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Analog Devices Inc. LT3680IDD#PBF
- Part No.:
- LT3680IDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3680IDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 3.5A 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:238
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Product details
Overview
LT3680IDD#PBF from Analog Devices is a 36V, 3.5A monolithic buck switching regulator with adjustable switching frequency (200kHz–2.4MHz), 75µA quiescent current in Burst Mode, integrated 95mΩ NPN switch and boost Schottky diode, and power good flag - used in automotive battery regulation and industrial distributed supplies.
For engineers reviewing the LT3680IDD#PBF datasheet, LT3680IDD#PBF pinout, LT3680IDD#PBF application, or LT3680IDD#PBF equivalent, key selection criteria include input voltage range (3.6V–36V), output voltage adjustability (0.79V–30V), thermal performance in DFN package, soft-start control via RUN/SS, and synchronization capability (250kHz–2MHz).
Technical Context
The LT3680IDD#PBF employs constant-frequency current-mode control with RT-resistor-programmable oscillator (200kHz–2.4MHz) and internal slope compensation. Its bipolar NPN switch is driven by a BOOST pin voltage higher than VIN, enabled by an external boost capacitor and Schottky diode.
It integrates a 0.790V precision feedback reference, VC error amplifier with 500µ℧ transconductance, and active current-limit clamping. Power good (PG) asserts when FB reaches 91% of regulation, and low-ripple Burst Mode maintains efficiency at light loads while limiting output ripple to <15mVP-P.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 36V - supports wide-range industrial and automotive inputs without pre-regulation |
| Max Output Current | 3.5A - delivers full rated load with thermal derating managed via exposed pad |
| Quiescent Current | 75µA at 12VIN/3.3VOUT in Burst Mode - enables long battery life in portable systems |
| Switch On-Resistance | 95mΩ - reduces conduction loss and improves efficiency at high load currents |
| Feedback Reference | 0.790V ±10mV - enables precise output voltage setting from 0.79V to 30V using resistor divider |
| Switching Frequency | 200kHz to 2.4MHz - selectable via RT resistor; higher frequencies allow smaller magnetics |
| Power Good Threshold | 91% of VOUT - provides reliable system sequencing and fault detection |
Pinout & Package
LT3680IDD#PBF is housed in a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) soldered to PCB for low θJA = 45°C/W and θJC = 10°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (Pin 1) | Boost Diode Anode Connection | Supplies bias current to internal regulator; must connect to Schottky diode anode |
| BOOST (Pin 2) | Switch Gate Drive Boost Node | Provides >VIN voltage to fully saturate internal NPN switch; requires external boost cap |
| SW (Pin 3) | Switch Output Node | Connects to inductor, catch diode cathode, and boost capacitor; carries high di/dt current |
| VIN (Pin 4) | Main Input Supply | Supplies power to internal regulator and switch; requires local 10µF ceramic bypass |
| RUN/SS (Pin 5) | Enable & Soft-Start Control | Logic-level enable (≥2.5V = on); RC network here sets controlled VOUT ramp rate |
| SYNC (Pin 6) | External Clock Input | Accepts 250kHz–2MHz clock for EMI reduction; must not float; fast edge required |
| PG (Pin 7) | Open-Drain Power Good Flag | Active-low signal valid only when VIN > 3.6V and RUN/SS high; pulled up externally |
| FB (Pin 8) | Feedback Input | Regulated to 0.790V; connects to resistor divider tap for output voltage programming |
| VC (Pin 9) | Error Amplifier Output | Controls peak switch current; RC compensation network tied here stabilizes loop |
| RT (Pin 10) | Oscillator Frequency Set | Resistor to GND programs switching frequency; 8.66kΩ = 2.4MHz, 187kΩ = 200kHz |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Boost Schottky Diode | Eliminates external boost diode; reduces BOM count and layout area in compact DFN |
| Low-Ripple Burst Mode Operation | Maintains <15mVP-P output ripple at light loads while achieving 75µA IQ |
| Output Bias Current Sourcing | Draws bias from VOUT when >3V, improving light-load efficiency over VIN-only bias |
| Thermal Protection | Internal shutdown at junction temperature >150°C; resumes operation after cooldown |
| Synchronizable Frequency | Locks to external clock (250kHz–2MHz) to eliminate beat frequencies and reduce EMI |
Applications
| Automotive Battery Regulation | Industrial Distributed Supply |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery rail to stable 3.3V or 5V for infotainment MCU and sensors. IC Role / Device Role / Timing Role: Primary step-down regulator handling cold-crank (4.5V) to load-dump (36V) transients. Use Value: 3.6V–36V input range and thermal robustness ensure uninterrupted operation across automotive voltage extremes. |
Use Scenario: Providing isolated 12V/15V rails in programmable logic controllers and I/O modules. IC Role / Device Role / Timing Role: High-current DC-DC converter powering FPGA core, ADCs, and communication interfaces. Use Value: 3.5A output and 95mΩ switch minimize heat rise in confined industrial enclosures. |
| Portable Product Power | Wall Transformer Regulation |
Use Scenario: Converting 9V–24V wall adapter or Li+ battery pack to 3.3V for handheld test equipment. IC Role / Device Role / Timing Role: Efficient main power supply enabling >10-hour runtime via 75µA Burst Mode IQ. Use Value: Low quiescent current extends battery life; soft-start prevents inrush into capacitive loads. |
Use Scenario: Replacing linear regulators in AC/DC adapter secondary-side post-regulation stages. IC Role / Device Role / Timing Role: High-efficiency buck stage improving overall adapter efficiency and reducing thermal stress. Use Value: 95mΩ switch and integrated boost diode reduce component count and improve reliability vs. discrete solutions. |
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, 3A max, 3mm × 4mm MSOP, no integrated boost diode, 100µA IQ | Requires external boost diode; lower max current; better suited for space-constrained non-automotive designs | Choose when board area allows external diode and 3A suffices; avoid if 36V+ transients expected |
| MP2451DT-LF-Z | 36V input, 2A max, 8-pin SOIC, no PG flag, 100µA IQ, no SYNC | Lacks power good signaling and synchronization; simpler feature set for cost-sensitive industrial use | Select for basic step-down where PG and EMI control are unnecessary; verify thermal margin at 2A |
Compared with LTC3630EMSE#PBF and MP2451DT-LF-Z, the LT3680IDD#PBF offers higher output current (3.5A), integrated boost diode, power good flag, and synchronization - making it optimal for automotive and noise-sensitive industrial applications requiring full feature integration in minimal footprint.
Availability
LT3680IDD#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial distributed supply, and portable product power applications requiring stable component supply, extended temperature operation (–40°C to 125°C), and long-term production continuity.
Supply support for LT3680IDD#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 (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3680IDD#PBF belongs to ADI's Power by Linear™ family of monolithic DC/DC regulators, engineered for high-voltage industrial and automotive power conversion with emphasis on efficiency, thermal resilience, and functional integration.
FAQ
What is the maximum input voltage rating for LT3680IDD#PBF?
The LT3680IDD#PBF has an absolute maximum VIN rating of 36V. It operates continuously across 3.6V to 36V input range. During startup or overload, safe operation depends on switching frequency and minimum on-time; for sustained 36V input, ensure the device is in regulation and not pulse-skipping under transient conditions. The BOOST pin withstands up to 56V, supporting robust gate drive above VIN.
Does LT3680IDD#PBF require an external boost diode?
No, the LT3680IDD#PBF integrates the boost Schottky diode function internally - the BD pin connects directly to the anode of the internal diode. No external boost diode is needed, simplifying design and reducing component count. However, an external Schottky diode is still required as the catch diode between SW and GND.
How is the switching frequency set on LT3680IDD#PBF?
The switching frequency of LT3680IDD#PBF is set by connecting a resistor (RT) from Pin 10 (RT) to GND. Values range from 8.66kΩ (2.4MHz) to 187kΩ (200kHz). The relationship is nonlinear and documented in the datasheet's Figure 1. Frequency accuracy is ±10% over temperature and line, and the part supports external synchronization from 250kHz to 2MHz via the SYNC pin.
What thermal performance can be expected from LT3680IDD#PBF in its DFN package?
The LT3680IDD#PBF in the 3mm × 3mm DFN package achieves θJA = 45°C/W and θJC = 10°C/W when the exposed pad (Pin 11) is properly soldered to a thermal pad on the PCB. At 3.5A output and 12VIN/3.3VOUT, typical junction temperature rise is ~40°C above ambient with 2-in² 2-oz copper, enabling reliable operation up to +125°C ambient in well-designed layouts.
Can LT3680IDD#PBF operate in dropout or near-dropout conditions?
The LT3680IDD#PBF does not operate in true dropout mode like LDOs; it requires minimum duty cycle dictated by tON(MIN) ≈ 80ns. Minimum input voltage is calculated as VIN(MIN) = VOUT/(1 – fSW × tOFF(MIN)). At 2.4MHz, VIN(MIN) rises to ~4.2V for 3.3V output. For lowest dropout, use lower fSW (e.g., 200kHz) and ensure sufficient tOFF(MIN) margin per datasheet equations.
LT3680IDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN 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):
- 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#PBF FAQ
1.How can I place an order for LT3680IDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3680IDD#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 LT3680IDD#PBF reliable?
The price and inventory of LT3680IDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3680IDD#PBF is usually 5 days.
3.What payment methods are accepted for LT3680IDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3680IDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3680IDD#PBF?
LT3680IDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3680IDD#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 LT3680IDD#PBF?
For technical support, including LT3680IDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3680IDD#PBF requirements.
6.How does Aetrix verify that LT3680IDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3680IDD#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 LT3680IDD#PBF meets industry standards.
7.What is the process for return or replacement of LT3680IDD#PBF?
All LT3680IDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3680IDD#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 LT3680IDD#PBF part is unused and in its original packaging.
Return procedure for LT3680IDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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