Microchip Technology MIC4684-5.0BM TR

Overview

MIC4684-5.0BM TR from Micrel, Inc. is a fixed-output 5.0V, 2A continuous current synchronous buck 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 output for embedded power rails in industrial control modules.

For engineers reviewing the MIC4684-5.0BM TR datasheet, MIC4684-5.0BM TR pinout, MIC4684-5.0BM TR application, or MIC4684-5.0BM TR equivalent, key selection criteria include its fixed 5.0V output, 2A capability at 60°C ambient, bootstrap-enhanced NPN switch saturation voltage (0.59V typ), integrated enable logic with 2.0V/0.8V thresholds, and SO-8 thermal performance (θJA = 75°C/W).

Technical Context

The MIC4684-5.0BM TR 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 on pin 4 to reduce V_CE(sat), enabling high efficiency without external heat sinking.

It integrates multiple safety functions: thermal shutdown at 160°C, cycle-by-cycle over-current detection, and frequency foldback during hard short-circuit conditions (reducing switching frequency to ~70kHz). The enable pin supports TTL-compatible logic control with 150µA shutdown current and built-in hysteresis (2.0V/0.8V thresholds).

Key Specifications

Pinout & Package

Package: 8-lead Power-SO-8 (SOP-8M), thermally enhanced with exposed die-attach paddle connected to pins 2, 6, and 7 (GND). Pins 2/6/7 must be soldered to ≥6 cm² PCB ground plane for thermal compliance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2678-5.0 and TPS54202DRT, the MIC4684-5.0BM TR offers superior thermal efficiency in SO-8 packaging, built-in frequency foldback for robust short-circuit handling, and zero external feedback components - making it optimal for cost-sensitive, thermally constrained 2A industrial power rails.

Availability

MIC4684-5.0BM TR is available at Aetrix Electronics and suitable for industrial control systems, automotive body electronics, point-of-load FPGA supplies, and portable medical diagnostics requiring stable component supply and long-term manufacturability.

Supply support for MIC4684-5.0BM 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 power management, timing, and interface ICs before its acquisition by Microchip Technology in 2015. Known for high-reliability analog products and SuperSwitcher™ DC-DC regulators.

The MIC4684 family was designed as high-efficiency, thermally robust buck regulators targeting space- and cost-constrained industrial and automotive applications where SO-8 packaging and integrated protection were critical.

FAQ

What is the maximum continuous output current of the MIC4684-5.0BM TR?

The MIC4684-5.0BM TR delivers 2A continuous output current at 60°C ambient temperature when mounted on a PCB with ≥6 cm² ground plane connected to pins 2, 6, and 7. At 25°C ambient, derating is not required; at higher ambient temperatures, output current must be reduced per the SOA curves in the datasheet. The MIC4684-5.0BM TR achieves this in an 8-lead Power-SO-8 package without external heatsinking.

Does the MIC4684-5.0BM TR require external feedback resistors?

No. The MIC4684-5.0BM TR is a fixed 5.0V output variant - its feedback pin (pin 5) is internally connected to the output, eliminating the need for external resistors. This simplifies layout, reduces component count, and improves stability versus adjustable versions. The MIC4684-5.0BM TR uses the same internal 1.235V bandgap reference as adjustable variants but routes it directly to set the output voltage.

What protection features does the MIC4684-5.0BM TR include?

The MIC4684-5.0BM TR integrates over-current protection, frequency-foldback short-circuit protection, and thermal shutdown at 160°C. During hard short-circuit conditions, it reduces switching frequency from 200kHz to ~70kHz to limit energy per cycle. The MIC4684-5.0BM TR also includes enable-input hysteresis (2.0V/0.8V thresholds) to prevent noise-induced toggling.

Can the MIC4684-5.0BM TR operate from a 5V input to deliver 5V output?

No - the MIC4684-5.0BM TR requires minimum headroom of ~2.5V between input and output (per datasheet Note 4). For 5V output, minimum input is ~7.5V. To support low-headroom applications like 5V→3.3V, a feed-forward diode configuration is recommended, but that applies only to adjustable versions - the MIC4684-5.0BM TR is fixed-output and not validated for such use.

What is the purpose of the bootstrap capacitor on pin 4 of the MIC4684-5.0BM TR?

The bootstrap capacitor (0.33µF/50V typical) on pin 4 (BS) generates a voltage higher than V_IN to fully saturate the internal NPN power switch, reducing V_CE(sat) from ~1.8V to 0.59V typ. This directly improves conversion efficiency (>85%) and thermal performance. Without it, the MIC4684-5.0BM TR cannot achieve rated output current or efficiency - the capacitor must be placed close to pin 4 with low-ESR ceramic construction.