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Microchip Technology MIC4685-5.0BR
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- Part No.:
- MIC4685-5.0BR
- Manufacturer:
- Microchip Technology
- Package:
- SPAK-7 (7 Leads + Tab)
- Datasheet:
-
MIC4685-5.0BR.pdf
- Description:
- IC REG BUCK 5V 3A 7SPAK
- Quantity:
- Payment:
- Shipping:
Inventory:1,240
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Product details
Overview
MIC4685-5.0BR from Micrel is a fixed-output 5.0V, 3A synchronous buck regulator in a thermally enhanced 7-pin SPAK package, operating at 200kHz with input voltage range 4V–30V (34V transient), >85% efficiency, and integrated NPN power switch. It delivers point-of-load power for industrial DC/DC conversion where compact size and high thermal performance are critical.
For engineers reviewing the MIC4685-5.0BR datasheet, MIC4685-5.0BR pinout, MIC4685-5.0BR application, or MIC4685-5.0BR equivalent, key selection considerations include its fixed 5.0V output, bootstrap-enhanced saturation voltage (0.59V @1A), thermal shutdown at 160°C, enable logic thresholds (0.8V/2.0V), and compatibility with standard Schottky diode-based external circuits.
Technical Context
The MIC4685-5.0BR implements voltage-mode PWM control using a 200kHz oscillator and internal 1.235V bandgap reference to regulate output via feedback resistor divider. Its NPN-based switching architecture relies on an external bootstrap capacitor to elevate gate drive above VIN, reducing VCE(sat) and sustaining high efficiency across load current (0.1A–3A).
Thermal management leverages the SPAK package's low θJA (11.8°C/W) and θJC (2.2°C/W), enabling operation up to +125°C junction temperature without heatsink-only PCB ground plane required. Protection includes frequency-foldback short-circuit response, over-current limiting (3.5–6A), and thermal shutdown.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.0V ±2% - eliminates external feedback resistors; supports direct 5V rail generation from 8–30V inputs. |
| Continuous Output Current | 3A - sustained delivery under full thermal limits with proper PCB ground plane heat sinking. |
| Input Voltage Range | 4V to 30V (34V transient) - accommodates automotive battery, industrial 24V, and wide-input legacy systems. |
| Switching Frequency | 200kHz ±12.5kHz - enables use of standard 39µH inductors and reduces EMI vs. higher-frequency alternatives. |
| Efficiency | >85% at 5V/3A (VIN=12V) - achieved via bootstrap-driven NPN switch with 0.59V saturation voltage, minimizing conduction loss. |
| Enable Thresholds | 0.8V (max) low-level / 2.0V (min) high-level - TTL-compatible control with 1.2V hysteresis prevents noise-induced toggling. |
| Thermal Shutdown | 160°C - protects against sustained overload or poor layout; automatic recovery after cooldown. |
| Quiescent Current | 150µA (shutdown) / 6–12mA (active) - low standby draw enables battery-backed or always-on applications. |
Pinout & Package
The MIC4685-5.0BR uses the 7-pin SPAK (R) package: surface-mount, low-profile (2mm height), thermally optimized with exposed metal tab (Pin 4 and Tab) serving as primary ground and heat path. Footprint is 36% smaller than TO-263 while delivering comparable thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (BS) | Bootstrap Node | Connects external 0.33µF/50V capacitor to generate boosted gate drive voltage; essential for low VCE(sat). |
| 2 (IN) | Main Input Supply | Accepts 4–30V unregulated input; connects directly to collector of internal NPN switch and internal regulator. |
| 3 (FB) | Feedback Input | Internally tied to 1.235V reference; unused in MIC4685-5.0BR (fixed 5V version); must be grounded per datasheet. |
| 4 & Tab (GND) | Power Ground / Thermal Pad | Primary return path for high-current switching loop and thermal interface; requires large copper pour for heat dissipation. |
| 5 (EN) | Enable Control | TTL-compatible digital input: ≥2.0V enables regulation; ≤0.8V disables with 150µA shutdown current. |
| 6 (SW) | Switch Node | Emitter of internal NPN transistor; connects to inductor and Schottky diode cathode; swings from –0.5V to VIN–VCE(sat). |
| 7 (NC) | No Connect | Internally unconnected; must be tied to GND per datasheet to ensure mechanical stability and EMI control. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 5.0V output | Eliminates external feedback resistors and associated layout sensitivity; simplifies BOM and improves production yield. |
| Bootstrap-enhanced NPN switch | Reduces saturation voltage to 0.59V @1A, enabling >85% efficiency at 3A without external MOSFET drivers. |
| Frequency-foldback protection | Automatically lowers switching frequency during short-circuit events to limit peak switch current and prevent thermal runaway. |
| Integrated thermal shutdown | Triggers at 160°C junction temperature and recovers autonomously-no external circuitry needed for overtemperature safety. |
| Wide input voltage range | Supports 4–30V operation with 34V transient tolerance, making it suitable for 12V/24V industrial and automotive auxiliary rails. |
| All-surface-mount solution | SPAK package enables fully automated assembly; no through-hole components required for core regulator function. |
Applications
| Industrial Point-of-Load Converter | 5V Rail Generator for Embedded Controllers |
|---|---|
Use Scenario: Converting 12V or 24V system bus to clean 5V for microcontrollers, sensors, and I/O peripherals in factory automation PLCs. IC Role / Device Role / Timing Role: Primary step-down regulator providing regulated 5V/3A output with fast transient response and minimal external components. Use Value: High efficiency (>85%) reduces thermal load in enclosed enclosures; SPAK package saves board space versus TO-263 alternatives. |
Use Scenario: Powering ARM Cortex-M or RISC-V SoCs requiring stable 5V supply with low ripple and robust start-up behavior. IC Role / Device Role / Timing Role: Fixed-output buck converter delivering precise 5.0V ±2% with enable-controlled sequencing and thermal margin. Use Value: Built-in enable hysteresis (0.8V/2.0V) ensures noise-immune power-up/down; no external UVLO needed. |
| Legacy System Voltage Translation | Industrial LCD Backlight Power Supply |
Use Scenario: Replacing aging linear regulators (e.g., 7805) in field-deployed equipment where 5V/2–3A is required from 8–30V inputs. IC Role / Device Role / Timing Role: Drop-in high-efficiency replacement for inefficient linear solutions, reducing heat sink requirements and energy waste. Use Value: Only PCB ground plane needed for thermal management-no heatsink or airflow required even at full 3A load. |
Use Scenario: Generating 5V bias for LED driver ICs and timing controllers in industrial HMI displays operating in ambient temperatures up to +70°C. IC Role / Device Role / Timing Role: Primary 5V supply with thermal shutdown and short-circuit foldback to survive display fault conditions. Use Value: 160°C thermal shutdown and frequency foldback protect against sustained LED string open/short faults. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678-5.0 | 5V fixed, 5A output, 260kHz, SO-8 package; higher current but larger footprint and higher quiescent current (50mA active). | Requires external heat sinking above 2A; less thermally efficient in compact layouts due to SO-8 θJA = 50°C/W. | Choose LM2678-5.0 only when >3A output or higher VIN max (40V) is required; MIC4685-5.0BR preferred for space-constrained 3A designs. |
| TPS5430-5.0 | 5V fixed, 3A, 500kHz, SO-8; uses external MOSFETs, higher switching loss, lower efficiency at 3A (~82% @12V→5V). | Needs external high-side/low-side FETs and gate drivers; more complex layout and BOM. | TPS5430-5.0 suits designs needing higher frequency for smaller inductors; MIC4685-5.0BR offers simpler, more thermally robust single-chip solution. |
Compared with LM2678-5.0 and TPS5430-5.0, the MIC4685-5.0BR provides superior thermal performance in minimal area via its SPAK package, higher efficiency at 3A due to bootstrap-driven NPN switch, and lower component count-making it optimal for space- and thermal-sensitive industrial converters.
Availability
MIC4685-5.0BR is available at Aetrix Electronics and suitable for industrial automation, embedded controller power, and legacy system upgrades requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging with high-melting solder exemption.
Supply support for MIC4685-5.0BR 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 semiconductor company founded in 1978 and acquired by Microchip Technology in 2015; known for high-reliability DC/DC regulators and timing solutions.
The MIC4685 family was designed specifically for high-current, thermally constrained point-of-load applications in industrial, telecom, and embedded systems-emphasizing simplicity, efficiency, and ruggedness over programmability.
FAQ
What is the output voltage tolerance of the MIC4685-5.0BR?
The MIC4685-5.0BR delivers a fixed 5.0V output with ±2% tolerance over temperature (–40°C to +125°C) and line/load conditions, as specified in the Electrical Characteristics table. This tight tolerance is maintained by the internal 1.235V bandgap reference and precision trimming-no external resistors affect accuracy since FB is internally configured for 5.0V.
Does the MIC4685-5.0BR require an external bootstrap diode?
No, the MIC4685-5.0BR does not require an external bootstrap diode. Its bootstrap circuit uses only an external 0.33µF/50V capacitor (CBS) connected between BS (Pin 1) and SW (Pin 6). The internal charge pump generates sufficient gate drive voltage to saturate the NPN switch-adding a diode is unnecessary and not recommended per the datasheet.
Can the MIC4685-5.0BR operate with a 5V input to produce 5V output?
No-the MIC4685-5.0BR requires minimum headroom of ~2.5V between input and output (per Note 4). With a 5V output, VIN must be ≥7.5V. Attempting 5V→5V violates the minimum duty cycle requirement and will result in regulation failure. For low-headroom applications, consider the adjustable MIC4685WR with bootstrap diode configuration.
What is the maximum continuous output current for the MIC4685-5.0BR at 25°C ambient?
At TA = 25°C with adequate PCB ground plane copper (≥4 in², 2 oz), the MIC4685-5.0BR sustains 3A continuously. Derating applies above 60°C ambient-see the Typical 5V Output SOA graph (page 8) which shows 3A supported up to ~24V input at TA = 60°C and TJ = 125°C.
How is the enable pin used in the MIC4685-5.0BR, and what happens when left floating?
The EN pin (Pin 5) must be actively driven: ≥2.0V enables regulation; ≤0.8V disables with 150µA shutdown current. If left floating, the internal pull-down is insufficient-unpredictable oscillation or partial turn-on may occur. Datasheet mandates tying EN to IN if unused; this ensures reliable enablement without external components.
MIC4685-5.0BR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- SuperSwitcher™
- Package/Case:
- SPAK-7 (7 Leads + Tab)
- Packaging:
- Bulk
- 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 FAQ
1.How can I place an order for MIC4685-5.0BR through Aetrix?
Please submit a Request for Quotation (RFQ) for MIC4685-5.0BR 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 reliable?
The price and inventory of MIC4685-5.0BR 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 is usually 5 days.
3.What payment methods are accepted for MIC4685-5.0BR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MIC4685-5.0BR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MIC4685-5.0BR?
MIC4685-5.0BR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MIC4685-5.0BR 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?
For technical support, including MIC4685-5.0BR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MIC4685-5.0BR requirements.
6.How does Aetrix verify that MIC4685-5.0BR is sourced from the original manufacturer or authorized distributors?
All MIC4685-5.0BR 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 meets industry standards.
7.What is the process for return or replacement of MIC4685-5.0BR?
All MIC4685-5.0BR units undergo pre-shipment inspection (PSI). If there is an issue with MIC4685-5.0BR, 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 part is unused and in its original packaging.
Return procedure for MIC4685-5.0BR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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