Microchip Technology MIC4690YM

Overview

MIC4690YM from Micrel is an adjustable 500kHz synchronous buck regulator IC delivering up to 1A continuous output current in a power-enhanced SO-8 package. It operates across a wide 4V–30V input range, regulates output down to 1.23V via external resistor divider, and integrates internal compensation, overcurrent protection, frequency foldback, and thermal shutdown for robust DC/DC conversion in space-constrained industrial and embedded systems.

For engineers reviewing the MIC4690YM datasheet, MIC4690YM pinout, MIC4690YM application, or MIC4690YM equivalent, key selection considerations include its fixed 500kHz switching frequency, ±1% feedback reference accuracy, SO-8 thermal design with pins 5–8 as dedicated ground terminals, and compatibility with standard 18µH inductors and Schottky diodes in compact 12V-to-5V/3.3V/2.5V/1.8V designs.

Technical Context

The MIC4690YM implements voltage-mode PWM control using a 1.23V bandgap reference and a fixed-frequency 500kHz oscillator. Its error amplifier compares FB voltage against this reference to generate duty-cycle-modulated gate drive for the integrated NPN switch.

Thermal performance relies on the power-SO-8's monolithic ground paddle (pins 5–8), achieving θJC = 20°C/W and enabling 1A operation at TJ ≤ 125°C with ≥6 cm² PCB ground plane. Protection includes cycle-by-cycle current limiting (2.5A typical short-circuit limit), frequency foldback (220–300kHz under overload), and thermal shutdown at 160°C.

Key Specifications

Pinout & Package

The MIC4690YM is housed in a thermally enhanced 8-lead SOIC (SOP-8) package with exposed die-attach paddle electrically tied to pins 5–8 (GND). This configuration provides low θJC (20°C/W) and requires direct connection to a ≥6 cm² PCB ground plane for 1A operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP1584EN-LF-Z and LM2678SD-ADJ/NOPB, the MIC4690YM offers optimal balance of 1A capability, SO-8 compactness, integrated protections, and fixed-frequency predictability-making it ideal for cost-sensitive, space-constrained 5–12V input applications where 1A suffices and layout simplicity is prioritized.

Availability

MIC4690YM is available at Aetrix Electronics and suitable for industrial PLCs, cable modems, hard disk drives, and portable test equipment requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MIC4690YM 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 specializing in power management, timing, and interface ICs before its acquisition by Microchip Technology in 2015.

The MIC4690YM belongs to Micrel's SuperSwitcher™ family of integrated buck regulators, designed specifically to replace through-hole TO-220/TO-263 converters with compact, thermally optimized SO-8 solutions for mid-power industrial and communications applications.

FAQ

What is the minimum output voltage achievable with the MIC4690YM?

The MIC4690YM has a precision 1.23V ±1% internal feedback reference, enabling output voltages as low as 1.23V when configured with an appropriate external resistor divider. For example, setting R2 = 1.24kΩ and R1 = 0Ω yields exactly 1.23V output. Lower outputs require external amplification or different topology, as the FB pin cannot be driven below its reference voltage.

Does the MIC4690YM require an external Schottky diode, and why?

Yes, the MIC4690YM requires an external Schottky diode (e.g., SS24 or equivalent) connected between the SW pin and output rail. Because the IC integrates only the NPN switch-not a synchronous MOSFET-the diode provides the freewheeling path during the switch-off phase. A Schottky type is mandatory for low forward voltage and fast recovery to maintain efficiency and prevent reverse recovery losses.

How does the MIC4690YM handle thermal overload conditions?

The MIC4690YM incorporates thermal shutdown that activates at approximately 160°C junction temperature, halting switching until the die cools below hysteresis threshold (~140°C). During prolonged overload, frequency foldback reduces switching frequency from 500kHz to ~220kHz, lowering average power dissipation and delaying thermal trip-providing graceful degradation rather than abrupt failure.

Can the MIC4690YM operate from a 3.3V input supply?

No, the MIC4690YM has a minimum input voltage of 4V per its Absolute Maximum Ratings and Operating Ratings tables. Attempting operation below 4V will result in dropout, unstable regulation, or complete disablement. For 3.3V input applications, a different regulator such as a low-V_IN buck (e.g., TPS62130) or boost-buck architecture is required.

What is the recommended PCB layout practice for grounding the MIC4690YM?

Micrel specifies that pins 5–8 (all labeled GND) and the internal thermal paddle must connect to a single, uninterrupted PCB ground plane of minimum 6 cm² area. This plane should be placed directly beneath and extending outward from the package, with multiple vias to inner-layer ground planes. Splitting or narrow traces to these pins severely degrades thermal performance and can cause premature thermal shutdown at <1A load.