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Analog Devices Inc. LT3684IMSE#TRPBF
- Part No.:
- LT3684IMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3684IMSE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 2A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,989
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Product details
Overview
LT3684IMSE#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic current-mode step-down switching regulator with 3.6V–34V input range, 2A output capability, and adjustable 300kHz–2.8MHz switching frequency. It integrates a 0.18Ω bipolar NPN switch, boost Schottky diode, soft-start control, power-good flag, and 1.265V feedback reference-designed for automotive battery regulation, industrial supplies, and wall transformer-derived power rails.
For engineers reviewing the LT3684IMSE#TRPBF datasheet, LT3684IMSE#TRPBF pinout, LT3684IMSE#TRPBF application, or LT3684IMSE#TRPBF equivalent, key selection criteria include its thermally enhanced 10-pin MSOP package with exposed pad, integrated boost diode eliminating external components, 1µA shutdown current, and guaranteed operation up to 125°C junction temperature in industrial and automotive environments.
Technical Context
The LT3684IMSE#TRPBF employs constant-frequency current-mode control with an internal oscillator set by an external RT resistor, enabling precise duty-cycle management and fast transient response. Its error amplifier servo-controls the VC pin to regulate peak switch current, while active clamping on VC provides overcurrent protection and soft-start ramping via the RUN/SS pin.
Power delivery architecture uses BIAS pin sourcing to improve efficiency at high VIN/VOUT ratios, and BOOST-SW charge-pump topology ensures full saturation of the internal bipolar switch. Frequency foldback during startup or overload prevents current runaway, and the PG comparator asserts when FB reaches 90% of 1.265V-valid only when VIN > 3.6V and RUN/SS is high.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 34V operating; 36V absolute max - supports wide-range industrial and automotive inputs including cold-crank and load-dump conditions. |
| Output Current | Up to 2A continuous - limited by thermal design and inductor saturation; switch current limit ranges 2.5A–3.6A depending on duty cycle. |
| Switching Frequency | 300kHz to 2.8MHz (RT-programmable) - enables compact magnetics and ceramic capacitors while balancing efficiency vs. EMI. |
| Feedback Reference | 1.265V ±10mV over temperature - sets output voltage accuracy and stability across –40°C to 125°C operating range. |
| Shutdown Current | <1µA - enables ultra-low-power standby in battery-backed systems without external enable circuitry. |
| Thermal Rating | 125°C max junction temperature (I-grade) - validated for industrial and extended-temperature applications with θJC = 10°C/W. |
| Package | 10-pin MSOP with exposed pad - low thermal resistance (θJA = 45°C/W) requires PCB soldering of exposed pad to GND plane. |
Pinout & Package
LT3684IMSE#TRPBF is housed in a 10-lead plastic MSOP package with exposed thermal pad (Pin 11), requiring soldering to PCB ground for thermal and electrical integrity. Pin pitch is 0.5mm; body dimensions are 3mm × 3mm × 1.1mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (Pin 1) | Boost Diode Anode Connection | Connects to anode of external Schottky diode used in boost capacitor charging path; must be routed with low-inductance trace. |
| BOOST (Pin 2) | Charge-Pump Drive Node | Provides elevated gate drive voltage (>VIN) to fully saturate internal bipolar switch; requires external boost capacitor between BOOST and SW. |
| SW (Pin 3) | Switch Node | High-current output of internal power switch; connects directly to inductor, catch diode cathode, and boost capacitor. |
| VIN (Pin 4) | Main Input Supply | Supplies current to internal regulator and switch; requires local 4.7µF ceramic bypass capacitor placed adjacent to pin. |
| RUN/SS (Pin 5) | Enable & Soft-Start Control | Pull ≥2.5V to enable; tie to GND for shutdown (<1µA IQ); RC network here controls output voltage ramp rate during startup. |
| PG (Pin 6) | Power-Good Open-Drain Flag | Sinks current when VOUT < 90% of regulation; requires external pull-up; valid only if VIN > 3.6V and RUN/SS high. |
| BIAS (Pin 7) | Efficiency-Optimized Bias Supply | Accepts external voltage ≥3V (typically VOUT); reduces quiescent current and improves efficiency at high VIN/VOUT ratios. |
| FB (Pin 8) | Feedback Input | Regulated to 1.265V; connects to resistor divider tap; determines output voltage via R1/R2 ratio per datasheet equation. |
| VC (Pin 9) | Error Amplifier Output | Controls peak switch current; compensation network (RC + CC) connected here stabilizes control loop and manages transients. |
| RT (Pin 10) | Frequency Set Resistor | Resistor to GND programs switching frequency from 300kHz to 2.8MHz; values range 8.66kΩ (2.8MHz) to 267kΩ (300kHz). |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Boost Schottky Diode | Eliminates need for external boost diode, reducing BOM count and layout area while maintaining reliable charge-pump operation. |
| Thermally Enhanced MSOP Package | Exposed pad lowers thermal resistance (θJC = 10°C/W), enabling 2A operation at 125°C ambient with proper PCB copper area. |
| Programmable Switching Frequency | RT-resistor tuning allows optimization of inductor size, efficiency, and EMI profile across diverse input/output combinations. |
| Power-Good Flag with Hysteresis | PG asserts open-drain output when FB reaches 90% of 1.265V (±10mV hysteresis), providing reliable system power sequencing signal. |
| BIAS Pin Efficiency Architecture | Draws bias current from regulated output instead of VIN when BIAS ≥3V, improving full-load efficiency by up to 3% at high VIN/VOUT ratios. |
Applications
| Automotive Battery Regulation | Industrial Distributed Power |
|---|---|
|
Use Scenario: Regulating 12V or 24V vehicle battery supply to 3.3V/5V for infotainment ECUs under cold-crank (4.5V) and load-dump (36V) conditions. IC Role / Device Role / Timing Role: Primary buck converter delivering stable 2A output with built-in overvoltage and thermal protection. Use Value: Eliminates need for external surge protection and discrete boost diode; operates continuously across –40°C to 125°C without derating. |
Use Scenario: Point-of-load conversion in programmable logic controllers (PLCs) where 24V field bus powers 5V I/O modules and 3.3V microcontrollers. IC Role / Device Role / Timing Role: High-efficiency, thermally robust DC-DC stage supporting long-term reliability in enclosed industrial enclosures. Use Value: Exposed-pad MSOP package enables conduction cooling; 1µA shutdown supports low-power sleep modes during communication idle periods. |
| Wall Transformer Regulation | Portable Product Power |
|
Use Scenario: Converting unregulated 9–36V AC/DC adapter output to clean 5V for USB peripherals or IoT gateways with variable load profiles. IC Role / Device Role / Timing Role: Primary regulator handling wide-input ripple and line transients; includes soft-start to prevent inrush into downstream capacitance. Use Value: Adjustable frequency avoids audible noise in sensitive audio applications; integrated PG flag enables safe firmware boot sequencing. |
Use Scenario: Powering handheld medical devices or ruggedized tablets using Li-ion battery (3.0–4.2V) or universal input (5–24V) sources. IC Role / Device Role / Timing Role: High-efficiency buck stage delivering 2A at 3.3V with minimal solution footprint and low quiescent current in standby. Use Value: BIAS pin operation from VOUT extends battery runtime; 300kHz minimum frequency supports use of low-DCR, low-profile inductors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8609SIV#TRPBF | 42V input, 2.5A, 2MHz sync rectification, 2.5µA IQ; requires external bootstrap diode; no integrated boost diode. | Better efficiency at light loads; lacks integrated boost diode and BIAS pin optimization for high VIN/VOUT. | Choose LT8609S for ultra-low IQ and synchronous rectification where board space permits external diode and layout complexity is acceptable. |
| MP2451DT-LF-Z | 36V input, 0.6A, 2MHz, no BIAS pin, no PG flag, no soft-start control; smaller SOIC-8 package. | Limited output current and missing diagnostics; suitable only for lower-power, cost-sensitive designs without sequencing requirements. | Choose MP2451 for sub-1A applications where PG, soft-start, and thermal performance are non-critical and BOM cost is primary constraint. |
Compared with LT3684IMSE#TRPBF, LT8609SIV#TRPBF offers higher integration of synchronous rectification but requires external boost components, while MP2451DT-LF-Z sacrifices current capability, diagnostics, and thermal robustness to reduce footprint and cost-making LT3684IMSE#TRPBF optimal for 2A industrial/automotive buck applications demanding reliability, diagnostics, and wide-temperature operation.
Availability
LT3684IMSE#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial distributed power, and wall transformer-derived supplies requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3684IMSE#TRPBF 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
Analog Devices (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3684 product line delivers rugged, wide-input buck regulators optimized for harsh environments-including automotive, industrial control, and telecom infrastructure-where reliability, thermal performance, and integrated protection features are critical.
FAQ
What is the maximum operating temperature for the LT3684IMSE#TRPBF?
The LT3684IMSE#TRPBF is rated for operation from –40°C to +125°C junction temperature. Its I-grade specification guarantees full electrical performance across this range, and the thermally enhanced MSOP package with exposed pad enables sustained 2A output at elevated ambient temperatures when properly mounted to a thermal plane.
Does the LT3684IMSE#TRPBF require an external boost diode?
No-the LT3684IMSE#TRPBF integrates a boost Schottky diode internally. Pin BD (Pin 1) connects to the anode of this internal diode, and the BOOST pin (Pin 2) forms the charge-pump node with the external boost capacitor. No external boost diode is needed, simplifying layout and reducing BOM count.
How is the switching frequency set on the LT3684IMSE#TRPBF?
The switching frequency of the LT3684IMSE#TRPBF is set by connecting a single resistor from the RT pin (Pin 10) to ground. Values range from 8.66kΩ for 2.8MHz down to 267kΩ for 300kHz. The relationship is monotonic and documented in the datasheet's Figure 1, enabling precise frequency selection without trimming or calibration.
Can the LT3684IMSE#TRPBF operate with input voltage above 34V?
Yes-transient input voltages up to 36V are permitted when the output is in regulation and no startup or short-circuit events occur. During startup or fault conditions, VIN must remain ≤34V. This dual-rating supports automotive load-dump immunity while maintaining safe operation during normal regulation.
What is the purpose of the BIAS pin on the LT3684IMSE#TRPBF?
The BIAS pin (Pin 7) accepts an external voltage ≥3V-typically the regulated output-to power the internal control circuitry. This reduces quiescent current drawn from VIN and improves full-load efficiency by up to 3% in high VIN/VOUT applications, such as converting 24V to 3.3V, where traditional biasing from VIN would waste significant power.
LT3684IMSE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.6V
- Voltage - Input (Max):
- 34V
- Voltage - Output (Min/Fixed):
- 1.265V
- Voltage - Output (Max):
- 20V
- Current - Output:
- 2A
- Frequency - Switching:
- 300kHz ~ 3MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LT3684IMSE#TRPBF FAQ
1.How can I place an order for LT3684IMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3684IMSE#TRPBF 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 LT3684IMSE#TRPBF reliable?
The price and inventory of LT3684IMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3684IMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3684IMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3684IMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3684IMSE#TRPBF?
LT3684IMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3684IMSE#TRPBF 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 LT3684IMSE#TRPBF?
For technical support, including LT3684IMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3684IMSE#TRPBF requirements.
6.How does Aetrix verify that LT3684IMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3684IMSE#TRPBF 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 LT3684IMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3684IMSE#TRPBF?
All LT3684IMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3684IMSE#TRPBF, 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 LT3684IMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3684IMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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