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Analog Devices Inc. LT3684EDD#TRPBF
- Part No.:
- LT3684EDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3684EDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 2A 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,822
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Product details
Overview
LT3684EDD#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic current-mode step-down switching regulator with integrated 0.18Ω NPN switch and boost Schottky diode, supporting 3.6V–34V input, 1.265V–20V adjustable output, 2A continuous load, and 300kHz–2.8MHz programmable frequency. It delivers high efficiency in automotive battery regulation and industrial distributed supplies.
For engineers reviewing the LT3684EDD#TRPBF datasheet, LT3684EDD#TRPBF pinout, LT3684EDD#TRPBF application, or LT3684EDD#TRPBF equivalent, this page provides verified package mapping (10-lead 3mm × 3mm DFN), thermal design guidance (θJC = 10°C/W), soft-start implementation, power-good flag behavior, and validated alternative options for wide-input buck conversion.
Technical Context
The LT3684EDD#TRPBF employs constant-frequency current-mode control with an internal transconductance error amplifier, RS flip-flop oscillator, and active VC-pin clamp for peak-current limiting. Its architecture supports frequency foldback during startup/overload and integrates a bias-regulator that draws power from BIAS pin when ≥3V is present-improving efficiency at high VIN/VOUT ratios.
Operation relies on external RT resistor to set switching frequency (300kHz–2.8MHz), RC network on RUN/SS for soft-start ramp, and feedback divider referenced to 1.265V. The BOOST pin requires external capacitor-diode charge pump to drive the internal bipolar switch fully saturated, enabling low VCESAT (360mV @ 2A) and stable operation up to 34V input.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 34V operating; 36V absolute max - supports automotive cold-crank and industrial unregulated rails. |
| Output Current | 2A continuous - sufficient for powering FPGA I/O banks or microcontroller subsystems without derating. |
| Switching Frequency | 300kHz to 2.8MHz (RT-programmable) - enables compact 4.7µH inductor + ceramic capacitor solutions. |
| Feedback Reference | 1.265V ±10mV - sets precise output voltage via resistor divider; line regulation <0.02%/V ensures stability across input range. |
| Quiescent Current | <1µA in shutdown - preserves battery life in always-on portable or telematics modules. |
| Power Good Flag | Open-collector PG asserts high when VOUT reaches 90% of target - enables safe sequencing in multi-rail systems. |
| Thermal Resistance | θJC = 10°C/W (DFN package) - allows >1.5W dissipation with minimal PCB copper area under typical ambient conditions. |
Pinout & Package
LT3684EDD#TRPBF is housed in a thermally enhanced 10-lead 3mm × 3mm plastic DFN package with exposed pad (Pin 11) soldered to PCB ground for low thermal resistance (θJC = 10°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (Pin 1) | Boost Diode Anode Connection | Connects to Schottky diode anode; forms charge pump node for BOOST pin drive voltage. |
| BOOST (Pin 2) | Switch Driver Supply | Provides >VIN voltage to fully saturate internal NPN switch; rated to 56V max, 30V above SW. |
| SW (Pin 3) | Switch Node | Drives external inductor; connects to catch diode cathode and BOOST capacitor; carries high di/dt pulses. |
| VIN (Pin 4) | Main Input Supply | Supplies internal regulator and switch; must be locally bypassed with ≥4.7µF X7R ceramic capacitor. |
| RUN/SS (Pin 5) | Enable & Soft-Start Control | Logic-high (>2.5V) enables operation; RC network here generates controlled VOUT ramp during startup. |
| PG (Pin 6) | Power Good Output | Open-collector flag pulled high externally; asserts valid only when VIN > 3.5V and RUN/SS is high. |
| BIAS (Pin 7) | Efficiency-Optimized Bias Supply | Accepts ≥3V external source (e.g., VOUT); reduces quiescent loss by shifting bias current path away from VIN. |
| FB (Pin 8) | Feedback Input | Regulated to 1.265V; connects to resistor divider tap; FB bias current ≤100nA minimizes divider error. |
| VC (Pin 9) | Error Amplifier Output | Controls peak switch current; compensation network (RC + CC) tied here sets loop stability and transient response. |
| RT (Pin 10) | Frequency Set Resistor | Grounded resistor sets switching frequency (e.g., 8.66kΩ → 2.8MHz); tolerance directly impacts fSW accuracy. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Boost Schottky Diode | Eliminates external diode, reducing BOM count and board area while maintaining <2µA reverse leakage at 10V. |
| Saturating Switch Design | 0.18Ω on-resistance (VCESAT = 360mV @ 2A) enables high efficiency (>90% at 12V→3.3V/1A) without external MOSFET. |
| Adjustable Soft-Start | Controlled VOUT ramp via RUN/SS RC network prevents inrush current and output overshoot during power-up. |
| Current-Mode Control | Fast transient response and inherent cycle-by-cycle current limiting; no ESR dependency for ceramic output capacitors. |
| Wide Temperature Range | –40°C to +85°C operation (E-grade) - qualified for industrial and automotive under-hood environments. |
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. IC Role / Device Role / Timing Role: Primary buck converter delivering clean, sequenced power with cold-crank support down to 3.6V. Use Value: Integrated boost diode and 34V input rating eliminate need for external protection circuitry; PG flag enables safe boot sequencing. |
Use Scenario: Powering isolated sensor nodes or PLC I/O modules from unregulated 24V DC industrial bus. IC Role / Device Role / Timing Role: High-efficiency point-of-load regulator with adjustable frequency to avoid noise-sensitive bands (e.g., 1.25MHz). Use Value: 2.8MHz max switching enables tiny 2.2µH inductors and 10µF ceramic output caps - minimizing footprint in space-constrained enclosures. |
| Portable Product Power | Wall Transformer Regulation |
|
Use Scenario: Converting 5V–19V USB PD or wall adapter output to 1.2V core voltage for ARM Cortex-M7 SoC. IC Role / Device Role / Timing Role: Adjustable-output buck regulator with BIAS pin optimization to maintain >88% efficiency across 5V–19V input range. Use Value: BIAS pin connection to VOUT reduces quiescent current draw from input rail - extending battery runtime in standby mode. |
Use Scenario: Replacing linear regulators in AC/DC adapter secondary side to improve efficiency and reduce thermal stress. IC Role / Device Role / Timing Role: Wide-input buck controller accepting rectified 9V–36V DC from transformer secondary. Use Value: 36V absolute max rating accommodates 30V transients common in low-cost transformer designs; soft-start prevents fuse blow during plug-in. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EMSE#TRPBF | 42V input, 3.5A, synchronous rectification, 200kHz–3MHz, no integrated boost diode | Higher current, lower IQ (2.5µA), but requires external high-side MOSFET and bootstrap capacitor | Choose for higher efficiency at light loads or when synchronous operation is mandatory; not drop-in due to different pinout and control scheme. |
| TPS54202DDCR | 28V input, 2A, integrated FETs, 400kHz–2.5MHz, 1.5µA shutdown IQ, no BIAS pin | Lacks BIAS pin optimization and integrated boost diode; uses external bootstrap capacitor instead | Prefer for cost-sensitive consumer applications where 28V max input suffices; requires redesign of biasing and boost circuitry. |
Compared with LT3684EDD#TRPBF, LT8610EMSE#TRPBF offers higher current and lower quiescent current but demands external components and layout changes, while TPS54202DDCR simplifies BOM with synchronous FETs yet sacrifices BIAS-driven efficiency gains and boost integration critical for high-VIN operation.
Availability
LT3684EDD#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 assurance, and traceable sourcing.
Supply support for LT3684EDD#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 ICs, serving precision instrumentation, industrial automation, and automotive markets.
The LT3684EDD#TRPBF belongs to Linear's high-voltage monolithic buck regulator family, designed specifically for robust, compact DC/DC conversion in harsh environments where wide input range, thermal resilience, and integrated functionality are essential.
FAQ
What is the maximum input voltage rating for LT3684EDD#TRPBF?
The LT3684EDD#TRPBF has an absolute maximum VIN rating of 36V, with continuous operation supported up to 34V. During normal regulation, 36V transients are acceptable; however, during startup or short-circuit events, VIN must remain below 34V or satisfy the equation VIN(MAX) = (VOUT + VD)/(1 − fSW·tON(MIN)) − VD + VSW to prevent unsafe duty cycle limits.
Does LT3684EDD#TRPBF require an external catch diode?
No, the LT3684EDD#TRPBF integrates a boost Schottky diode connected to the BD pin, eliminating the need for an external catch diode. This reduces component count and PCB area while maintaining low reverse leakage (<2µA at 10V) and enabling full switch saturation via the BOOST pin charge pump.
How is soft-start implemented on LT3684EDD#TRPBF?
Soft-start on LT3684EDD#TRPBF is implemented via an RC network connected between RUN/SS and ground. Charging this capacitor ramps the RUN/SS voltage, which internally clamps the VC pin voltage - resulting in a controlled rise of output voltage without inrush current or overshoot. Typical values are 16.2kΩ and 330pF for ~1ms ramp time.
What is the purpose of the BIAS pin on LT3684EDD#TRPBF?
The BIAS pin on LT3684EDD#TRPBF accepts an external ≥3V supply (typically VOUT) to power the internal regulator, diverting bias current away from VIN. This improves conversion efficiency-especially when VIN significantly exceeds VOUT-by reducing quiescent losses in the input path and lowering overall system power dissipation.
Can LT3684EDD#TRPBF operate in discontinuous conduction mode (DCM)?
Yes, the LT3684EDD#TRPBF supports discontinuous conduction mode, particularly at light loads or with higher inductance values. Its current-mode architecture maintains stability in DCM, though maximum output current decreases compared to continuous mode due to reduced energy transfer per cycle and increased peak inductor current requirements.
LT3684EDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN 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-DFN (3x3)
LT3684EDD#TRPBF FAQ
1.How can I place an order for LT3684EDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3684EDD#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 LT3684EDD#TRPBF reliable?
The price and inventory of LT3684EDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3684EDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3684EDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3684EDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3684EDD#TRPBF?
LT3684EDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3684EDD#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 LT3684EDD#TRPBF?
For technical support, including LT3684EDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3684EDD#TRPBF requirements.
6.How does Aetrix verify that LT3684EDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3684EDD#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 LT3684EDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3684EDD#TRPBF?
All LT3684EDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3684EDD#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 LT3684EDD#TRPBF part is unused and in its original packaging.
Return procedure for LT3684EDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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