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Microchip Technology MIC4685BR TR
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- Part No.:
- MIC4685BR TR
- Manufacturer:
- Microchip Technology
- Package:
- SPAK-7 (7 Leads + Tab)
- Datasheet:
-
MIC4685BR TR.pdf
- Description:
- IC REG BUCK ADJ 3A 7SPAK
- Quantity:
- Payment:
- Shipping:
Inventory:1,848
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Product details
Overview
MIC4685BR TR from Micrel is a 3A, 200kHz adjustable-output buck switching regulator in a thermally enhanced 7-pin SPAK package. It operates from 4V to 30V input (34V transient), delivers up to 3A continuous output current, and achieves >85% efficiency across wide load ranges - used in point-of-load DC/DC conversion for industrial power supplies and LCD bias rails.
For engineers reviewing the MIC4685BR TR datasheet, MIC4685BR TR pinout, MIC4685BR TR application, or MIC4685BR TR equivalent, key selection criteria include its bootstrap-enabled NPN switch architecture, 1.235V feedback reference, thermal shutdown at 160°C, frequency-foldback short-circuit protection, and compatibility with standard surface-mount PCB layouts requiring minimal heatsinking.
Technical Context
The MIC4685BR TR implements voltage-mode PWM control using a fixed 200kHz oscillator and internal 1.235V bandgap reference. Its NPN-based power stage uses external bootstrap capacitor coupling to raise gate drive above VIN, reducing saturation voltage to 0.59V and enabling high efficiency even at low VIN–VOUT differentials.
It integrates over-current protection with frequency foldback, thermal shutdown at 160°C, and TTL-compatible enable logic with 0.8V/2.0V hysteresis. The device requires no external compensation and supports adjustable output voltages via resistor divider on FB pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 30V DC (34V transient tolerant) - supports 12V/24V industrial rails and automotive battery inputs with surge margin. |
| Output Current | 3A continuous - sustained without derating when using SPAK package's 2.2°C/W θJC and adequate ground-plane heatsinking. |
| Switching Frequency | 200kHz ±12.5kHz - enables compact magnetics while minimizing EMI compared to higher-frequency alternatives. |
| Feedback Reference | 1.235V ±2% - sets output voltage via external resistor divider; stable over –40°C to +125°C junction temperature. |
| Efficiency | >85% typical at 1.5A–3A loads - achieved via bootstrap-enhanced NPN switch (VSAT = 0.59V) and low-quiescent-current design. |
| Protection Features | Thermal shutdown (160°C), frequency-foldback short-circuit protection, and over-current limiting (3.5–6A trip range). |
| Enable Threshold | Logic-high ≥2.0V, logic-low ≤0.8V - provides noise-immune TTL-compatible control with built-in hysteresis. |
Pinout & Package
The MIC4685BR TR is housed in a 7-pin SPAK (Small Power Air-cavity Package) with exposed thermal tab (Pin 4 and Tab). This thermally optimized surface-mount package offers 2.2°C/W junction-to-case resistance and replaces TO-220/TO-263 in space-constrained designs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (BS) | Bootstrap Node | Connects external boost capacitor to generate gate drive >VIN for NPN switch; critical for low VSAT and high efficiency. |
| 2 (IN) | Main Input Supply | Collector of internal NPN switch; accepts 4–30V unregulated input; must be decoupled near pin with low-ESR capacitor. |
| 3 (FB) | Feedback Input | Inverting input of error amplifier; tied to 1.235V reference; sets output voltage via resistive divider from VOUT. |
| 4 & Tab (GND) | Power Ground / Thermal Pad | Common return for switch, input cap, and output cap; exposed tab serves as primary thermal path to PCB ground plane. |
| 5 (EN) | Enable Control | TTL-compatible digital input; high = active regulation, low = shutdown (IQ ≈ 150µA); hysteresis prevents noise-induced toggling. |
| 6 (SW) | Switch Node | Emiter of internal NPN switch; connects to external inductor and Schottky diode; swings from –0.5V to VIN–VSAT during operation. |
| 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 |
|---|---|
| Bootstrap-driven NPN switch | Reduces saturation voltage to 0.59V, enabling >85% efficiency and eliminating need for external MOSFET drivers. |
| Internally compensated control loop | Enables stable operation with standard output capacitors; no external compensation components required for most applications. |
| Frequency-foldback short-circuit protection | Reduces switching frequency under hard short to limit energy per cycle and prevent thermal runaway without latch-off. |
| Wide input voltage range (4–30V) | Supports direct connection to 12V/24V systems and battery-powered equipment with transient immunity up to 34V. |
| Thermally enhanced SPAK package | Delivers 3A continuous current with only PCB ground plane as heatsink; 36% smaller footprint than TO-263. |
Applications
| Point-of-Load Conversion | LCD Panel Bias Supply |
|---|---|
Use Scenario: Converting 12V system rail to 3.3V/3A for FPGA I/O banks or microcontroller core logic in industrial controllers. IC Role / Device Role / Timing Role: Primary step-down regulator providing tightly regulated, low-noise DC output with fast transient response. Use Value: Delivers full 3A load with <1% load regulation and maintains >87% efficiency across 0.1–3A due to bootstrap-enhanced switch. |
Use Scenario: Generating 5V/2.5V/1.8V rails for TFT-LCD timing controllers and source/gate drivers in medical displays. IC Role / Device Role / Timing Role: Adjustable buck regulator configured for multiple outputs via resistor networks; supports dynamic voltage scaling. Use Value: Enables single-component solution for multi-rail LCD bias with thermal robustness up to +125°C ambient. |
| Battery Charger Front-End | Base Station Power Module |
Use Scenario: Stepping down 24V wall adapter or lead-acid battery output to 5V/3A for USB-C PD charging circuits. IC Role / Device Role / Timing Role: High-efficiency pre-regulator before linear post-regulation or battery management ICs. Use Value: Handles 34V transients common in automotive/battery systems and maintains regulation during cold-crank events. |
Use Scenario: Providing 3.3V/3A auxiliary power for RF front-end modules and clock distribution ICs in cellular base stations. IC Role / Device Role / Timing Role: Point-of-load regulator placed near RF section to minimize noise coupling and improve PSRR. Use Value: Low EMI layout and integrated protections ensure reliable operation in thermally dense telecom environments. |
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 synchronous buck; MOSFET-based; no bootstrap required; lower IQ (260µA vs 6mA typical) | Higher switching frequency enables smaller inductors but increases EMI sensitivity; less suitable for high-VIN–VOUT differential apps | Select MP2307DN-LF-Z when board space is constrained and input voltage ≤16V; avoid for 24V+ industrial inputs due to lower VIN rating (16V max). |
| LM2678SX-5.0/NOPB | 5A, 63kHz non-synchronous buck; NPN switch; similar 4–40V input range; requires external diode | Lower frequency allows larger, cheaper inductors; higher peak currents demand careful layout; no frequency foldback | Select LM2678SX-5.0/NOPB when cost-sensitive 5V-fixed output is needed and thermal design accommodates higher θJA; verify SOA for 3A continuous at high ambient. |
Compared with MP2307DN-LF-Z and LM2678SX-5.0/NOPB, the MIC4685BR TR uniquely balances high input voltage tolerance (30V), bootstrap-enhanced efficiency at low duty cycles, and integrated thermal/short-circuit protections - making it optimal for ruggedized 12V/24V embedded power where reliability trumps ultra-small size.
Availability
MIC4685BR TR is available at Aetrix Electronics and suitable for industrial motor drives, telecom power modules, and medical display systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging with high-melting solder exemption.
Supply support for MIC4685BR 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 mixed-signal semiconductor company founded in 1978 and acquired by Microchip Technology in 2015. Known for high-performance power management and timing solutions.
The MIC4685BR TR belongs to Micrel's SuperSwitcher™ family of integrated buck regulators, designed specifically for high-current, high-input-voltage DC/DC conversion in space- and thermally constrained industrial and telecom applications.
FAQ
What is the maximum continuous output current of the MIC4685BR TR?
The MIC4685BR TR delivers 3A continuous output current when mounted on a PCB with adequate ground-plane copper area acting as a heatsink. Its SPAK package has a junction-to-case thermal resistance of 2.2°C/W, and thermal shutdown activates at 160°C - allowing sustained 3A operation at ambient temperatures up to +60°C with proper layout per datasheet Figure 6.
Does the MIC4685BR TR require an external bootstrap diode?
No, the MIC4685BR TR does not require an external bootstrap diode. Its internal bootstrap circuit uses Pin 1 (BS) and an external ceramic capacitor (0.33µF recommended) to self-generate gate drive voltage above VIN. An external bootstrap diode is only needed in specialized low-headroom configurations (e.g., 5V→3.3V), and even then, it's optional per datasheet Section 12.
Can the MIC4685BR TR be used with input voltages above 30V?
The MIC4685BR TR has an absolute maximum input rating of +34V transient, but its specified operating range is +4V to +30V DC. Sustained operation above 30V violates the Absolute Maximum Ratings and risks permanent damage. For 36V+ systems, use input clamping or pre-regulation - the MIC4685BR TR itself must remain within 30V continuous.
What is the feedback reference voltage of the MIC4685BR TR?
The MIC4685BR TR features a precision 1.235V ±2% internal bandgap reference connected to the FB pin. This voltage sets the output via an external resistor divider (R1/R2), where VOUT = 1.235V × (1 + R1/R2). The reference remains stable across –40°C to +125°C and exhibits <10mV drift over input voltage range.
How does frequency foldback protection work in the MIC4685BR TR?
During output short-circuit conditions, the MIC4685BR TR reduces its switching frequency from 200kHz to as low as 30kHz (typical) to limit energy per switching cycle. This prevents thermal runaway while maintaining regulation attempt - unlike latch-off protection, it allows automatic recovery once fault clears, enhancing system resilience in intermittent-fault environments.
MIC4685BR 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:
- 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
MIC4685BR TR FAQ
1.How can I place an order for MIC4685BR TR through Aetrix?
Please submit a Request for Quotation (RFQ) for MIC4685BR 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 MIC4685BR TR reliable?
The price and inventory of MIC4685BR TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MIC4685BR TR is usually 5 days.
3.What payment methods are accepted for MIC4685BR TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MIC4685BR TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MIC4685BR TR?
MIC4685BR TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MIC4685BR 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 MIC4685BR TR?
For technical support, including MIC4685BR TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MIC4685BR TR requirements.
6.How does Aetrix verify that MIC4685BR TR is sourced from the original manufacturer or authorized distributors?
All MIC4685BR 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 MIC4685BR TR meets industry standards.
7.What is the process for return or replacement of MIC4685BR TR?
All MIC4685BR TR units undergo pre-shipment inspection (PSI). If there is an issue with MIC4685BR 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 MIC4685BR TR part is unused and in its original packaging.
Return procedure for MIC4685BR TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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