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Analog Devices Inc. LT3680EDD#PBF
- Part No.:
- LT3680EDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3680EDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 3.5A 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:771
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Product details
Overview
LT3680EDD#PBF 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 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 LT3680EDD#PBF datasheet, LT3680EDD#PBF pinout, LT3680EDD#PBF application, or LT3680EDD#PBF equivalent, key selection factors include its 3.5A continuous output capability, thermal protection, power good flag signaling at 91% VOUT, soft-start via RUN/SS ramp, and compatibility with ceramic output capacitors due to current-mode control.
Technical Context
The LT3680EDD#PBF implements constant-frequency current-mode PWM control with RT-resistor programmable oscillator (200kHz–2.4MHz), internal error amplifier (500 µ℧ gm), and VC-pin-based peak-current loop compensation. Its bipolar NPN switch is driven by a BOOST-capacitor-boosted gate drive, enabling full saturation at high input voltages.
It features low-ripple Burst Mode operation (≤15mVP-P) with bias current drawn from VOUT when >3V, frequency foldback during startup/overload, and active VC clamping for current limiting. The PG open-collector flag asserts when FB reaches 91% of 0.790V reference, valid only when VIN > 3.6V and RUN/SS is high.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 36V - supports wide-range industrial and automotive inputs without external pre-regulation |
| Max Output Current | 3.5A continuous - enables single-chip 5V/3.3V supply for FPGA I/O banks or microcontroller subsystems |
| Quiescent Current | 75µA at 12VIN/3.3VOUT in Burst Mode - extends battery life in always-on portable systems |
| Switch On-Resistance | 95mΩ - reduces conduction loss and thermal rise at full load in compact DFN package |
| Feedback Reference | 0.790V ±15mV - enables precise output setting from 0.79V to 30V using standard resistor ratios |
| Power Good Threshold | 91% of programmed VOUT - provides reliable system reset timing without external monitoring circuitry |
| Thermal Shutdown | Active at TJ > ~160°C - protects device during sustained overload or poor PCB heatsinking |
Pinout & Package
LT3680EDD#PBF is housed in a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) soldered to PCB ground for 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 anode of external Schottky diode |
| BOOST (Pin 2) | Boost Capacitor Drive Node | Provides >VIN voltage to saturate NPN switch; requires external capacitor to SW |
| SW (Pin 3) | Switch Node | Connects to inductor, catch diode cathode, and BOOST capacitor; carries high di/dt switching current |
| VIN (Pin 4) | Main Input Supply | Supplies power to internal regulator and switch; requires local 10µF X7R ceramic bypass |
| RUN/SS (Pin 5) | Enable & Soft-Start Control | Shuts down device when <0.2V; ramps output voltage when RC network applied |
| SYNC (Pin 6) | External Clock Input | Accepts 250kHz–2MHz clock for EMI reduction; must not float |
| PG (Pin 7) | Power Good Flag | Open-collector output pulled high externally; asserts when VOUT ≥ 91% of target |
| 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 network here sets loop compensation |
| RT (Pin 10) | Frequency Set Resistor | Resistor to GND programs switching frequency from 200kHz to 2.4MHz |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Boost Schottky Diode Driver | Eliminates need for external bootstrap diode; enables efficient NPN switch saturation up to 36V input |
| Burst Mode Operation | Maintains ≤15mVP-P output ripple while achieving 75µA IQ at light loads |
| Output Bias Current Sourcing | Draws bias from VOUT when >3V, improving light-load efficiency without auxiliary winding |
| Thermally Enhanced DFN Package | 3mm × 3mm footprint with exposed GND pad enables high-power density in space-constrained designs |
| Current-Mode Control Architecture | Enables stable operation with zero-ESR ceramic output capacitors and fast transient response |
Applications
| Automotive Battery Regulation | Industrial Distributed Power |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery to 3.3V/5V for infotainment ECUs under cold-crank (4.5V) and load-dump (36V) conditions. IC Role / Device Role / Timing Role: Primary step-down regulator with wide VIN tolerance, thermal shutdown, and power good signaling for safe MCU boot sequencing. Use Value: Eliminates need for external TVS or pre-regulator; 75µA IQ meets ISO 16750-2 quiescent current requirements for parked mode. |
Use Scenario: Providing isolated 12V-to-5V conversion for PLC I/O modules operating in 0°C–70°C ambient with 36V field wiring. IC Role / Device Role / Timing Role: High-reliability DC/DC converter with integrated switch, thermal protection, and SYNC input for synchronized multi-rail noise reduction. Use Value: 3.5A output supports multiple isolated RS-485 transceivers; DFN package allows dense board layout without heatsink. |
| Portable Product Power | Wall Transformer Regulation |
Use Scenario: Converting 9V–24V wall adapter output to 3.3V for handheld medical devices requiring >100-hour battery backup. IC Role / Device Role / Timing Role: Efficient buck regulator with Burst Mode and soft-start to minimize inrush and extend runtime. Use Value: 75µA no-load IQ directly extends Li-ion battery life; RUN/SS-controlled soft-start prevents brownout during wake-up. |
Use Scenario: Replacing linear regulators in legacy AC/DC adapters to improve efficiency and reduce heat in enclosed enclosures. IC Role / Device Role / Timing Role: High-input-voltage buck controller accepting up to 36V DC input from unregulated rectified outputs. Use Value: 95mΩ switch and integrated boost diode driver achieve >90% efficiency at 2A, reducing thermal derating 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 |
|---|---|---|---|
| LT8610EMSE#PBF | 42V input, 3.5A, 2MHz sync capability, 2.5µA IQ, requires external bootstrap diode | Superior light-load efficiency but lacks integrated boost diode driver; higher cost | Choose for ultra-low IQ (<3µA) in battery-critical apps where external diode is acceptable |
| MP2451DT-LF-Z | 36V input, 0.6A, 2MHz, 120µA IQ, no PG flag or SYNC, SOIC-8 package | Limited output current and missing PG/SYNC; lower thermal performance | Choose only for cost-sensitive, low-current (<0.6A) applications where feature set is secondary |
Compared with LT3680EDD#PBF, LT8610EMSE#PBF offers significantly lower quiescent current but requires external components and lacks integrated boost drive, while MP2451DT-LF-Z sacrifices current capability, monitoring features, and thermal performance for lower unit cost.
Availability
LT3680EDD#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial distributed power, and portable product power applications requiring stable component supply across extended temperature ranges (–40°C to 125°C).
Supply support for LT3680EDD#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3680EDD#PBF belongs to Analog Devices' monolithic power management IC family, designed specifically for high-input-voltage, high-efficiency buck conversion in harsh environments where reliability, thermal performance, and integration are critical.
FAQ
What is the maximum input voltage rating for LT3680EDD#PBF?
The absolute maximum input voltage for LT3680EDD#PBF 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 minimum on-time; for example, at 2.4MHz, VIN(MAX) is limited to ~24V to avoid violating tON(MIN) constraints. Always verify against the VIN vs. fSW design equations in the datasheet.
Does LT3680EDD#PBF require an external bootstrap diode?
No, LT3680EDD#PBF does not require an external bootstrap diode. It integrates a boost Schottky diode driver and relies on an external Schottky diode connected between BD and SW pins to generate the BOOST voltage. The BD pin supplies bias current to the internal regulator, and the BOOST pin drives the NPN switch base-no separate bootstrap diode is needed.
What is the function of the exposed pad on the LT3680EDD#PBF DFN package?
The exposed pad (Pin 11) on the LT3680EDD#PBF is electrically and thermally connected to GND. It must be soldered to a PCB copper pour to achieve the specified θJA = 45°C/W and θJC = 10°C/W thermal resistance. Failure to solder the pad degrades thermal performance and may cause premature thermal shutdown under 3.5A load.
Can LT3680EDD#PBF operate with ceramic output capacitors?
Yes, LT3680EDD#PBF is fully compatible with ceramic output capacitors due to its current-mode control architecture, which does not rely on capacitor ESR for stability. A typical design uses ≥10µF X7R/X5R ceramics. However, audible noise may occur in Burst Mode at very light loads; if unacceptable, add a small tantalum or polymer capacitor in parallel.
How is the power good (PG) flag triggered on LT3680EDD#PBF?
The PG flag on LT3680EDD#PBF is an open-collector output that goes high-impedance when the FB pin voltage reaches 91% of the 0.790V reference (i.e., 91% × 0.790V ≈ 0.72V). It is valid only when VIN > 3.6V and RUN/SS is high. An external pull-up resistor (e.g., 10kΩ to 3.3V) is required to generate a logic-high signal indicating regulated output.
LT3680EDD#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)
LT3680EDD#PBF FAQ
1.How can I place an order for LT3680EDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3680EDD#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 LT3680EDD#PBF reliable?
The price and inventory of LT3680EDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3680EDD#PBF is usually 5 days.
3.What payment methods are accepted for LT3680EDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3680EDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3680EDD#PBF?
LT3680EDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3680EDD#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 LT3680EDD#PBF?
For technical support, including LT3680EDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3680EDD#PBF requirements.
6.How does Aetrix verify that LT3680EDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3680EDD#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 LT3680EDD#PBF meets industry standards.
7.What is the process for return or replacement of LT3680EDD#PBF?
All LT3680EDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3680EDD#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 LT3680EDD#PBF part is unused and in its original packaging.
Return procedure for LT3680EDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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