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Analog Devices Inc. LT3680IDD#TRPBF
- Part No.:
- LT3680IDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3680IDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 3.5A 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:5,002
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Product details
Overview
LT3680IDD#TRPBF from Analog Devices is a 36V, 3.5A monolithic buck switching regulator with adjustable 200kHz–2.4MHz switching frequency, 75µA quiescent current in Burst Mode, and integrated 95mΩ bipolar NPN switch and boost Schottky diode. It delivers regulated 0.79V–30V output for automotive battery regulation and industrial power supplies.
For engineers reviewing the LT3680IDD#TRPBF datasheet, LT3680IDD#TRPBF pinout, LT3680IDD#TRPBF application, or LT3680IDD#TRPBF equivalent, key selection factors include its 3.5A continuous output capability, thermal protection, power good flag (PG), soft-start via RUN/SS pin, and compatibility with 3mm × 3mm DFN-10 package with exposed pad for low θJC = 10°C/W.
Technical Context
The LT3680IDD#TRPBF employs constant-frequency current-mode control with internal error amplifier (gm = 500 µMho) and slope compensation, enabling fast transient response and stable loop behavior across wide input (3.6V–36V) and output (0.79V–30V) ranges. Its VC pin provides direct access to the error amp output for external compensation.
It integrates a bipolar NPN power switch with 95mΩ saturation resistance and uses an external boost capacitor/diode network to drive the switch fully into saturation-critical for high-efficiency operation at high VIN/VOUT ratios. Frequency foldback reduces switching frequency during startup or overload to limit peak inductor current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 36V - supports 12V/24V automotive and industrial bus inputs without pre-regulation |
| Output Current | 3.5A continuous - sufficient for powering FPGA cores, microcontrollers, and analog subsystems |
| Quiescent Current | 75µA in Burst Mode - enables >10-year battery life in always-on IoT sensor nodes |
| Switching Frequency | 200kHz to 2.4MHz - adjustable via RT resistor; higher frequencies allow smaller inductors (e.g., 1MHz → 2.2µH typical) |
| Feedback Reference | 0.790V ±10mV - precise reference enables accurate output voltage setting with standard 1% resistors |
| Power Good Flag | Open-collector PG asserts when VOUT reaches 91% of target - provides reliable system power sequencing signal |
| Thermal Protection | Internal junction shutdown above 150°C - prevents damage during sustained overload or poor PCB heatsinking |
Pinout & Package
LT3680IDD#TRPBF is housed in a thermally enhanced 10-pin (3mm × 3mm) plastic DFN package with exposed pad (Pin 11), rated θJA = 45°C/W and θJC = 10°C/W. The exposed pad must be soldered to PCB ground plane for optimal thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (Pin 1) | Boost Diode Anode Connection | Supplies bias current to internal regulator; connects to Schottky diode anode for bootstrap drive |
| BOOST (Pin 2) | Bootstrap Drive Voltage Input | Provides >VIN voltage to fully saturate internal NPN switch; requires external capacitor and diode |
| SW (Pin 3) | Switch Node Output | Connects to inductor, catch diode cathode, and boost capacitor; carries high di/dt switching current |
| VIN (Pin 4) | Main Power Input | Supplies internal regulator and switch driver; requires local 10µF ceramic bypass |
| RUN/SS (Pin 5) | Enable & Soft-Start Control | Pull ≥2.5V for operation; RC network here sets controlled output voltage ramp rate |
| SYNC (Pin 6) | External Clock Synchronization | Accepts 250kHz–2MHz clock for EMI reduction; tie to GND for Burst Mode |
| PG (Pin 7) | Power Good Open-Collector Output | Sinks current when VOUT < 91% of regulation; requires external pull-up for logic-level signaling |
| FB (Pin 8) | Feedback Input | Regulated to 0.790V; connects to resistor divider for output voltage programming |
| VC (Pin 9) | Error Amplifier Output | Controls peak switch current; RC network to GND sets loop compensation |
| RT (Pin 10) | Oscillator Frequency Set | Resistor to GND selects switching frequency (200kHz–2.4MHz) per datasheet table |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Boost Schottky Diode | Eliminates external diode; reduces BOM count and layout area while maintaining >90% efficiency at 12VIN→5VOUT |
| Low-Ripple Burst Mode Operation | Maintains <15mVP-P output ripple at light loads while achieving 75µA IQ - critical for noise-sensitive analog circuits |
| Bias Current Sourcing from VOUT | Draws bias from output when VOUT > 3V - improves light-load efficiency by avoiding VIN-derived losses |
| Adjustable Switching Frequency | 200kHz–2.4MHz range allows trade-off between inductor size (smaller at high fSW) and efficiency (higher at low fSW) |
| Thermally Enhanced DFN Package | 3mm × 3mm footprint with exposed pad enables 3.5A operation at ≤65°C ambient without heatsink |
| Power Good Flag with Hysteresis | PG threshold offset = 65mV, hysteresis = 10mV - ensures clean, bounce-free power sequencing signals |
Applications
| Automotive Battery Regulation | Industrial Distributed Power |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery supply to 3.3V/5V for infotainment MCU and CAN transceivers under cold-crank (4.5V) and load-dump (40V) conditions. IC Role / Device Role / Timing Role: Primary step-down regulator with wide VIN range, thermal shutdown, and robust PG signaling for system reset coordination. Use Value: Maintains regulation down to 3.6V input and withstands 36V transients; 75µA IQ extends battery life during vehicle sleep mode. |
Use Scenario: Providing isolated 12V and 5V rails from a 24V factory automation bus to PLC I/O modules and fieldbus interfaces. IC Role / Device Role / Timing Role: High-current DC-DC converter with programmable frequency to avoid EMI conflicts with EtherCAT or PROFINET clocks. Use Value: 3.5A output supports multiple downstream LDOs; SYNC pin enables deterministic switching alignment across distributed power domains. |
| Portable Medical Device Power | Wall Adapter Replacement |
Use Scenario: Converting two Li-ion cells (6V–8.4V) to 3.3V for portable ultrasound front-end ASICs requiring ultra-low noise and long runtime. IC Role / Device Role / Timing Role: Efficient buck regulator operating in Burst Mode during standby, with soft-start preventing inrush into sensitive analog circuitry. Use Value: 75µA IQ enables multi-week battery life; low-ripple Burst Mode avoids audible noise in ceramic output capacitors near transducer drivers. |
Use Scenario: Replacing linear wall adapters in smart home hubs by stepping 12V PoE or 24V AC/DC adapter output to 5V USB power with minimal heat dissipation. IC Role / Device Role / Timing Role: High-efficiency switching regulator replacing inefficient linear regulators in space-constrained enclosures. Use Value: 95mΩ switch and integrated boost diode achieve >92% efficiency at full load; DFN package fits tight board areas without heatsinks. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610IMSE#TRPBF | 42V input, 3.5A, 2MHz sync rectified buck; 2.5µA IQ; requires external MOSFETs | No integrated switch or boost diode; higher efficiency at light loads but larger solution size | Choose for ultra-low IQ (<3µA) or higher VIN (>36V); avoid if minimizing BOM count is priority |
| TPS54360DDAR | 60V input, 3.5A, 100kHz–2.5MHz; 145µA IQ; no integrated boost diode; requires external bootstrap cap | Larger MSOP-8 package; lower max frequency stability; no BD pin for bias sourcing | Choose for >36V input tolerance; avoid if 75µA IQ or integrated boost diode are required |
Compared with LT3680IDD#TRPBF, LT8610IMSE#TRPBF offers lower quiescent current but demands external FETs and increases component count, while TPS54360DDAR supports higher input voltage but lacks integrated bias sourcing and has higher IQ-making LT3680IDD#TRPBF optimal for compact, efficient 36V-class designs where BOM simplicity matters.
Availability
LT3680IDD#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial distributed power, and portable medical device power requiring stable component supply and guaranteed long-term availability.
Supply support for LT3680IDD#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 (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, and automotive markets since 1965.
The LT3680IDD#TRPBF belongs to ADI's Power by Linear™ family of monolithic DC-DC regulators, engineered specifically for high-voltage industrial and automotive applications demanding robustness, low IQ, and minimal external components.
FAQ
What is the maximum input voltage rating for LT3680IDD#TRPBF?
The absolute maximum input voltage for LT3680IDD#TRPBF is 36V on the VIN pin. During normal regulation, transients up to 36V are acceptable regardless of switching frequency. However, under startup or overload, the safe maximum depends on frequency and duty cycle-per the equation VIN(MAX) = (VOUT + VD + VSW) / (fSW × tON(MIN)), where tON(MIN) ≈ 100ns. For 2.4MHz operation, keep VIN below ~20V in fault conditions.
Does LT3680IDD#TRPBF require an external Schottky diode?
No, LT3680IDD#TRPBF integrates a boost Schottky diode connection (BD pin) and internal bipolar NPN switch with bootstrap drive-eliminating the need for an external catch diode. The BD pin connects to the anode of an external Schottky diode used only for generating the BOOST voltage; the diode itself is not part of the main power path. This integration reduces component count and PCB area versus traditional buck controllers.
How is the output voltage programmed on LT3680IDD#TRPBF?
The output voltage of LT3680IDD#TRPBF is set using a resistor divider from VOUT to FB (Pin 8), which is regulated to 0.790V. Use R1 (top) and R2 (bottom) such that VOUT = 0.790V × (1 + R1/R2). For example, for 5V output: R2 = 10kΩ, R1 = 53.4kΩ (standard 1% values). The FB pin bias current is only 10–40nA, so resistor values can be large (e.g., 100kΩ–1MΩ) to minimize divider current without affecting accuracy.
What thermal derating applies to LT3680IDD#TRPBF in the DFN package?
LT3680IDD#TRPBF is rated for –40°C to +125°C junction temperature. In the 3mm × 3mm DFN package with properly soldered exposed pad, θJC = 10°C/W enables 3.5A operation at ≤65°C ambient with 2-layer PCB copper. Above 85°C ambient, output current must be reduced per the thermal derating curve in Figure 9 of the datasheet-e.g., at 100°C ambient, max continuous current drops to ~2.7A with 1-in² 2oz copper under the pad.
Can LT3680IDD#TRPBF synchronize to an external clock?
Yes, LT3680IDD#TRPBF supports external synchronization via the SYNC pin (Pin 6), accepting TTL/CMOS clock signals from 250kHz to 2MHz. Clock edges must have rise/fall times <1µs. When synchronized, the LT3680IDD#TRPBF locks its internal oscillator to the external source-enabling EMI reduction through frequency alignment across multiple converters in dense systems. Leaving SYNC floating is prohibited; tie to GND for standalone Burst Mode operation.
LT3680IDD#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):
- 36V
- Voltage - Output (Min/Fixed):
- 0.79V
- Voltage - Output (Max):
- 30V
- Current - Output:
- 3.5A
- Frequency - Switching:
- 230kHz ~ 2.45MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3680IDD#TRPBF FAQ
1.How can I place an order for LT3680IDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3680IDD#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 LT3680IDD#TRPBF reliable?
The price and inventory of LT3680IDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3680IDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3680IDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3680IDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3680IDD#TRPBF?
LT3680IDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3680IDD#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 LT3680IDD#TRPBF?
For technical support, including LT3680IDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3680IDD#TRPBF requirements.
6.How does Aetrix verify that LT3680IDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3680IDD#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 LT3680IDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3680IDD#TRPBF?
All LT3680IDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3680IDD#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 LT3680IDD#TRPBF part is unused and in its original packaging.
Return procedure for LT3680IDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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