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Microchip Technology MIC4685WR-TR
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- Part No.:
- MIC4685WR-TR
- Manufacturer:
- Microchip Technology
- Package:
- SPAK-7 (7 Leads + Tab)
- Datasheet:
-
MIC4685WR-TR.pdf
- Description:
- IC REG BUCK ADJ 3A 7SPAK
- Quantity:
- Payment:
- Shipping:
Inventory:4,359
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Product details
Overview
MIC4685WR-TR from Micrel is a 3A adjustable-output synchronous buck regulator in a 7-pin SPAK package, operating at fixed 200kHz PWM with 4V–30V input range and 1.235V feedback reference. It delivers >85% efficiency across 0.1A–3A load, features internal NPN switch with bootstrap-enhanced drive (VSAT = 0.59V), and supports point-of-load conversion such as 12V-to-1.8V/3A for embedded power rails.
For engineers reviewing the MIC4685WR-TR datasheet, MIC4685WR-TR pinout, MIC4685WR-TR application, or MIC4685WR-TR equivalent, key selection criteria include its thermal performance (θJC = 2.2°C/W), frequency-foldback short-circuit protection, enable-input hysteresis (0.8V/2.0V thresholds), and compatibility with standard Schottky diodes and 39µH inductors in compact layouts.
Technical Context
The MIC4685WR-TR implements voltage-mode control using a 1.235V bandgap reference and 200kHz sawtooth oscillator to generate variable-duty-cycle gate drive for its internal NPN power switch. Bootstrap capacitor coupling at Pin 1 raises gate drive above VIN, reducing saturation voltage and enabling high efficiency even at low VIN–VOUT headroom.
It integrates over-current protection with foldback (30–120kHz under short-circuit), thermal shutdown at 160°C, and TTL-compatible enable logic with 150µA shutdown current. The ground tab (Pin 4 + exposed pad) serves dual EMI and thermal roles, requiring direct PCB ground plane connection for both regulation stability and heat dissipation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 30V DC (34V transient tolerant); supports automotive and industrial unregulated rails without external pre-regulation. |
| Output Current | 3A continuous; sustained via thermally optimized SPAK package with θJA = 11.8°C/W on standard 2oz copper ground plane. |
| Switching Frequency | Fixed 200kHz ±12.5%; enables predictable EMI filtering and use of standard 39µH shielded inductors. |
| Feedback Reference | 1.235V ±2% (–40°C to +125°C); sets output via external resistor divider; enables precise 1.8V/2.5V/3.3V/5V generation. |
| Saturation Voltage | 0.59V at 1A; reduced by bootstrap drive to minimize conduction loss and improve full-load efficiency beyond 85%. |
| Protection Features | Frequency-foldback short-circuit, thermal shutdown (160°C), and over-current limit (3.5–6A); prevents latch-up during fault conditions. |
| Enable Thresholds | UVLO hysteresis: 0.8V (off) / 2.0V (on); ensures noise-immune startup and clean shutdown without external RC filtering. |
Pinout & Package
The MIC4685WR-TR uses a 7-pin SPAK (R) package with exposed thermal tab (Pin 4 + metal pad), offering 2mm profile and 36% smaller footprint than TO-263. Thermal resistance is θJC = 2.2°C/W, requiring direct soldering of the tab to a large PCB ground plane for heatsinking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BS (Pin 1) | Bootstrap node | Connects external 0.33µF capacitor to SW pin; generates boosted gate drive voltage to reduce NPN saturation loss. |
| IN (Pin 2) | Main supply input | Collector of internal NPN switch; accepts 4–30V input; requires local 33µF/35V ceramic+electrolytic decoupling. |
| FB (Pin 3) | Feedback input | Connects to center tap of R1/R2 divider; compares output to 1.235V reference to regulate VOUT dynamically. |
| GND (Pin 4 + Tab) | Power and thermal ground | Common return for switch, input cap, and output cap; must be low-impedance copper plane for regulation stability and thermal management. |
| EN (Pin 5) | Enable control | TTL-compatible logic input; high ≥2.0V enables regulation; low ≤0.8V disables with 150µA quiescent current. |
| SW (Pin 6) | Switch emitter output | Drives external inductor and Schottky diode; swings from –0.5V to VIN–VSAT; requires tight layout to minimize ringing. |
| NC (Pin 7) | No-connect | Internally unconnected; must be tied to GND per datasheet to prevent floating node EMI or latch-up risk. |
Key Features
| Feature | Design Value |
|---|---|
| SPAK thermal packaging | 7-pin surface-mount package with exposed tab achieves θJC = 2.2°C/W - replaces TO-220/TO-263 in space-constrained designs. |
| Bootstrap-assisted switching | External capacitor at BS pin elevates gate drive, lowering VSAT from 1.8V to 0.59V and sustaining >85% efficiency down to 1.8V output. |
| Integrated safety logic | Combined frequency-foldback (30–120kHz), thermal shutdown (160°C), and current limiting eliminate need for external fault management circuitry. |
| Internally compensated loop | Stable operation with standard 39µH inductor and 330µF output capacitor - no external compensation components required. |
| Wide input transient tolerance | Rated for 34V transients on IN pin - suitable for 24V industrial systems with load-dump spikes without external TVS. |
Applications
| Point-of-Load Power Supply | Industrial 12V-to-5V Conversion |
|---|---|
Use Scenario: Local regulation for FPGA I/O banks or microcontroller cores on dense PCBs with limited board area. IC Role / Device Role / Timing Role: Primary buck regulator delivering stable 1.8V/3A or 2.5V/3A from intermediate 5V or 12V rail. Use Value: SPAK's low 2mm height and 36% smaller footprint vs. TO-263 enables routing under connectors and beneath BGA packages. |
Use Scenario: Converting 12V factory bus to 5V for PLC I/O modules, motor drivers, or sensor interfaces. IC Role / Device Role / Timing Role: High-current step-down regulator supporting 3A continuous load with <1% load regulation over temperature. Use Value: Built-in frequency foldback and thermal shutdown ensure reliable operation during momentary overloads common in industrial actuation. |
| Battery Charger Auxiliary Rail | LCD Panel Backlight Driver |
Use Scenario: Generating 3.3V auxiliary supply for charging controller logic and communication ICs in Li-ion battery packs. IC Role / Device Role / Timing Role: Adjustable buck converter powered from battery pack (8–30V) with enable-controlled sequencing. Use Value: 150µA shutdown current extends standby battery life; wide input range accommodates varying cell count configurations. |
Use Scenario: Providing regulated 5V or 3.3V for LCD timing controllers and interface ICs in portable medical displays. IC Role / Device Role / Timing Role: Compact, low-noise power source with fast transient response to support dynamic backlight dimming commands. Use Value: Internally compensated loop and 200kHz fixed frequency simplify EMI filter design while maintaining <100mV output ripple. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2307DN-LF-Z | 3A, 2MHz switching, MOSFET-based, 4.5–26V input; lacks bootstrap drive and has higher quiescent current (250µA). | Higher frequency allows smaller inductors but increases EMI sensitivity; less suitable for low-headroom 5V-to-3.3V conversion. | Prefer MIC4685WR-TR when VIN–VOUT headroom <2.5V or thermal budget is constrained - SPAK outperforms SO-8 in θJC. |
| LM2596T-ADJ | 3A, 150kHz, bipolar switch, 4–40V input; no frequency foldback, higher VSAT (~1.2V), larger TO-220 package. | Requires external heatsink above 1.5A; unsuitable for high-density layouts where SPAK's 2mm profile is critical. | Choose MIC4685WR-TR for space-constrained designs needing >85% efficiency at full 3A load without mechanical heatsinking. |
Compared with MP2307DN-LF-Z and LM2596T-ADJ, the MIC4685WR-TR delivers superior thermal performance (θJC = 2.2°C/W), lower conduction loss via bootstrap drive, and integrated short-circuit foldback - making it optimal for industrial and embedded applications demanding reliability at full rated current.
Availability
MIC4685WR-TR is available at Aetrix Electronics and suitable for point-of-load power supplies, industrial 12V-to-5V conversion, and battery charger auxiliary rails requiring stable component supply with long-term lifecycle assurance.
Supply support for MIC4685WR-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 analog and power IC manufacturer founded in 1978 and acquired by Microchip Technology in 2015; known for high-reliability regulators, Ethernet PHYs, and timing solutions.
The MIC4685WR-TR belongs to Micrel's SuperSwitcher™ family of integrated buck regulators, designed specifically for high-current, space-constrained DC-DC conversion in industrial, telecom, and embedded systems where thermal efficiency and layout simplicity are critical.
FAQ
What is the maximum continuous output current of the MIC4685WR-TR?
The MIC4685WR-TR delivers 3A continuous output current when properly mounted on a PCB with adequate ground plane copper area. Its SPAK package achieves θJC = 2.2°C/W, enabling full 3A operation up to +60°C ambient with 12V input and 5V output - verified in the "Typical Safe Operating Area" curves on page 8 of the datasheet. Derating applies above this ambient temperature.
Does the MIC4685WR-TR require an external bootstrap diode?
No, the MIC4685WR-TR does not require an external bootstrap diode. Its internal bootstrap circuit uses Pin 1 (BS) and an external 0.33µF capacitor referenced to Pin 6 (SW) to generate elevated gate drive. A bootstrap diode is only needed in specialized low-headroom configurations (e.g., 5V-to-3.3V), and even then, it connects externally - not within the MIC4685WR-TR itself.
What is the feedback reference voltage and tolerance of the MIC4685WR-TR?
The MIC4685WR-TR uses a precision 1.235V bandgap reference at the FB pin, with ±2% tolerance over –40°C to +125°C junction temperature. This value is confirmed in the "Electrical Characteristics" table (page 5), where min/typ/max values are 1.210V/1.235V/1.260V at TA = 25°C and 1.186V/1.235V/1.297V across full temperature range.
Can the MIC4685WR-TR operate with a 34V input transient?
Yes, the MIC4685WR-TR is rated for 34V absolute maximum input voltage per the "Absolute Maximum Ratings" table (page 4). It safely handles 34V transients on the IN pin without damage or latch-up, making it suitable for 24V industrial systems subject to load-dump events - no external TVS diode is required for this level of protection.
How does the enable pin (EN) function on the MIC4685WR-TR?
The EN pin on the MIC4685WR-TR provides TTL-compatible logic control: a voltage ≥2.0V (with hysteresis) enables regulation, while ≤0.8V disables it, reducing quiescent current to 150µA typical. This behavior is documented in the "Electrical Characteristics" table and "Enable Input Logic Level" section (page 5), and the pin must be tied to VIN if unused.
MIC4685WR-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- SuperSwitcher™
- Package/Case:
- SPAK-7 (7 Leads + Tab)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 30V
- Voltage - Output (Min/Fixed):
- 1.235V
- Voltage - Output (Max):
- 28.2V
- Current - Output:
- 3A
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 7-SPAK
MIC4685WR-TR FAQ
1.How can I place an order for MIC4685WR-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for MIC4685WR-TR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MIC4685WR-TR reliable?
The price and inventory of MIC4685WR-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MIC4685WR-TR is usually 5 days.
3.What payment methods are accepted for MIC4685WR-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MIC4685WR-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MIC4685WR-TR?
MIC4685WR-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MIC4685WR-TR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MIC4685WR-TR?
For technical support, including MIC4685WR-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MIC4685WR-TR requirements.
6.How does Aetrix verify that MIC4685WR-TR is sourced from the original manufacturer or authorized distributors?
All MIC4685WR-TR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MIC4685WR-TR meets industry standards.
7.What is the process for return or replacement of MIC4685WR-TR?
All MIC4685WR-TR units undergo pre-shipment inspection (PSI). If there is an issue with MIC4685WR-TR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MIC4685WR-TR part is unused and in its original packaging.
Return procedure for MIC4685WR-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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