Microchip Technology MIC4684-5.0BM

Overview

MIC4684-5.0BM from Micrel, Inc. is a fixed-output 5.0V, 2A continuous current buck switching regulator in an 8-lead Power-SO-8 package. It operates at 200kHz PWM with >85% efficiency across 4V–30V input, features internal compensation, thermal shutdown, over-current protection, and frequency-foldback short-circuit protection. It delivers stable 5.0V/2A output for embedded power rails in industrial control and point-of-load conversion.

For engineers reviewing the MIC4684-5.0BM datasheet, MIC4684-5.0BM pinout, MIC4684-5.0BM application, or MIC4684-5.0BM equivalent, key selection criteria include its fixed 5.0V output, 2A SO-8 capability without heatsink, 4V–30V wide-input operation, integrated NPN switch with bootstrap drive, and thermal/short-circuit safety features critical for reliable DC-DC design.

Technical Context

The MIC4684-5.0BM implements voltage-mode PWM control using a 1.235V bandgap reference and fixed-frequency 200kHz oscillator. Its internal NPN power switch is driven via a bootstrap capacitor (pin 4) to reduce saturation voltage (0.59V typ. @1A), enabling high efficiency without external gate drivers.

It integrates enable logic with TTL-compatible thresholds (2.0V on / 0.8V off), feedback sensing (pin 5), and dedicated ground pins (2,6,7) optimized for low-impedance thermal and EMI paths. Protection includes thermal shutdown at 160°C, cycle-by-cycle current limiting (2.2A short-circuit limit), and frequency foldback under hard short conditions.

Key Specifications

Pinout & Package

Package: 8-lead Power-SO-8 (SOP-8 M) with exposed die-attach paddle thermally connected to pins 2, 6, and 7 - provides θJA = 75°C/W (typ.) and θJC = 25°C/W for efficient heat transfer to PCB ground plane.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2678-5.0 and TPS54202D, the MIC4684-5.0BM uniquely combines fixed 5.0V output, 34V transient tolerance, and 2A capability in a standard SO-8 footprint - making it optimal for cost-sensitive, space-constrained 5V PoL applications requiring robustness across wide input and thermal ranges.

Availability

MIC4684-5.0BM is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and portable medical devices requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for MIC4684-5.0BM 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 MIC4684 family was designed as high-efficiency, thermally robust buck regulators targeting space-constrained industrial and automotive applications where SO-8 packaging, wide input range, and integrated protection were critical design requirements.

FAQ

What is the maximum continuous output current of the MIC4684-5.0BM at 85°C ambient temperature?

The MIC4684-5.0BM delivers 2A continuous output current at 60°C ambient per datasheet SOA curves. At 85°C ambient, derating applies: typical maximum continuous output is ~1.5A with adequate PCB copper area (≥6 cm² ground plane). Thermal performance depends on θJA, which varies with layout - always verify junction temperature using TJ = PD × θJC + TA.

Does the MIC4684-5.0BM require external feedback resistors to set the 5.0V output?

No. The MIC4684-5.0BM is a fixed-output variant with internal resistor divider connected to the FB pin, so no external resistors are needed for 5.0V regulation. This simplifies design, improves accuracy (±2%), and eliminates resistor tolerance drift effects - unlike adjustable versions such as MIC4684YM.

Can the MIC4684-5.0BM operate with a 3.3V input voltage?

No. The MIC4684-5.0BM has a minimum input voltage of 4.0V per Absolute Maximum Ratings and Operating Ratings. Operation below 4V is not guaranteed and may result in dropout or regulation failure. For sub-4V inputs, consider a different topology such as a buck-boost or LDO, or verify feasibility with Micrel's application notes on feed-forward diode configurations.

What is the purpose of the bootstrap capacitor (0.33µF/50V) on pin 4 of the MIC4684-5.0BM?

The bootstrap capacitor on pin 4 provides gate-drive voltage above VIN to fully saturate the internal NPN transistor, reducing V_CE(sat) from ~1.8V to 0.59V and increasing efficiency to >85%. It couples the AC switching waveform from SW (pin 1) to generate a DC-biased boost voltage - a critical element enabling high current in the SO-8 package without external drivers.

Is the MIC4684-5.0BM pin-compatible with other members of the MIC4684 family, such as the adjustable MIC4684YM?

Yes. All MIC4684 variants - including MIC4684-5.0BM, MIC4684YM (adjustable), and MIC4684BM (adjustable, Pb-free) - share identical 8-lead Power-SO-8 (M) pinout and mechanical footprint. However, FB pin behavior differs: fixed versions tie FB internally to output, while adjustable versions require external resistor dividers - PCB layout is compatible, but schematic design must match the variant's feedback architecture.