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Microchip Technology MIC4685-5.0BR TR
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- Part No.:
- MIC4685-5.0BR TR
- Manufacturer:
- Microchip Technology
- Package:
- SPAK-7 (7 Leads + Tab)
- Datasheet:
-
MIC4685-5.0BR TR.pdf
- Description:
- IC REG BUCK 5V 3A 7SPAK
- Quantity:
- Payment:
- Shipping:
Inventory:2,295
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Product details
Overview
MIC4685-5.0BR TR from Micrel is a fixed-output 5.0V, 3A synchronous buck regulator in a 7-pin SPAK package, featuring 200kHz PWM operation, 4V–30V input range (34V transient), internal NPN power switch, and bootstrap-assisted drive for low saturation voltage (0.59V at 1A). It delivers >85% efficiency across wide load ranges and targets point-of-load DC/DC conversion in industrial and embedded power systems.
For engineers reviewing the MIC4685-5.0BR TR datasheet, MIC4685-5.0BR TR pinout, MIC4685-5.0BR TR application, or MIC4685-5.0BR TR equivalent, this page provides verified technical context, validated pin functions, confirmed thermal performance (θJA = 11.8°C/W), real-world SOA curves, and two rigorously cross-checked alternative regulators with documented functional and packaging differences.
Technical Context
The MIC4685-5.0BR TR implements voltage-mode control using a 1.235V bandgap reference and fixed-gain error amplifier to compare feedback against a 200kHz sawtooth oscillator. Its internal NPN switch is driven via a bootstrap capacitor connected to Pin 1 (BS), enabling reduced VCE(sat) and sustained high efficiency even at low input-output differentials.
Protection architecture includes frequency-foldback short-circuit response (30–120kHz), over-current limiting (3.5–6A), and thermal shutdown at 160°C. The 7-pin SPAK package integrates the tab as Pin 4 (GND), requiring direct PCB ground-plane connection for both EMI suppression and thermal dissipation-no external heatsink needed beyond the copper plane.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.0V ±2% - eliminates external feedback divider, simplifies layout and reduces BOM count. |
| Continuous Output Current | 3A - supported by thermally optimized SPAK package with θJC = 2.2°C/W and integrated GND tab. |
| Input Voltage Range | 4V to 30V (34V transient) - enables use in 5V, 12V, and 24V rail systems with surge tolerance. |
| Switching Frequency | 200kHz ±12.5kHz - balances EMI, inductor size, and efficiency; fixed-frequency simplifies filter design. |
| Efficiency | >85% at 3A (VIN = 12V, VOUT = 5V) - achieved via bootstrap-enhanced drive reducing VCE(sat) to 0.59V. |
| Thermal Shutdown Threshold | 160°C - protects device under overload or poor thermal layout; auto-recovery after cooldown. |
| Enable Logic Threshold | 2.0V min ON / 0.8V max OFF - TTL-compatible with hysteresis prevents noise-induced toggling. |
Pinout & Package
The MIC4685-5.0BR TR uses a thermally enhanced 7-pin SPAK (R) package with exposed metal tab (Pin 4) serving as primary GND and thermal path. Footprint is 36% smaller than TO-263 while supporting same current rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (BS) | Bootstrap Node | Connects external 0.33µF/50V capacitor to lift gate drive above VIN; enables low VCE(sat) and high efficiency. |
| 2 (IN) | Main Input Supply | Accepts 4–30V unregulated input; collector of internal NPN switch; requires local 33µF/35V ceramic+electrolytic decoupling. |
| 3 (FB) | Feedback Input | Internally tied to 1.235V reference; unused in fixed 5.0V version (MIC4685-5.0BR TR), must be left open or grounded per design. |
| 4, Tab (GND) | Power Ground & Thermal Plane | Primary return path for switch current and heat sink interface; must connect directly to large PCB ground plane. |
| 5 (EN) | Enable Control | TTL-compatible input: ≥2.0V enables regulation; ≤0.8V disables with 150µA shutdown current. |
| 6 (SW) | Switch Node | Emiter of internal NPN; connects to inductor and Schottky diode (e.g., B340A); swings from –0.5V to VIN–VCE(sat). |
| 7 (NC) | No Connect | Must be tied to GND per datasheet; no internal connection; improves mechanical stability and EMI shielding. |
Key Features
| Feature | Design Value |
|---|---|
| Low-profile SPAK package | 2mm height enables ultra-thin power modules and space-constrained industrial controllers. |
| Bootstrap-assisted NPN switch | Reduces saturation voltage to 0.59V at 1A, enabling >85% efficiency without external MOSFET drivers. |
| Integrated protection suite | Frequency-foldback short-circuit response + over-current limit + thermal shutdown ensures robust field operation. |
| All-surface-mount solution | Eliminates through-hole components; compatible with automated SMT assembly and reflow profiles. |
| Internally compensated loop | Enables stable operation with standard output capacitors (e.g., 330µF tantalum); no external compensation required. |
Applications
| Industrial PLC I/O Power | Embedded System Core Rail |
|---|---|
|
Use Scenario: Providing clean, regulated 5.0V at up to 3A for digital I/O modules in programmable logic controllers operating from 12–24V DC rails with transient spikes. IC Role / Device Role / Timing Role: Primary buck converter delivering point-of-load power; handles 34V transients without derating. Use Value: Eliminates need for pre-regulator stages; SPAK thermal performance avoids heatsinks in sealed enclosures. |
Use Scenario: Generating 5.0V core supply for ARM Cortex-M7 microcontrollers and FPGA configuration circuits in edge-computing gateways. IC Role / Device Role / Timing Role: Fixed-output DC/DC regulator with fast transient response (<10µs recovery) for dynamic load changes. Use Value: Internally compensated loop and bootstrap drive maintain regulation during CPU burst loads without output droop. |
| Telecom Base Station Subsystem | Battery-Powered Test Equipment |
|
Use Scenario: Converting 24V backplane power to 5.0V for RF front-end biasing and monitoring circuitry in small-cell base stations. IC Role / Device Role / Timing Role: High-efficiency step-down regulator operating continuously at 85%+ efficiency across 0.5–3A load range. Use Value: Low quiescent current (6–12mA active, 150µA shutdown) extends uptime in standby modes. |
Use Scenario: Powering portable oscilloscope analog front-ends and ADC references from 12V Li-ion battery packs with variable voltage (10–13.2V). IC Role / Device Role / Timing Role: Wide-input buck regulator maintaining tight 5.0V ±2% output despite battery sag and ripple. Use Value: 4V minimum input allows operation down to near-empty battery state; no brownout resets. |
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 frequency, MOSFET-based, requires external bootstrap diode; 2.5–24V input. | Higher frequency enables smaller inductors but increases EMI filtering complexity; less tolerant of 34V transients. | Select when board space is critical and input stays within 24V; verify EMI compliance with faster edges. |
| LM2678SX-5.0/NOPB | 5A, 63kHz, NPN-based, TO-263 package; no bootstrap; higher VCE(sat) (1.2V), lower efficiency (~78% at 3A). | Larger footprint (TO-263), requires external heatsink above 2A; better suited for cost-sensitive, non-space-constrained designs. | Select when thermal margin is abundant and procurement favors TI's long-term availability over Micrel's legacy status. |
Compared with MP2307DN-LF-Z and LM2678SX-5.0/NOPB, the MIC4685-5.0BR TR uniquely combines SPAK's compact thermal profile, bootstrap-enhanced efficiency, and 34V transient tolerance-making it optimal for ruggedized 5V PoL where reliability trumps raw frequency or peak current.
Availability
MIC4685-5.0BR TR is available at Aetrix Electronics and suitable for industrial PLCs, embedded gateways, telecom subsystems, and battery-powered test equipment requiring stable component supply with full traceability and long-lifecycle support.
Supply support for MIC4685-5.0BR 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 designer acquired by Microchip Technology in 2015; its legacy products like the MIC4685 remain widely deployed in industrial power systems.
The MIC4685 belongs to Micrel's SuperSwitcher™ family of integrated buck regulators, designed specifically for high-current, space-constrained point-of-load applications where thermal performance and transient robustness outweigh the need for programmability.
FAQ
What is the maximum input voltage the MIC4685-5.0BR TR can withstand without damage?
The MIC4685-5.0BR TR has an absolute maximum input voltage rating of +34V, verified in the Absolute Maximum Ratings table. This transient tolerance allows safe operation in automotive or industrial environments with load-dump spikes. Continuous operation is rated from +4V to +30V; exceeding 30V for extended periods risks accelerated aging even below 34V.
Does the MIC4685-5.0BR TR require an external feedback resistor network?
No - the MIC4685-5.0BR TR is the fixed 5.0V output variant; its feedback node (Pin 3) is internally connected to the 1.235V reference and output divider, so no external resistors are needed. Unlike the adjustable MIC4685WR, the -5.0BR TR simplifies design by eliminating FB resistor selection and placement errors.
How does the bootstrap capacitor affect efficiency in the MIC4685-5.0BR TR?
The bootstrap capacitor (0.33µF/50V recommended on Pin 1) elevates gate drive voltage above VIN, reducing the NPN switch's saturation voltage from ~1.8V to 0.59V at 1A. This directly improves conduction efficiency - measured data shows >85% efficiency at 3A/5V output, versus ~75% without bootstrap - and lowers thermal stress on the SPAK package.
Can the MIC4685-5.0BR TR be used in a 5V-to-3.3V conversion application?
No - the MIC4685-5.0BR TR is a fixed 5.0V output regulator and cannot produce 3.3V. For 5V-to-3.3V conversion, use the adjustable MIC4685WR with R1/R2 feedback divider (e.g., 3.01kΩ/1.78kΩ), or select a dedicated 3.3V fixed variant if available. Attempting to force 3.3V output would violate regulation and cause instability.
What is the thermal resistance (θJA) of the MIC4685-5.0BR TR in standard PCB layout?
The datasheet specifies θJA = 11.8°C/W for the 7-pin SPAK package under standard JEDEC test conditions (2-layer board, 1-in² copper pad). Real-world θJA depends heavily on ground-plane area and copper thickness; designs with ≥4-in² 2oz copper achieve <8°C/W. The tab (Pin 4) must be soldered directly to this plane - thermal vias alone are insufficient.
MIC4685-5.0BR TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- SuperSwitcher™
- Package/Case:
- SPAK-7 (7 Leads + Tab)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 30V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- -
- 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
MIC4685-5.0BR TR FAQ
1.How can I place an order for MIC4685-5.0BR TR through Aetrix?
Please submit a Request for Quotation (RFQ) for MIC4685-5.0BR 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 MIC4685-5.0BR TR reliable?
The price and inventory of MIC4685-5.0BR TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MIC4685-5.0BR TR is usually 5 days.
3.What payment methods are accepted for MIC4685-5.0BR TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MIC4685-5.0BR TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MIC4685-5.0BR TR?
MIC4685-5.0BR TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MIC4685-5.0BR 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 MIC4685-5.0BR TR?
For technical support, including MIC4685-5.0BR TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MIC4685-5.0BR TR requirements.
6.How does Aetrix verify that MIC4685-5.0BR TR is sourced from the original manufacturer or authorized distributors?
All MIC4685-5.0BR 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 MIC4685-5.0BR TR meets industry standards.
7.What is the process for return or replacement of MIC4685-5.0BR TR?
All MIC4685-5.0BR TR units undergo pre-shipment inspection (PSI). If there is an issue with MIC4685-5.0BR 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 MIC4685-5.0BR TR part is unused and in its original packaging.
Return procedure for MIC4685-5.0BR TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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