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Analog Devices Inc. LT3684EMSE#TRPBF
- Part No.:
- LT3684EMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3684EMSE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 2A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,089
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Product details
Overview
LT3684EMSE#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 300kHz–2.8MHz current-mode step-down switching regulator with integrated 0.18Ω NPN switch and boost Schottky diode, supporting 3.6V–34V input and delivering up to 2A at adjustable output voltages from 1.265V to 20V. It features power good flag, soft-start, and thermal enhancement via exposed pad in 10-pin MSOP package - used in automotive battery regulation and industrial distributed supplies.
For engineers reviewing the LT3684EMSE#TRPBF datasheet, LT3684EMSE#TRPBF pinout, LT3684EMSE#TRPBF application, or LT3684EMSE#TRPBF equivalent, key selection considerations include its 2A output capability, 300kHz–2.8MHz programmable frequency, 1.265V feedback reference, integrated boost diode, and −40°C to +85°C operating range in thermally enhanced MSOP.
Technical Context
The LT3684EMSE#TRPBF employs constant-frequency current-mode control with an internal transconductance error amplifier driving the VC pin to regulate peak switch current. Its oscillator frequency is set by an external resistor on the RT pin, enabling precise tradeoffs between inductor size, efficiency, and input voltage range.
Operation relies on bipolar NPN switch saturation driven by BOOST pin voltage (≥VIN + 1.6V), with BIAS pin allowing external biasing from VOUT to improve efficiency at high VIN/VOUT ratios. Power good (PG) asserts when FB reaches 90% of 1.265V, and shutdown draws <1µA via RUN/SS pin.
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 without external pre-regulation. |
| Output Current | Up to 2A continuous - sufficient for powering microcontrollers, FPGAs, and analog subsystems in compact designs. |
| Switching Frequency | 300kHz to 2.8MHz (RT-programmable) - enables use of sub-5mm inductors and ceramic capacitors while balancing efficiency vs. size. |
| Feedback Reference | 1.265V ±10mV - sets output voltage accuracy and stability across temperature; used with external resistor divider. |
| Quiescent Current | <1µA in shutdown - preserves battery life in always-on portable or remote sensing applications. |
| On-Resistance | 0.18Ω typical - minimizes conduction loss at full load, supporting >90% efficiency at 12V→3.3V/2A. |
| Thermal Package | 10-pin MSOP with exposed pad - θJC = 10°C/W enables high-power operation without heatsink in space-constrained layouts. |
Pinout & Package
LT3684EMSE#TRPBF is housed in a 10-lead plastic MSOP package with exposed pad (Pin 11) soldered to PCB for thermal and electrical grounding. Pin pitch is 0.5mm; body dimensions are standard MSOP (3mm × 3mm footprint).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (1) | Boost diode anode connection | Connects external Schottky anode to enable BOOST voltage generation; critical for NPN switch saturation. |
| BOOST (2) | High-side gate drive supply | Must be ≥VIN + 1.6V to fully saturate internal NPN switch; sourced via external capacitor/diode from SW node. |
| SW (3) | Switch node | Drives inductor and catch diode; carries high di/dt pulses - requires tight layout and low-inductance routing. |
| VIN (4) | Main input supply | Supplies internal regulator and switch; must be locally bypassed with ≥4.7µF X7R ceramic capacitor. |
| RUN/SS (5) | Enable & soft-start control | Pull ≥2.5V to enable; apply RC ramp to implement controlled VOUT rise time and reduce inrush stress. |
| PG (6) | Power good open-collector flag | Sinks current when FB < 90% of 1.265V; requires external pull-up to indicate valid regulation. |
| BIAS (7) | Efficiency-optimized bias supply | Accepts external ≥3V source (e.g., VOUT) to reduce VIN current draw and improve light-load efficiency. |
| FB (8) | Feedback input | Regulated to 1.265V; connects to resistor divider tap - determines output voltage with ±1% typical accuracy. |
| VC (9) | Error amplifier output | Controls peak switch current; compensation network (RC + CC) connected here sets loop stability and transient response. |
| RT (10) | Oscillator frequency set | Resistor to ground programs switching frequency from 300kHz to 2.8MHz per datasheet table. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost Schottky diode | Eliminates external diode, reducing BOM count and PCB area while ensuring reliable BOOST voltage generation. |
| Programmable switching frequency | Enables optimization of magnetic component size, EMI profile, and efficiency across diverse input/output conditions. |
| Power good (PG) flag | Provides system-level sequencing and fault detection by signaling when regulated output reaches 90% of target. |
| Soft-start via RUN/SS pin | Prevents inrush current and output overshoot using externally adjustable RC time constant - no additional IC required. |
| BIAS pin for efficiency boost | Allows sourcing control circuitry bias from VOUT instead of VIN, improving efficiency by up to 3% at high input voltages. |
Applications
| Automotive Battery Regulation | Industrial Distributed Supply |
|---|---|
Use Scenario: Regulating 12V or 24V vehicle battery rail to 3.3V/5V for infotainment MCU and CAN transceivers under cold-crank (6V) and load-dump (36V) conditions. IC Role / Device Role / Timing Role: Primary buck converter providing stable, ripple-controlled power with PG monitoring for safe boot sequence. Use Value: Withstands 36V transients and operates down to 3.6V input, eliminating need for upstream TVS or LDO pre-regulator in cost-sensitive modules. | Use Scenario: Local point-of-load conversion in PLC backplanes or sensor nodes where 24V field bus powers multiple 5V/3.3V subsystems. IC Role / Device Role / Timing Role: High-efficiency DC-DC stage delivering 2A with minimal thermal rise in confined enclosures. Use Value: Exposed-pad MSOP package achieves θJA = 45°C/W, enabling 2A operation without heatsink at 60°C ambient. |
| Portable Product Power | Wall Transformer Regulation |
Use Scenario: Converting 9–24V wall adapter or Li+ battery pack output to 1.8V/3.3V for wireless SoCs and display drivers in handheld test equipment. IC Role / Device Role / Timing Role: Compact, high-frequency buck regulator enabling small inductor/capacitor solution with soft-start for clean power-up. Use Value: 2.8MHz operation allows 1µH inductor and 10µF total output capacitance - reduces solution volume by >40% vs. 500kHz alternatives. | Use Scenario: Replacing linear regulators in legacy AC/DC adapters to improve efficiency and reduce heat in enclosed power supplies. IC Role / Device Role / Timing Role: Efficient step-down stage converting unregulated rectified DC (e.g., 30V) to stable 5V/12V outputs. Use Value: Integrated switch and boost diode eliminate two discrete components; 0.18Ω RDS(on) sustains >88% efficiency at full load even with 30V input. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3630EMSE#TRPBF | Higher 3.5A rating, 3MHz max frequency, but requires external MOSFET and bootstrap capacitor; no integrated boost diode. | Better suited for >2A loads or ultra-high-frequency designs requiring external FET control. | Select LTC3630EMSE#TRPBF only if higher current or synchronous rectification is required - adds complexity and BOM cost. |
| MP2451DT-LF-Z | 2A, 2MHz max, integrated MOSFET but no boost diode; 4.5–36V input; 0.8V ref; smaller 8-pin SOIC package. | Lacks BIAS pin and PG flag; lower thermal performance (no exposed pad); limited to ≤85°C ambient. | Choose MP2451DT-LF-Z for cost-sensitive, non-automotive applications where PG monitoring and extended thermal margin are not required. |
Compared with LTC3630EMSE#TRPBF and MP2451DT-LF-Z, LT3684EMSE#TRPBF uniquely combines integrated boost diode, BIAS pin for efficiency optimization, power good flag, and exposed-pad MSOP thermal performance - making it optimal for automotive and industrial applications demanding reliability, simplicity, and thermal headroom.
Availability
LT3684EMSE#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial distributed supply, and portable product power applications requiring stable component supply, long-term lifecycle support, and guaranteed −40°C to +85°C operation.
Supply support for LT3684EMSE#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 and maintains its high-performance power management portfolio with rigorous qualification and long-term support.
The LT3684 series was designed for rugged, wide-input DC-DC conversion in automotive, industrial, and telecom infrastructure - emphasizing thermal robustness, transient immunity, and integration of critical support functions.
FAQ
What is the maximum input voltage rating for LT3684EMSE#TRPBF during normal regulation?
The LT3684EMSE#TRPBF supports up to 36V input voltage during normal regulation mode, including transient conditions like load dump. In startup or short-circuit modes, the maximum safe input is 34V. This rating is confirmed in the Absolute Maximum Ratings table and applies specifically to the LT3684EMSE#TRPBF variant with −40°C to +85°C temperature grade.
Does LT3684EMSE#TRPBF require an external catch diode?
No, LT3684EMSE#TRPBF does not require an external catch diode because it integrates a boost Schottky diode connected to the BD pin. However, an external Schottky diode is still required between SW and ground (or output) to serve as the catch diode - the integrated diode only supports BOOST capacitor charging. This configuration is shown in all official LT3684EMSE#TRPBF application schematics.
How is the output voltage programmed on LT3684EMSE#TRPBF?
The output voltage of LT3684EMSE#TRPBF is programmed using a resistor divider between VOUT and the FB pin, referenced to the internal 1.265V feedback voltage. The formula is R1 = R2 × ((VOUT / 1.265) − 1), where R2 connects FB to ground. This method is specified in the Applications Information section and validated across the full −40°C to +85°C operating range of LT3684EMSE#TRPBF.
What is the purpose of the BIAS pin on LT3684EMSE#TRPBF?
The BIAS pin on LT3684EMSE#TRPBF allows the IC to draw bias current from an external voltage source (e.g., VOUT) instead of VIN, improving efficiency - especially when VIN is significantly higher than VOUT. When BIAS ≥3V, internal regulator current shifts from VIN to BIAS, reducing total input current and thermal load. This behavior is documented in the Operation section and Electrical Characteristics table for LT3684EMSE#TRPBF.
Can LT3684EMSE#TRPBF operate in pulse-skipping mode?
Yes, LT3684EMSE#TRPBF enters pulse-skipping mode during light loads or when input voltage exceeds the duty-cycle limit for continuous conduction - maintaining regulation while reducing switching losses. This behavior is explicitly described in the Applications Information section and confirmed in Typical Performance Characteristics plots (e.g., G04, G05). Pulse skipping occurs automatically and does not require external configuration on LT3684EMSE#TRPBF.
LT3684EMSE#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 ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LT3684EMSE#TRPBF FAQ
1.How can I place an order for LT3684EMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3684EMSE#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 LT3684EMSE#TRPBF reliable?
The price and inventory of LT3684EMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3684EMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3684EMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3684EMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3684EMSE#TRPBF?
LT3684EMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3684EMSE#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 LT3684EMSE#TRPBF?
For technical support, including LT3684EMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3684EMSE#TRPBF requirements.
6.How does Aetrix verify that LT3684EMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3684EMSE#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 LT3684EMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3684EMSE#TRPBF?
All LT3684EMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3684EMSE#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 LT3684EMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3684EMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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