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Microchip Technology MIC4684BM
- Part No.:
- MIC4684BM
- Manufacturer:
- Microchip Technology
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MIC4684BM.pdf
- Description:
- IC REG BUCK ADJ 2A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,324
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Product details
Overview
MIC4684BM from Micrel, Inc. is a 2A continuous-output, fixed-frequency (200 kHz) synchronous buck regulator in an 8-lead Power-SO-8 package, designed for step-down DC/DC conversion from 4V–30V input to adjustable 1.235V–30V output. It delivers >85% efficiency at 1.8V/2A and 5V/1.7A outputs with no external heat sink required, supporting applications including industrial power rails and battery-powered systems.
For engineers reviewing the MIC4684BM datasheet, MIC4684BM pinout, MIC4684BM application, or MIC4684BM equivalent, key selection criteria include its internal NPN switch architecture, bootstrap-driven saturation voltage reduction (0.59 V typ.), thermal shutdown at 160°C, frequency-foldback short-circuit protection, and compatibility with feed-forward diode configurations for low headroom operation (e.g., 5V→3.3V).
Technical Context
The MIC4684BM implements voltage-mode PWM control using a 1.235 V bandgap reference and fixed 200 kHz oscillator, with duty cycle adjusted via feedback error amplifier comparison against a sawtooth waveform. Its internal NPN pass transistor is driven by a bootstrap capacitor (pin 4) to reduce VCE(sat) and sustain high efficiency across load current (0.1–2 A) and input voltage (4–30 V) ranges.
Safety features include over-current protection with foldback (30–120 kHz under short circuit), thermal shutdown at 160°C, and input transient tolerance up to 34 V. Ground pins (2, 6, 7) are internally tied to a common die-attach paddle for low θJA (75°C/W typical) and enhanced thermal performance on PCB ground planes ≥6 cm².
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 2 A continuous at 60°C ambient; enables compact replacement of TO-220/TO-263 regulators |
| Input Voltage Range | 4 V to 30 V (34 V transient); supports wide-input industrial and automotive battery systems |
| Switching Frequency | Fixed 200 kHz ±25 kHz; balances EMI, inductor size, and efficiency without external timing components |
| Feedback Reference | 1.235 V ±2% bandgap; sets output voltage via external resistor divider (e.g., 1.8 V @ R1=3.01 kΩ, R2=6.49 kΩ) |
| Efficiency | >85% at 1.8 V/2 A (VIN=12 V); achieved via bootstrap-enhanced drive reducing VCE(sat) to 0.59 V |
| Thermal Shutdown | 160°C junction temperature; protects device during overload or poor heatsinking |
| Enable Threshold | 2.0 V min (ON), 0.8 V max (OFF); TTL-compatible logic control with 1.2 V hysteresis prevents noise-induced toggling |
Pinout & Package
Package: 8-lead Power-SO-8 (SOP-8 M) with integrated die-attach paddle connected to GND pins (2, 6, 7) for low thermal resistance (θJA = 75°C/W, θJC = 25°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SW) | Switch emitter node | Connects to inductor and Schottky diode cathode; swings from –0.5 V to VIN – VCE(sat); critical for layout to minimize loop inductance |
| 2, 6, 7 (GND) | Power and signal ground | Common connection to die paddle; must be tied to large PCB ground plane (≥6 cm²) for thermal management and low-EMI return path |
| 3 (IN) | Unregulated input supply | Collector of internal NPN switch; connect input capacitor cathode as close as possible to limit voltage spikes |
| 4 (BS) | Bootstrap voltage node | Drives external 0.33 µF capacitor to generate gate bias >VIN; enables low VCE(sat) and high efficiency |
| 5 (FB) | Feedback input | Compares output voltage (via resistive divider) to 1.235 V reference; high-impedance (50 nA bias) for precision regulation |
| 8 (EN) | Enable/disable control | TTL-compatible input; pulls regulator into 150 µA shutdown state when <0.8 V; tie to VIN if unused |
Key Features
| Feature | Design Value |
|---|---|
| Internal NPN power switch | Eliminates need for external MOSFET/driver; reduces BOM count and layout complexity in space-constrained designs |
| Bootstrap-driven saturation reduction | Lowers VCE(sat) from 1.8 V to 0.59 V, increasing efficiency from 75% to 88% and enabling 2 A output in SO-8 |
| Frequency-foldback short-circuit protection | Reduces switching frequency to ~70 kHz under hard short, limiting energy per cycle and preventing thermal runaway |
| Internally compensated error amplifier | Enables stable operation with minimal external components; supports fast transient response without loop compensation design |
| Feed-forward diode support | Allows direct VIN-to-BS biasing to further reduce headroom requirements (e.g., 5 V → 3.3 V), extending usable input range |
Applications
| Industrial Power Rail | Battery-Powered Equipment |
|---|---|
Use Scenario: Generating 3.3 V/1.7 A from 12 V rail in programmable logic controller (PLC) I/O modules. IC Role / Device Role / Timing Role: Primary step-down regulator supplying FPGA core and interface logic. Use Value: Delivers >87% efficiency at full load with no heat sink, reducing board area and thermal management cost. | Use Scenario: Converting 7.4 V Li-ion battery pack to 1.8 V/2 A for embedded microcontroller subsystem. IC Role / Device Role / Timing Role: Main DC/DC converter enabling ultra-low-power sleep modes and fast wake-up response. Use Value: Bootstrap + feed-forward configuration maintains regulation down to 4.2 V input, maximizing battery runtime. |
| Automotive Body Control | Test & Measurement Instrumentation |
Use Scenario: Providing 5 V/1.5 A from 9–16 V vehicle battery to sensor interface circuitry with cold-crank tolerance. IC Role / Device Role / Timing Role: Input-stable buck regulator handling 34 V transients and load-dump events. Use Value: Wide 4–30 V input range and 34 V absolute max rating ensure reliable operation during automotive electrical disturbances. | Use Scenario: Supplying clean 2.5 V/1.5 A to high-resolution ADC reference and analog front-end in portable DMM. IC Role / Device Role / Timing Role: Low-noise, tightly regulated power source minimizing measurement drift. Use Value: 1.235 V ±2% reference and <100 mV load regulation (0–1.5 A) ensure <0.1% output accuracy over temperature. |
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/NOPB | Fixed 5 V output; 5 A capability; requires external compensation; no bootstrap drive | Not adjustable; higher current but larger solution size and lower efficiency at light loads | Select when fixed 5 V output and higher peak current are required, and board space allows larger inductor/capacitor footprint |
| TPS54202DDCR | 2 A synchronous buck; 4.5–28 V input; 500 kHz switching; integrated MOSFETs; no bootstrap pin | Higher frequency enables smaller magnetics; lacks feed-forward diode support for ultra-low headroom | Select for higher switching frequency and better light-load efficiency, but verify thermal performance at 2 A continuous in SO-8 |
Compared with LM2678-5.0/NOPB and TPS54202DDCR, the MIC4684BM uniquely combines adjustable output, bootstrap-enhanced efficiency, and feed-forward diode compatibility in an SO-8 package-making it optimal for space-constrained, wide-input, low-headroom buck applications where thermal performance without a heatsink is critical.
Availability
MIC4684BM is available at Aetrix Electronics and suitable for industrial power rails, battery-powered equipment, automotive body control units, and test & measurement instrumentation requiring stable component supply and long-term lifecycle support.
Supply support for MIC4684BM 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 semiconductor company specializing in power management, analog, and RF solutions before its acquisition by Microchip Technology in 2015.
The MIC4684BM belongs to Micrel's SuperSwitcher™ family of high-efficiency buck regulators, engineered to deliver high current in small packages using proprietary bootstrap techniques and thermally optimized Power-SO-8 packaging.
FAQ
What is the maximum continuous output current of the MIC4684BM at 60°C ambient?
The MIC4684BM delivers 2 A continuous output current at 60°C ambient temperature when mounted on a PCB with ≥6 cm² ground plane area. This rating assumes proper thermal layout per the datasheet, including connection of pins 2, 6, and 7 to the ground plane. At 25°C ambient, the SOA curves indicate up to 2.5 A is achievable for 5 V output with VIN = 12 V.
Does the MIC4684BM require external compensation components?
No, the MIC4684BM features an internally compensated error amplifier, eliminating the need for external compensation networks. This simplifies design and reduces bill-of-materials count while maintaining stability across recommended output capacitor types (tantalum, ceramic, or polymer) and values (e.g., 330 µF for 1.8 V output). Layout best practices still apply for FB node routing.
How does the bootstrap capacitor function in the MIC4684BM circuit?
The bootstrap capacitor (typically 0.33 µF, 50 V) connects between BS (pin 4) and SW (pin 1) to generate a voltage higher than VIN, which drives the base of the internal NPN switch. This reduces VCE(sat) from ~1.8 V to 0.59 V, directly improving efficiency and enabling 2 A output in the SO-8 package. The capacitor is charged during the switch OFF time via the internal bootstrap diode.
Can the MIC4684BM operate with input voltages below 4 V?
No, the MIC4684BM has a minimum operating input voltage of 4 V as specified in its Absolute Maximum Ratings and Operating Ratings. Attempting to operate below this threshold may result in failure to start, unstable regulation, or undefined behavior. For sub-4 V inputs, alternative regulators such as the MIC2280 or Microchip's MCP16301 should be evaluated.
What is the purpose of the feed-forward diode in MIC4684BM designs?
The feed-forward diode (e.g., SS34) connects VIN directly to the BS pin to provide additional bias during low-input-voltage conditions, reducing minimum required headroom (e.g., enabling 5 V → 3.3 V conversion). This extends usable input range and improves efficiency at light loads, especially in battery-powered applications where input voltage drops over discharge cycles.
MIC4684BM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- SuperSwitcher™
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Discontinued at Digi-Key
- 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:
- 2A
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MIC4684BM FAQ
1.How can I place an order for MIC4684BM through Aetrix?
Please submit a Request for Quotation (RFQ) for MIC4684BM 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 MIC4684BM reliable?
The price and inventory of MIC4684BM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MIC4684BM is usually 5 days.
3.What payment methods are accepted for MIC4684BM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MIC4684BM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MIC4684BM?
MIC4684BM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MIC4684BM 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 MIC4684BM?
For technical support, including MIC4684BM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MIC4684BM requirements.
6.How does Aetrix verify that MIC4684BM is sourced from the original manufacturer or authorized distributors?
All MIC4684BM 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 MIC4684BM meets industry standards.
7.What is the process for return or replacement of MIC4684BM?
All MIC4684BM units undergo pre-shipment inspection (PSI). If there is an issue with MIC4684BM, 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 MIC4684BM part is unused and in its original packaging.
Return procedure for MIC4684BM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MIC4684BM Tags
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