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Analog Devices Inc. LT3684IMSE#PBF
- Part No.:
- LT3684IMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3684IMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 2A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,309
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Product details
Overview
LT3684IMSE#PBF from Analog Devices (formerly Linear Technology) is a 36V, 2A, adjustable-frequency (300kHz–2.8MHz) monolithic buck switching regulator with integrated 0.18Ω NPN switch and boost Schottky diode. It operates from 3.6V to 34V input, delivers 1.265V–20V adjustable output, and features power good flag, soft-start, and current-mode control for fast transient response - used in automotive battery regulation and industrial distributed supplies.
For engineers reviewing the LT3684IMSE#PBF datasheet, LT3684IMSE#PBF pinout, LT3684IMSE#PBF application, or LT3684IMSE#PBF equivalent, key selection considerations include its 10-pin MSOP package with exposed pad, 1.265V feedback reference, <1µA shutdown current, integrated boost diode, and thermal performance validated over –40°C to 125°C.
Technical Context
The LT3684IMSE#PBF implements constant-frequency current-mode PWM control using an internal oscillator set by the RT pin resistor, enabling precise frequency tuning from 300kHz to 2.8MHz. Its bipolar NPN switch is driven via an external BOOST capacitor/diode network to ensure full saturation at high input voltages.
Operation relies on real-time peak current sensing between VIN and SW pins, error amplifier servoing of the VC pin to regulate FB at 1.265V, and active VC clamping for current limiting. The BIAS pin enables efficiency optimization by sourcing bias current from VOUT when >3V, reducing VIN supply burden.
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 FPGA I/O banks, microcontroller cores, or sensor subsystems. |
| Switching Frequency | Adjustable 300kHz–2.8MHz via RT pin resistor - enables tradeoff between small magnetics (high f) and efficiency/minimum dropout (low f). |
| Feedback Reference | 1.265V ±15mV - sets output voltage accuracy and stability across temperature; used with external resistor divider. |
| Shutdown Current | <1µA - enables ultra-low-power system sleep modes without compromising startup reliability. |
| Power Good Flag | Open-collector PG asserts high when VOUT reaches 90% of regulation - provides deterministic sequencing signal for downstream logic. |
| Thermal Rating | –40°C to +125°C junction - qualified for under-hood automotive and high-ambient industrial environments. |
Pinout & Package
LT3684IMSE#PBF is housed in a thermally enhanced 10-lead plastic MSOP package with exposed pad (Pin 11), requiring PCB soldering for optimal thermal resistance (θJC = 10°C/W). The exposed pad is electrically GND.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (1) | Boost diode anode connection | Connects to Schottky diode anode; completes bootstrap charge path for BOOST pin drive. |
| BOOST (2) | Bootstrap voltage supply | Provides >VIN voltage to fully saturate internal NPN switch; requires external capacitor and diode. |
| SW (3) | Switch node | Drives external inductor; carries high di/dt switching current - must be routed with minimal loop area. |
| VIN (4) | Main input supply | Supplies power to internal regulator and switch; requires local 4.7µF ceramic bypass near pin. |
| RUN/SS (5) | Enable & soft-start control | Pull ≥2.5V to enable; apply RC ramp for controlled VOUT rise; pull ≤0.2V to enter <1µA shutdown. |
| PG (6) | Power good open-collector output | Sinks current until FB reaches 90% of 1.265V; requires external pull-up for logic-level signaling. |
| BIAS (7) | Efficiency-optimized bias supply | Accepts external ≥3V source (e.g., VOUT) to reduce VIN current draw and improve efficiency at high VIN/VOUT ratios. |
| FB (8) | Feedback input | Regulated to 1.265V; connects to resistor divider tap - determines output voltage with ±1.2% typical accuracy. |
| VC (9) | Error amplifier output | Controls peak switch current; compensation network (RC + CC) connected here stabilizes current-mode loop. |
| RT (10) | Oscillator frequency setting | Resistor to GND sets switching frequency per published table (e.g., 8.66kΩ = 2.8MHz). |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost Schottky diode | Eliminates external diode, reduces BOM count and board space while maintaining efficient bootstrap operation. |
| Current-mode control architecture | Enables inherent cycle-by-cycle current limiting and stable operation with ceramic output capacitors (no ESR required). |
| Adjustable soft-start via RUN/SS pin | Prevents inrush current and output overshoot during power-up using simple external R-C network. |
| Thermally enhanced MSOP package | 10-lead MSOP with exposed pad achieves θJA = 45°C/W - enables 2A operation without forced air in compact layouts. |
| Wide-input, high-efficiency bias architecture | BIAS pin allows >3V auxiliary supply (e.g., VOUT) to power internal circuitry, improving efficiency by up to 3% at VIN = 24V, VOUT = 3.3V. |
Applications
| Automotive Battery Regulation | Industrial Distributed Supply |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery rail to 3.3V or 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 isolated, regulated low-voltage domain with robust input transient handling. Use Value: Withstands 36V transients and operates down to 3.6V, eliminating need for external TVS or pre-regulator stages in ASIL-B systems. |
Use Scenario: Powering remote I/O modules in factory automation systems where 24V DC distribution bus feeds multiple point-of-load regulators. IC Role / Device Role / Timing Role: Local DC-DC conversion stage delivering stable 5V/12V to PLC analog front-ends and digital isolators. Use Value: 2A capability and –40°C to 125°C rating support uncooled DIN-rail mounted enclosures; adjustable frequency avoids noise-sensitive bands. |
| Portable Product Power | Wall Transformer Regulation |
Use Scenario: Converting 9–30V wide-input wall adapter output to 1.8V/3.3V for handheld medical devices with strict battery-life requirements. IC Role / Device Role / Timing Role: High-efficiency step-down regulator minimizing quiescent loss during standby and active modes. Use Value: <1µA shutdown current extends shelf life; BIAS pin operation from VOUT improves light-load efficiency by 15–20% vs. VIN-only biasing. |
Use Scenario: Replacing linear regulators in legacy AC/DC adapters to achieve higher efficiency and lower thermal dissipation in compact enclosures. IC Role / Device Role / Timing Role: Primary switching regulator replacing 78xx series, accepting rectified/unfiltered DC input up to 34V. Use Value: Integrated switch and boost diode reduce component count by 4 parts; 2.8MHz option enables <2mm height designs with 1µH inductors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3630EMSE#PBF | 40V input, 1.5A, integrated MOSFETs (no external diode needed), but no BOOST pin or BIAS pin optimization. | Better suited for low-noise, low-EMI applications due to spread-spectrum option; lacks automotive temp grade. | Select if needing MOSFET-based simplicity and EMI reduction over wide-VIN headroom and thermal robustness. |
| TPS54240DGQR | 40V input, 2.5A, external MOSFET driver, no integrated diode or BOOST circuit; requires external bootstrap components. | Higher current and wider VIN, but larger solution size and more complex layout; rated only to 105°C. | Select if maximum output current >2A is required and board space allows discrete FET + gate driver implementation. |
Compared with LTC3630EMSE#PBF and TPS54240DGQR, the LT3684IMSE#PBF uniquely combines bipolar switch saturation via BOOST, BIAS-driven efficiency gain, and full –40°C to 125°C qualification - making it optimal for space-constrained, thermally demanding automotive and industrial buck applications where integration and ruggedness outweigh raw current or EMI specs.
Availability
LT3684IMSE#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial distributed supply, and portable product power applications requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3684IMSE#PBF 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 ICs, serving precision instrumentation, industrial, automotive, and communications markets.
The LT3684IMSE#PBF belongs to Linear's monolithic buck regulator product line, designed specifically for wide-input, high-reliability DC-DC conversion in harsh environments - emphasizing thermal resilience, transient robustness, and minimal external component count.
FAQ
What is the maximum input voltage rating for LT3684IMSE#PBF?
The LT3684IMSE#PBF has an absolute maximum VIN rating of 36V, with continuous operation specified up to 34V. During normal regulation, 36V transients are acceptable; however, during startup or short-circuit conditions, VIN must remain below 34V or be limited by the frequency-dependent equation VIN(MAX) = (VOUT + VD)/(1 − fSW·tON(MIN)) − VD + VSW. This ensures safe switch operation given its ~150ns minimum on-time.
Does LT3684IMSE#PBF require an external catch diode?
No, the LT3684IMSE#PBF integrates a boost Schottky diode and does not require an external catch diode. The BD pin connects directly to the anode of the internal diode, and the BOOST pin supplies the elevated gate drive voltage needed for the internal bipolar NPN switch. An external Schottky diode is only required for the BOOST capacitor charging path - not for output rectification.
How is output voltage programmed on LT3684IMSE#PBF?
The LT3684IMSE#PBF uses a resistor divider from VOUT to GND, with the FB pin connected to the divider midpoint. Output voltage is set by VOUT = 1.265V × (1 + R1/R2), where R1 is the top resistor (VOUT to FB) and R2 is the bottom resistor (FB to GND). The 1.265V reference has ±1.2% typical tolerance over temperature, and FB pin bias current is only 30–100nA, minimizing divider error.
What is the purpose of the BIAS pin on LT3684IMSE#PBF?
The BIAS pin on LT3684IMSE#PBF accepts an external ≥3V supply (typically VOUT) to power the internal regulator, reducing current drawn from VIN. This improves efficiency - especially at high VIN/VOUT ratios - by up to 3% at VIN = 24V, VOUT = 3.3V. When left unconnected, the device defaults to VIN biasing, which increases quiescent current and reduces light-load efficiency.
Can LT3684IMSE#PBF operate in discontinuous conduction mode (DCM)?
Yes, the LT3684IMSE#PBF can operate in discontinuous conduction mode (DCM) at light loads or with high switching frequencies and small inductors. Its current-mode architecture remains stable in DCM, and the datasheet confirms valid operation down to ~100mA load. However, maximum output current is reduced in DCM, and output ripple increases - design guidelines recommend sizing inductors to maintain CCM above 20% of full load for optimal performance.
LT3684IMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- 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#PBF FAQ
1.How can I place an order for LT3684IMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3684IMSE#PBF 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#PBF reliable?
The price and inventory of LT3684IMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3684IMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3684IMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3684IMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3684IMSE#PBF?
LT3684IMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3684IMSE#PBF 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#PBF?
For technical support, including LT3684IMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3684IMSE#PBF requirements.
6.How does Aetrix verify that LT3684IMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3684IMSE#PBF 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#PBF meets industry standards.
7.What is the process for return or replacement of LT3684IMSE#PBF?
All LT3684IMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3684IMSE#PBF, 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#PBF part is unused and in its original packaging.
Return procedure for LT3684IMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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