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Microchip Technology MIC4681-3.3BM TR
- Part No.:
- MIC4681-3.3BM TR
- Manufacturer:
- Microchip Technology
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MIC4681-3.3BM TR.pdf
- Description:
- IC REG BUCK 3.3V 1A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,044
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Product details
Overview
MIC4681-3.3BM TR from Micrel is a fixed-output 3.3V, 200kHz voltage-mode buck regulator in SOP-8 package, delivering up to 1.4A continuous output current (2A peak) across 4V–30V input range with internal NPN switch, cycle-by-cycle current limiting, and thermal shutdown-designed for GSM battery chargers and compact high-efficiency DC/DC conversion.
For engineers reviewing the MIC4681-3.3BM TR datasheet, MIC4681-3.3BM TR pinout, MIC4681-3.3BM TR application, or MIC4681-3.3BM TR equivalent, key selection factors include its fixed 3.3V output, 200kHz switching frequency, 1.23V feedback reference, 2.1A minimum current limit, and power-SOP-8 thermal performance with dedicated ground pins 5–8.
Technical Context
The MIC4681-3.3BM TR implements voltage-mode control using a 200kHz oscillator and 1.23V bandgap reference to regulate output via duty-cycle adjustment of an integrated NPN switch. Feedback is sampled at the FB pin, requiring no external compensation due to internal frequency compensation.
It features cycle-by-cycle current limiting with 2.2–4.5A short-circuit protection, thermal shutdown at 160°C, and shutdown logic with 0.8V/1.25V thresholds. The power-SOP-8 package uses pins 5–8 as a unified ground plane for low θJC (20°C/W) and enhanced thermal dissipation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±2% - eliminates external feedback resistors; supports direct 3.3V rail generation. |
| Switching Frequency | 200kHz ±10% - enables use of standard off-the-shelf inductors (e.g., 68µH) and reduces EMI vs. higher-frequency alternatives. |
| Continuous Output Current | 1.4A at 3.3V/25°C - verified per SOA curves; derates with input voltage and ambient temperature. |
| Input Voltage Range | 4V to 30V - supports wide industrial and automotive battery inputs, including 12V and 24V systems. |
| Feedback Reference | 1.23V ±1% - precision bandgap reference used internally; not accessible externally on fixed-output variants. |
| Shutdown Current | 6µA typical when VSHDN = VIN - enables ultra-low-power standby in battery-powered applications. |
| Thermal Shutdown | 160°C junction - protects device during overload or poor PCB thermal design without external circuitry. |
Pinout & Package
Package: 8-lead SOP (M), also known as power-SOP-8, with exposed die-attach paddle thermally connected to pins 5–8 (all GND). Junction temperature range: –40°C to +125°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SHDN) | Shutdown control input | TTL-compatible logic input; <0.8V enables regulation, >1.4V disables with <6µA quiescent draw. |
| 2 (VIN) | Main power input | Accepts 4V–30V unregulated supply; requires local 22µF/35V ceramic or tantalum bypass capacitor. |
| 3 (SW) | Switch node output | Drives external inductor and Schottky diode (e.g., B340A); carries high di/dt; must be routed short and wide. |
| 4 (FB) | Feedback sensing | Internally tied to 1.23V reference; not user-accessible on fixed-output MIC4681-3.3BM TR variant. |
| 5–8 (GND) | Power and signal ground | All four pins are electrically and thermally common; must connect to large PCB ground plane ≥6 cm² for thermal reliability. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 3.3V output | Eliminates external resistor divider, reducing BOM count and layout sensitivity while ensuring stable 3.3V rail for microcontrollers and logic. |
| Integrated NPN switch | Reduces external component count; supports up to 2A pulsed current ideal for GSM TDMA burst charging profiles. |
| Internal frequency compensation | Enables stable operation with standard 68µH inductor and 220µF output capacitor-no loop compensation design required. |
| Power-SOP-8 thermal design | Pins 5–8 and die paddle form single thermal path; achieves θJC = 20°C/W, enabling 1.4A continuous output without heatsink. |
| 200kHz fixed frequency | Optimizes efficiency vs. EMI trade-off; avoids AM radio band and simplifies EMI filter design compared to variable-frequency controllers. |
Applications
| Cellular Phone Battery Charger | GSM Pulse-Charging Power Supply |
|---|---|
Use Scenario: Charging Li-ion batteries in dual-mode (GSM/TDMA) handsets with pulsed 2A load profiles. IC Role / Device Role / Timing Role: Primary buck regulator providing regulated 3.3V bias and enabling fast transient response during RF transmit bursts. Use Value: Sustains 2A peak current within GSM thermal envelope while maintaining <1.5% output deviation during 100µs load steps. | Use Scenario: Compact, low-component-count power stage for portable communication modules requiring 3.3V/1.4A. IC Role / Device Role / Timing Role: Fixed-output step-down converter replacing discrete MOSFET+controller solutions in space-constrained designs. Use Value: Achieves >85% efficiency at 12V input/3.3V@1A, reducing thermal load versus TO-220-based alternatives. |
| Industrial 24V-to-3.3V Conversion | Embedded System Point-of-Load Regulator |
Use Scenario: Converting 24V factory bus to clean 3.3V for PLC I/O modules or sensor interfaces. IC Role / Device Role / Timing Role: Robust primary DC/DC stage with line/load regulation <±0.5% and 100mVpp ripple at full load. Use Value: Operates continuously across –40°C to +85°C ambient with no derating below 1.2A output due to power-SOP-8 thermal design. | Use Scenario: Local 3.3V supply for FPGA configuration, MCU core, or Ethernet PHY in network edge devices. IC Role / Device Role / Timing Role: High-efficiency, low-noise point-of-load regulator with fast transient recovery (<50µs to 100mV error band). Use Value: Delivers 90% peak efficiency at 6V input, minimizing heat buildup near sensitive analog or RF sections. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678-3.3SD/NOPB | 5A capable, 260kHz, requires external compensation; larger SO-8 package with different pinout. | Higher current, less integrated - suited for designs needing >2A or adjustable output. | Select if scaling beyond 1.4A or requiring programmable soft-start; avoid for drop-in replacement due to pinout mismatch. |
| TPS54331DR | 3A, 570kHz, adjustable output only; requires external feedback resistors and compensation components. | Higher frequency enables smaller magnetics but increases EMI filtering complexity. | Prefer for space-constrained designs where 3.3V can be set via resistors; not suitable for fixed-output simplicity or legacy footprint reuse. |
Compared with LM2678-3.3SD/NOPB and TPS54331DR, the MIC4681-3.3BM TR offers plug-and-play 3.3V regulation with minimal external parts and superior thermal performance in the same SOP-8 footprint-but lacks programmability and higher-current capability.
Availability
MIC4681-3.3BM TR is available at Aetrix Electronics and suitable for cellular phone battery chargers, industrial 24V-to-3.3V conversion, and embedded system point-of-load regulation requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for MIC4681-3.3BM 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 semiconductor company specializing in power management, analog, and timing ICs before its acquisition by Microchip Technology in 2015.
The MIC4681 SuperSwitcher™ product line was engineered for high-efficiency, low-component-count DC/DC conversion in portable and industrial applications-emphasizing thermal robustness, ease of use, and GSM-compliant pulse-current capability.
FAQ
What is the maximum continuous output current of the MIC4681-3.3BM TR at 24V input?
The MIC4681-3.3BM TR delivers up to 1.2A continuous output current at 24V input and 25°C ambient, as confirmed by SOA curves on page 7 of the datasheet. Derating applies above 60°C ambient or with insufficient ground-plane area-minimum 6 cm² recommended for full-rated performance. The MIC4681-3.3BM TR maintains regulation down to 1.0A at 85°C ambient with proper thermal layout.
Does the MIC4681-3.3BM TR require external feedback resistors?
No. The MIC4681-3.3BM TR is a fixed-output variant with internal resistor divider setting 3.3V; the FB pin is not accessible for external adjustment. This differs from the adjustable MIC4681BM, which requires R1/R2. Using the MIC4681-3.3BM TR eliminates feedback component selection errors and improves production consistency.
Can the MIC4681-3.3BM TR be used in a negative-output buck-boost configuration?
Yes-the MIC4681-3.3BM TR supports inverting buck-boost topologies, as documented in Figure 8 of the datasheet (+12V to –12V/150mA). Its internal NPN switch and grounded FB reference allow reconfiguration with external inductor/diode placement. However, output polarity inversion requires careful layout to manage SW node stress and ground return paths.
What is the shutdown threshold voltage for the MIC4681-3.3BM TR?
The MIC4681-3.3BM TR shutdown input (pin 1) asserts disable when SHDN voltage exceeds 1.4V (guaranteed max) and enables regulation when SHDN falls below 0.8V (guaranteed min), with 0.6V typical hysteresis. At VSHDN = 5V, standby current is 6µA; at VSHDN = VIN = 12V, it is 35µA-both values confirmed in Electrical Characteristics tables.
Is the MIC4681-3.3BM TR RoHS-compliant and lead-free?
Yes. The "Y" suffix in MIC4681YM denotes the lead-free version; the "BM" suffix in MIC4681-3.3BM TR indicates the standard (non-lead-free) variant per ordering information on page 2. Both comply with RoHS Directive 2011/65/EU, with lead content <0.1% by weight in homogeneous materials. Full compliance documentation is available upon request.
MIC4681-3.3BM TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- SuperSwitcher™
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- 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):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 1A
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MIC4681-3.3BM TR FAQ
1.How can I place an order for MIC4681-3.3BM TR through Aetrix?
Please submit a Request for Quotation (RFQ) for MIC4681-3.3BM 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 MIC4681-3.3BM TR reliable?
The price and inventory of MIC4681-3.3BM TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MIC4681-3.3BM TR is usually 5 days.
3.What payment methods are accepted for MIC4681-3.3BM TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MIC4681-3.3BM TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MIC4681-3.3BM TR?
MIC4681-3.3BM TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MIC4681-3.3BM 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 MIC4681-3.3BM TR?
For technical support, including MIC4681-3.3BM TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MIC4681-3.3BM TR requirements.
6.How does Aetrix verify that MIC4681-3.3BM TR is sourced from the original manufacturer or authorized distributors?
All MIC4681-3.3BM 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 MIC4681-3.3BM TR meets industry standards.
7.What is the process for return or replacement of MIC4681-3.3BM TR?
All MIC4681-3.3BM TR units undergo pre-shipment inspection (PSI). If there is an issue with MIC4681-3.3BM 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 MIC4681-3.3BM TR part is unused and in its original packaging.
Return procedure for MIC4681-3.3BM TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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