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Analog Devices Inc. LT3680IMSE#PBF
- Part No.:
- LT3680IMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3680IMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 3.5A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,558
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Product details
Overview
LT3680IMSE#PBF from Analog Devices is a 36V, 3.5A monolithic step-down 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 in automotive battery regulation and industrial power supply applications.
For engineers reviewing the LT3680IMSE#PBF datasheet, LT3680IMSE#PBF pinout, LT3680IMSE#PBF application, or LT3680IMSE#PBF equivalent, key selection considerations include input voltage range (3.6V–36V), thermal performance in MSOP package, soft-start via RUN/SS pin, power good flag timing, and bias sourcing from BD pin above 3V.
Technical Context
The LT3680IMSE#PBF employs current-mode control with an internal error amplifier (gm = 500 µMho) and VC pin-based peak-current loop compensation. Its oscillator uses RT-pin resistor programming and includes frequency foldback during startup or overload to limit peak inductor current.
It integrates a bipolar NPN power switch driven by BOOST pin voltage (≥1.5V above SW), with BD pin supplying bias current to the internal regulator when VOUT > 3V-enabling efficiency enhancement at light loads. The PG pin asserts open-collector low until FB reaches 91% of 0.790V reference.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 36V - supports direct connection to 12V/24V automotive batteries and industrial rails without pre-regulation. |
| Max Output Current | 3.5A - sustained delivery into thermally managed PCB layout with exposed pad soldered. |
| Quiescent Current | 75µA at 12VIN/3.3VOUT in Burst Mode - enables always-on systems with multi-year battery life. |
| Switching Frequency | 200kHz to 2.4MHz - set by RT-to-GND resistor; higher frequencies allow smaller L/C but reduce max VIN/VOUT ratio. |
| Feedback Reference | 0.790V ±10mV - sets output voltage accuracy and enables precise resistor-divider programming from 0.79V to 30V. |
| Power Good Threshold | 91% of programmed VOUT - provides reliable system enable signaling with 65mV offset and 10mV hysteresis. |
| Thermal Range | –40°C to +125°C junction - rated for industrial and automotive under-hood environments. |
Pinout & Package
LT3680IMSE#PBF is housed in a 10-lead plastic MSOP package with exposed pad (Pin 11) that must be soldered to PCB ground for thermal and electrical integrity. θJA = 45°C/W, θJC = 10°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (Pin 1) | Boost Diode Anode Input | Connects to Schottky diode anode; supplies bias current to internal regulator when VOUT > 3V. |
| BOOST (Pin 2) | Switch Gate Drive Boost | Provides >VIN voltage to fully saturate internal bipolar NPN switch; requires external capacitor/diode network. |
| SW (Pin 3) | Switch Node Output | Drives inductor, catch diode cathode, and boost capacitor; carries high di/dt switching current. |
| VIN (Pin 4) | Main Power Input | Supplies internal regulator and switch; requires local 10µF ceramic bypass close to pin. |
| RUN/SS (Pin 5) | Enable & Soft-Start Control | Pull ≥2.5V for operation; tie RC network to generate controlled VOUT ramp; <0.2V disables regulator. |
| SYNC (Pin 6) | External Clock Input | Accepts 250kHz–2MHz clock for EMI reduction; grounded for Burst Mode operation. |
| PG (Pin 7) | Power Good Flag | Open-collector output active-low when VFB reaches 91% of target; valid only if VIN > 3.6V and RUN/SS high. |
| FB (Pin 8) | Feedback Input | Servo point for 0.790V reference; connects to resistor divider tap for output voltage programming. |
| VC (Pin 9) | Error Amplifier Output | Controls peak switch current; RC compensation network tied here sets loop stability. |
| RT (Pin 10) | Frequency Set Resistor | Resistor to GND programs switching frequency from 200kHz to 2.4MHz per datasheet table. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Boost Schottky Diode | Eliminates external diode, reducing BOM count and board area while enabling efficient bipolar switch drive. |
| Low-Ripple Burst Mode Operation | Maintains <15mVP-P output ripple at light loads with 75µA IQ, avoiding audible ceramic capacitor noise. |
| Adjustable Switch On/Off Timing | Minimum on-time ~80ns and off-time ~150ns enable wide VIN/VOUT ratios and support high-frequency designs. |
| Thermal Shutdown Protection | Automatically disables regulator if junction temperature exceeds safe limit, preventing permanent damage. |
| Soft-Start via RUN/SS Pin | RC-controlled voltage ramp on RUN/SS limits inrush current and prevents output overshoot during power-up. |
Applications
| Automotive Battery Regulation | Industrial Distributed Power |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery rail to 3.3V/5V for infotainment MCU and CAN transceivers under cold-crank (4.5V) and load-dump (36V) conditions. IC Role / Device Role / Timing Role: Primary buck converter providing stable, low-noise, thermally robust DC-DC conversion with power-good sequencing. Use Value: 3.6V–36V input range and –40°C to +125°C rating ensure uninterrupted operation across full automotive temperature and transient profile. |
Use Scenario: Point-of-load regulation in programmable logic controllers (PLCs) where multiple isolated 5V/12V rails feed I/O modules and communication interfaces. IC Role / Device Role / Timing Role: High-efficiency, compact step-down regulator delivering up to 3.5A with synchronized switching to minimize system-level EMI. Use Value: SYNC pin enables clock alignment across multiple LT3680IMSE#PBF units, reducing conducted noise peaks in dense industrial backplanes. |
| Portable Product Power | Wall Transformer Supply |
Use Scenario: Powering FPGA core and I/O banks in handheld test equipment using a single-cell Li-ion (3.0–4.2V) or dual-cell pack (6–8.4V) with minimal heat dissipation. IC Role / Device Role / Timing Role: Adjustable-output buck regulator with BD-pin bias sourcing to maintain high efficiency down to µA load currents. Use Value: 75µA quiescent current in Burst Mode extends battery runtime; soft-start prevents brownout during wake-up transitions. |
Use Scenario: Replacing linear regulators in AC/DC wall adapters to improve efficiency and reduce thermal derating at 5V/3A output with 9–36V DC input. IC Role / Device Role / Timing Role: High-current, thermally enhanced buck controller converting unregulated DC bus to tightly regulated low-voltage output. Use Value: Exposed-pad MSOP package enables direct thermal coupling to heatsink or copper pour, sustaining 3.5A continuous output without fan cooling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3630EMSE#PBF | Lower max input (15V), lower IOUT (1.5A), no integrated boost diode, 3mm × 4mm MSOP. | Better suited for low-input, space-constrained DC-DC where 36V capability is unnecessary. | Select when input never exceeds 15V and thermal budget allows discrete boost diode placement. |
| MP2451DT-LF-Z | 36V input, 0.6A output, no PG flag, no SYNC, 8-pin SOIC, higher IQ (120µA). | Cost-optimized for non-critical, low-current auxiliary rails where sequencing and EMI control are secondary. | Choose for simple, low-cost 36V-to-5V/3.3V conversion without power-good monitoring or synchronization needs. |
Compared with LTC3630EMSE#PBF and MP2451DT-LF-Z, the LT3680IMSE#PBF uniquely combines 36V/3.5A capability, integrated boost diode, power good flag, and synchronization-making it optimal for demanding industrial and automotive primary power rails requiring reliability, density, and system-level control.
Availability
LT3680IMSE#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 and long production lifecycles.
Supply support for LT3680IMSE#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 precision instrumentation, industrial automation, and automotive markets.
The LT3680IMSE#PBF belongs to ADI's Power by Linear™ family of monolithic DC-DC regulators, designed specifically for high-input-voltage, high-reliability power conversion in harsh environments with minimal external components.
FAQ
What is the maximum input voltage rating for LT3680IMSE#PBF?
The absolute maximum input voltage at the VIN pin is 36V. However, safe continuous operation depends on switching frequency and duty cycle constraints. At 2.4MHz, the practical maximum input is reduced due to minimum on-time limitations; for 36V operation, frequencies ≤600kHz are recommended per the datasheet's VIN(MAX) equation. Transient overvoltage up to 36V is acceptable during regulation if no start-up or overload events occur.
Does LT3680IMSE#PBF require an external Schottky diode?
No, the LT3680IMSE#PBF integrates a boost Schottky diode internally-connected to the BD pin-and does not require an external catch diode. However, an external Schottky diode is still required between SW and GND (cathode to SW, anode to GND) to provide the freewheeling path during switch-off time. This external diode must withstand full input voltage and conduct average output current.
How is the output voltage programmed on LT3680IMSE#PBF?
The output voltage is programmed using a resistor divider between VOUT and GND, with the FB pin connected to the divider midpoint. The LT3680IMSE#PBF regulates FB to 0.790V, so VOUT = 0.790V × (1 + R1/R2). For example, to set 5V output, use R1 = 53.6kΩ and R2 = 10kΩ (1% tolerance). The feedback network must be routed away from noisy nodes to avoid regulation errors.
What thermal design considerations apply to LT3680IMSE#PBF in MSOP package?
The LT3680IMSE#PBF MSOP package features an exposed pad (Pin 11) that must be soldered to a minimum 100mm² copper thermal pad on the PCB, connected to internal ground planes via ≥4 thermal vias (0.3mm diameter). With this layout, θJA is 45°C/W, enabling 3.5A continuous output at +85°C ambient. Without proper thermal pad connection, junction temperature rise exceeds safe limits rapidly under full load.
Can LT3680IMSE#PBF synchronize to an external clock?
Yes, the LT3680IMSE#PBF supports external clock synchronization via the SYNC pin (Pin 6), accepting TTL/CMOS-compatible signals from 250kHz to 2MHz. When synchronized, the internal oscillator locks to the external clock edge, eliminating beat frequencies and reducing EMI peaks. The SYNC pin must not be left floating; tie to GND for standalone Burst Mode operation.
LT3680IMSE#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):
- 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-MSOP-EP
LT3680IMSE#PBF FAQ
1.How can I place an order for LT3680IMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3680IMSE#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 LT3680IMSE#PBF reliable?
The price and inventory of LT3680IMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3680IMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3680IMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3680IMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3680IMSE#PBF?
LT3680IMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3680IMSE#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 LT3680IMSE#PBF?
For technical support, including LT3680IMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3680IMSE#PBF requirements.
6.How does Aetrix verify that LT3680IMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3680IMSE#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 LT3680IMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3680IMSE#PBF?
All LT3680IMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3680IMSE#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 LT3680IMSE#PBF part is unused and in its original packaging.
Return procedure for LT3680IMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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