output capacitance due to its internally compensated peak current-mode architecture. The datasheet recommends ≥22µF total output capacitance (e.g., one 22µF X5R 1206 capacitor) placed close to the SW and PGND pins. Lower values may cause instability or excessive ripple; using ≥47µF improves transient response for burst-mode loads common in the MIC24085CYML-TX's target applications.