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Analog Devices Inc. LT3685IMSE#TRPBF
- Part No.:
- LT3685IMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3685IMSE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 2A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:7,503
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Product details
Overview
LT3685IMSE#TRPBF from Analog Devices is a 36V, 2A, 2.4MHz monolithic step-down switching regulator with integrated 0.25Ω bipolar NPN switch and boost Schottky diode. It operates from 3.6V to 36V input, withstands 60V transients via overvoltage lockout, delivers 0.79V–20V adjustable output, and features power good flag and soft-start. It targets automotive battery regulation and industrial distributed supplies.
For engineers reviewing the LT3685IMSE#TRPBF datasheet, LT3685IMSE#TRPBF pinout, LT3685IMSE#TRPBF application, or LT3685IMSE#TRPBF equivalent, key selection criteria include its 2A continuous output current, 200kHz–2.4MHz adjustable switching frequency, 0.790V feedback reference, integrated boost diode, and thermal performance in the 10-lead MSOP package with exposed pad.
Technical Context
The LT3685IMSE#TRPBF uses constant-frequency current-mode control with an external RT resistor setting oscillator frequency from 200kHz to 2.4MHz. Its internal error amplifier drives the VC pin to regulate peak switch current, while active clamp on VC provides current limiting and soft-start coordination via RUN/SS ramping.
It integrates a bipolar NPN power switch with 0.25Ω typical RCE(SAT), a boost capacitor drive path (BOOST/BD pins) enabling full saturation, and overvoltage protection that disables switching above 36V (min) VIN while sustaining 60V transients. Power good (PG) asserts when FB reaches 89% of 0.790V reference.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 36V operation; survives 60V non-repetitive transients via OVP shutdown |
| Output Current | 2A continuous; switch current limit 3.2A–4.2A depending on duty cycle |
| Switching Frequency | Adjustable 200kHz–2.4MHz via RT resistor; supports synchronization 250kHz–2MHz |
| Feedback Reference | 0.790V ±10mV; enables precise output voltage programming from 0.79V to 20V |
| Shutdown Current | <1µA at VIN; achieved by pulling RUN/SS low |
| Thermal Package | 10-lead MSOP with exposed pad; θJA = 45°C/W, θJC = 10°C/W |
| Power Good Threshold | FB = 89% of 0.790V (≈703mV); open-collector PG output valid above 3.6V VIN and RUN/SS high |
Pinout & Package
The LT3685IMSE#TRPBF is housed in a 10-lead plastic MSOP package with exposed pad (Pin 11), which must be soldered to PCB for thermal and electrical grounding. Package dimensions: 3mm × 3mm × 1.1mm body height, 0.5mm lead pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (1) | Boost Diode Anode Supply | Connects to anode of external Schottky; supplies bias current to internal regulator when >3V |
| BOOST (2) | Switch Drive Boost Node | Provides voltage higher than VIN to fully saturate internal bipolar NPN switch |
| SW (3) | Switch Output | Drives external inductor and catch diode; connects to boost capacitor |
| VIN (4) | Main Input Supply | Supplies internal regulator and power switch; bypass locally with ≥4.7µF ceramic |
| RUN/SS (5) | Enable & Soft-Start Control | Pull low for <1µA shutdown; apply RC ramp for controlled VOUT rise |
| SYNC (6) | External Clock Input | Accepts 250kHz–2MHz square wave for frequency synchronization |
| PG (7) | Power Good Flag | Open-collector output asserting when VOUT reaches 89% of programmed value |
| FB (8) | Feedback Input | Regulated to 0.790V; connects to resistor divider tap for output voltage setting |
| VC (9) | Error Amplifier Output | Controls peak switch current; used for loop compensation with RC network to GND |
| RT (10) | Oscillator Frequency Set | Resistor to GND sets switching frequency (200kHz–2.4MHz) |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Boost Schottky Diode | Eliminates external boost diode; reduces BOM count and layout area in buck topology |
| Saturating Bipolar NPN Switch | 0.25Ω typical RCE(SAT) enables high efficiency at 2A without MOSFET gate drive complexity |
| Overvoltage Lockout (OVP) | Disables switching at VIN >36V (min); allows safe 60V transient tolerance in automotive and industrial environments |
| Adjustable Frequency with SYNC | Enables EMI optimization and noise avoidance via RT tuning or external clock locking |
| Thermally Enhanced MSOP | Exposed pad lowers thermal resistance (θJC = 10°C/W), supporting 2A continuous load in compact space-constrained designs |
Applications
| Automotive Battery Regulation | Industrial Distributed Supply |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery rail to 3.3V or 5V for infotainment ECUs and ADAS sensors under cold-crank and load-dump conditions. IC Role / Device Role / Timing Role: Primary step-down regulator providing stable, transient-hardened DC output with 60V surge tolerance and power-good signaling. Use Value: Eliminates need for external OVP circuitry and discrete boost diode, reducing solution size and improving reliability in harsh automotive environments. | Use Scenario: Generating local 5V/12V rails from 24V/36V factory automation bus for PLC I/O modules and sensor interfaces. IC Role / Device Role / Timing Role: High-input-voltage buck converter delivering 2A with adjustable frequency to avoid noise coupling into analog signal chains. Use Value: Enables compact, thermally efficient design using small inductors (e.g., 4.7µH @ 800kHz) and ceramic capacitors, meeting industrial EMC requirements. |
| Set Top Box Power | Wall Transformer Regulation |
Use Scenario: Converting 12V–19V adapter output to 3.3V/1.8V for SoC and memory in consumer STB platforms with strict standby power limits. IC Role / Device Role / Timing Role: Main DC-DC converter with ultra-low shutdown current (<1µA) and soft-start to prevent inrush during hot-plug events. Use Value: Meets Energy Star standby power requirements while maintaining fast transient response for burst-mode video processing loads. | Use Scenario: Replacing linear regulators in universal AC/DC wall adapters to improve efficiency and reduce heat in 5V/2A USB-C PD accessory supplies. IC Role / Device Role / Timing Role: High-efficiency buck controller accepting wide input range (up to 36V) and delivering tightly regulated output with minimal external components. Use Value: Achieves >85% efficiency across load range without heatsink, enabling smaller adapter form factors and lower no-load power consumption. |
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), higher switching frequency (up to 4MHz), MOSFET-based, no integrated boost diode | Better suited for low-input, high-density point-of-load; lacks 60V transient tolerance and BD pin functionality | Select when input is ≤15V and board space is critical; requires external boost diode and gate driver support |
| LM5164QPWPRQ1 | Wider input (3V–65V), 1.5A output, integrated MOSFETs, no BD/BOOST pins, AEC-Q100 qualified | Designed for automotive systems requiring qualification; lacks programmable frequency and soft-start flexibility of LT3685IMSE#TRPBF | Choose for automotive production where AEC-Q100 compliance is mandatory; trade off adjustability for qualification and higher VIN capability |
Compared with LTC3630EMSE#PBF and LM5164QPWPRQ1, the LT3685IMSE#TRPBF uniquely combines 60V transient survivability, integrated boost diode, and 2A output in a thermally optimized MSOP - making it optimal for unqualified but rugged industrial and automotive auxiliary supplies where layout simplicity and surge robustness are prioritized over automotive qualification or ultra-high frequency.
Availability
LT3685IMSE#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial distributed supply, and wall transformer regulation requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT3685IMSE#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3685IMSE#TRPBF belongs to the LT® monolithic switching regulator product line, designed specifically for rugged, high-input-voltage DC-DC conversion in space- and thermal-constrained environments where reliability under voltage transients is critical.
FAQ
What is the maximum input voltage the LT3685IMSE#TRPBF can safely withstand?
The LT3685IMSE#TRPBF has overvoltage lockout that disables switching when VIN exceeds 36V (minimum) - typically 38V - allowing it to safely withstand non-repetitive 60V transients for up to 1 second. Continuous operation is rated up to 36V. This makes LT3685IMSE#TRPBF suitable for automotive load-dump and industrial surge environments without external protection circuitry.
Does the LT3685IMSE#TRPBF require an external boost diode?
No, the LT3685IMSE#TRPBF integrates a boost Schottky diode internally. The BD pin connects to the anode of this diode, eliminating the need for an external component. This integration reduces bill-of-materials count, PCB area, and potential failure points - a key differentiator versus controllers requiring external bootstrap diodes.
What is the function of the VC pin on the LT3685IMSE#TRPBF?
The VC pin on the LT3685IMSE#TRPBF is the output of the internal error amplifier and directly controls peak switch current. It serves as the control node for loop compensation: an RC network from VC to GND sets phase margin and transient response. The VC pin also features an active clamp tied to RUN/SS, enabling coordinated soft-start behavior in the LT3685IMSE#TRPBF.
Can the LT3685IMSE#TRPBF synchronize to an external clock?
Yes, the LT3685IMSE#TRPBF supports external clock synchronization via the SYNC pin, accepting square-wave inputs from 250kHz to 2MHz. This allows noise-sensitive systems to align switching frequency with other converters or avoid critical EMI bands - a capability confirmed in the Electrical Characteristics table and Applications Information section of the LT3685IMSE#TRPBF datasheet.
What package type and thermal characteristics does the LT3685IMSE#TRPBF use?
The LT3685IMSE#TRPBF uses a 10-lead plastic MSOP package with exposed pad (Pin 11 = GND), measuring 3mm × 3mm. Its thermal resistance is θJA = 45°C/W and θJC = 10°C/W when the exposed pad is properly soldered to PCB copper. This enables reliable 2A continuous operation in compact industrial and automotive layouts without additional heatsinking.
LT3685IMSE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) 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):
- 20V
- Current - Output:
- 2A
- Frequency - Switching:
- 200kHz ~ 2.4MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LT3685IMSE#TRPBF FAQ
1.How can I place an order for LT3685IMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3685IMSE#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 LT3685IMSE#TRPBF reliable?
The price and inventory of LT3685IMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3685IMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3685IMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3685IMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3685IMSE#TRPBF?
LT3685IMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3685IMSE#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 LT3685IMSE#TRPBF?
For technical support, including LT3685IMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3685IMSE#TRPBF requirements.
6.How does Aetrix verify that LT3685IMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3685IMSE#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 LT3685IMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3685IMSE#TRPBF?
All LT3685IMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3685IMSE#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 LT3685IMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3685IMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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