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Analog Devices Inc. LT3663IDCB
- Part No.:
- LT3663IDCB
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LT3663IDCB.pdf
- Description:
- IC REG BUCK ADJ 1.2A 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,941
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Product details
Overview
LT3663IDCB from Analog Devices (formerly Linear Technology) is a 1.5MHz fixed-frequency, current-mode step-down switching regulator with programmable output current limit (0.4A–1.2A), 7.5V–36V input range, and integrated boost diode. It delivers up to 1.2A at 5V or 3.3V fixed outputs and is used in automotive battery regulation, industrial 24V supplies, and wall adapter-powered systems requiring precise power dissipation control.
For engineers reviewing the LT3663IDCB datasheet, LT3663IDCB pinout, LT3663IDCB application, or LT3663IDCB equivalent, key selection criteria include its 8-lead DFN (2mm × 3mm) thermally enhanced package, internal compensation, 275mV switch VCE(SAT) at 1A, overvoltage lockout (39V typ.), and thermal shutdown - all critical for high-reliability 12V/24V embedded power rails.
Technical Context
The LT3663IDCB implements peak current mode control with a 1.5MHz oscillator and internal slope compensation, enabling stable operation without external loop compensation. Its servo-based output current limit circuit uses an external resistor on the ILIM pin to set average inductor current between 0.4A and 1.2A, directly constraining system power dissipation.
It integrates a bipolar NPN power switch with BOOST pin drive (via internal diode + external capacitor), allowing full saturation across the 7.5V–36V input range. Input protection includes undervoltage lockout (7.5V rising) and overvoltage lockout (39V rising), with transient tolerance up to 60V - making it suitable for unregulated automotive and industrial sources.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 7.5V to 36V continuous; withstands 60V nonrepetitive transients - supports direct connection to 12V/24V vehicle batteries and industrial supplies without pre-regulation. |
| Switching Frequency | 1.5MHz (fixed) - enables use of small, low-profile inductors (e.g., 3.3µH–6.8µH) and ceramic output capacitors while avoiding AM radio band interference. |
| Output Current Limit | Programmable 0.4A to 1.2A via ILIM pin resistor - replaces discrete current-limit circuits and allows precise thermal management of downstream components. |
| Feedback Voltage | 800mV (±2%) - sets regulated output voltage using external resistor divider; enables custom VOUT or supports fixed 3.3V/5V versions (LT3663IDCB-3.3/LT3663IDCB-5). |
| Switch VCE(SAT) | 275mV at 1A - reduces conduction loss and improves efficiency at high load currents compared to MOSFET-based alternatives with higher RDS(on). |
| Thermal Resistance θJA | 64°C/W (DFN package with exposed pad soldered to PCB ground plane) - requires minimal copper area for thermal management in space-constrained designs. |
| Shutdown Current | ≤2µA - enables ultra-low-power standby in battery-backed or energy-sensitive applications without external enable logic. |
Pinout & Package
LT3663IDCB is housed in an 8-lead (2mm × 3mm) plastic DFN package with exposed thermal pad (Pin 9, GND). The exposed pad must be soldered to a PCB ground plane with thermal vias for optimal thermal performance and electrical stability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main power input | Supplies internal regulator and switch; bypass with ≥1µF ceramic capacitor close to pin to suppress high-frequency switching noise. |
| RUN | Enable/shutdown control | Logic-high (≥2.5V) enables regulation; grounded disables switching and reduces supply current to ≤2µA. |
| FB | Feedback reference node | Regulated to 0.8V; connects to resistor divider tap for adjustable output or internal divider in fixed-output variants. |
| ILIM | Current limit programming | Resistor-to-GND sets average output current limit (0.4A–1.2A); determines max power dissipation in inductor/diode. |
| SW | Switch node | Drives external inductor and catch diode; carries high di/dt pulsed current - requires short, wide trace and tight layout with input/output caps. |
| BOOST | Switch gate drive booster | Internally connected to cathode of boost diode; requires 0.1µF capacitor to SW for efficient NPN saturation above VIN. |
| ISENSE | Current sense input | Anode of internal boost diode; connects to positive terminal of external current-sense resistor (RSENSE2) for output current limiting. |
| VOUT | Output return path | Negative terminal of internal current-sense resistor; ties to output capacitor negative and load return - forms Kelvin sense path for accurate current limiting. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost diode | Eliminates external Schottky diode for BOOST capacitor charging, reducing BOM count and PCB footprint in 3.3V/5V applications. |
| Programmable output current limit | Enables system-level power budgeting by capping average inductor current - protects against overload without sacrificing transient response. |
| Internal compensation | Removes need for external compensation network, simplifying design and improving consistency across production units and temperature ranges. |
| Overvoltage lockout (39V) | Prevents switching during input surges (e.g., load dump in automotive), protecting downstream components even when VIN exceeds 36V. |
| Thermally enhanced DFN | Exposed pad (Pin 9) tied to GND provides 64°C/W junction-to-ambient thermal resistance - supports 1.2A continuous output in compact layouts. |
Applications
| Automotive Battery Regulation | Industrial 24V Supply Regulation |
|---|---|
Use Scenario: Regulating raw 12V/24V vehicle battery (with ±25% variation and 60V load-dump transients) to stable 5V for infotainment microcontrollers and CAN transceivers. IC Role / Device Role / Timing Role: Primary buck converter providing isolated, current-limited 5V rail with OVP/UVLO protection and thermal shutdown. Use Value: Eliminates need for external TVS and discrete current-limit circuitry; 60V transient tolerance avoids pre-regulator stage. | Use Scenario: Converting unregulated 24V factory-floor supply (subject to brownouts and surges) to 3.3V for PLC I/O modules and sensor signal conditioning. IC Role / Device Role / Timing Role: Fixed-frequency current-mode buck regulator delivering 1.2A with programmable current limit to manage heat in enclosed enclosures. Use Value: Programmable ILIM allows derating for ambient >85°C; internal compensation ensures stable loop response across temperature and line variations. |
| Wall Transformer Regulation | Distributed Power Architecture |
Use Scenario: Stepping down noisy 12V/15V AC-DC wall adapter output to clean 3.3V for USB peripherals and embedded Wi-Fi modules. IC Role / Device Role / Timing Role: High-efficiency, low-noise buck converter operating at 1.5MHz to minimize EMI and enable small passive components. Use Value: 1.5MHz switching allows <10µH inductors and 22µF ceramic output caps - reduces solution size by >40% vs. 500kHz alternatives. | Use Scenario: Local point-of-load regulation in multi-rail systems (e.g., FPGA carrier boards), where each subsystem requires independent 5V/3.3V with controlled inrush. IC Role / Device Role / Timing Role: Standalone current-limited buck regulator per rail, enabling independent current limiting and thermal management. Use Value: ILIM pin allows per-rail current capping (e.g., 0.6A for USB, 1.2A for core logic), preventing single-point failure from overloading shared supply. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3663IMS8E-5#TRPBF | Same IC die, but in 8-lead MSOP package (θJA = 35°C/W); identical electrical specs and pinout except VOUTS pin replaces FB on MSOP variant. | Preferred for prototyping or lower-volume designs where hand-soldering or thermal test access is needed; MSOP offers easier rework than DFN. | Select when board-level thermal testing or manual assembly is required; avoid if board space is constrained (<2mm × 3mm footprint unavailable). |
| LTC3631EMSE-5#PBF | Monolithic 5V buck with 1.2A rating, 3.1V–40V input, but no programmable current limit; uses MOSFET switch (lower quiescent current, no BOOST pin). | Better suited for low-IQ applications (25µA shutdown) but lacks output current limiting - requires external sensing for power budgeting. | Choose when ultra-low standby power is critical and current limiting is handled elsewhere; not a functional substitute for ILIM-based thermal control. |
Compared with LT3663IMS8E-5#TRPBF, the LT3663IDCB offers superior thermal performance in high-density layouts due to its lower-profile DFN package and optimized thermal pad layout; versus LTC3631EMSE-5#PBF, the LT3663IDCB provides unique programmable current limiting essential for managing power dissipation in sealed industrial enclosures.
Availability
LT3663IDCB is available at Aetrix Electronics and suitable for automotive battery regulation, industrial 24V supply regulation, and wall transformer-powered embedded systems requiring stable component supply across extended temperature ranges (–40°C to 125°C).
Supply support for LT3663IDCB 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 acquired Linear Technology in 2017 and maintains its high-performance analog and power management product lines with rigorous qualification and long-term support.
The LT3663 family was designed specifically for rugged, high-input-voltage DC/DC conversion in automotive, industrial, and telecom infrastructure - emphasizing transient robustness, programmable current limiting, and thermally efficient packaging.
FAQ
What is the maximum input voltage the LT3663IDCB can withstand without damage?
The LT3663IDCB has an absolute maximum input voltage rating of 60V for nonrepetitive 1-second transients. Its overvoltage lockout activates at 39V (typical), disabling switching to protect downstream circuitry. Continuous operation is rated from 7.5V to 36V. This makes the LT3663IDCB suitable for automotive load-dump scenarios and industrial surge environments where input rails exceed nominal 12V or 24V levels.
Does the LT3663IDCB require an external boost diode?
No, the LT3663IDCB integrates a boost diode internally connected between the ISENSE and BOOST pins. This eliminates the need for an external Schottky diode in standard 3.3V and 5V applications, reducing BOM count and PCB area. An external diode is only recommended for 2.5V or lower outputs to ensure sufficient BOOST voltage margin, per the datasheet's Figure 4b/c guidance.
How is the output current limit programmed on the LT3663IDCB?
The LT3663IDCB output current limit is set by connecting a resistor (RILIM) from the ILIM pin to GND. Values range from 28.7kΩ (1.2A) to 140kΩ (0.4A), per Table 1 in the datasheet. The LT3663IDCB uses this resistor to generate a reference voltage that the internal amplifier compares against the average inductor current sensed across RSENSE2, enabling precise, temperature-stable current limiting without external op-amps or sense resistors.
Can the LT3663IDCB operate with a 5V fixed output without external feedback resistors?
Yes - the LT3663IDCB-5#TRPBF variant (the exact orderable part referenced in the source row) features an internal resistor divider that regulates VOUT to 5.0V ±1.5%. The standard LT3663IDCB (non-suffixed) requires external R1/R2 feedback resistors. Always verify the suffix: LT3663IDCB-5#TRPBF delivers 5V without external dividers, while bare LT3663IDCB does not.
What thermal considerations apply to the LT3663IDCB's exposed pad?
Pin 9 (exposed pad) of the LT3663IDCB is electrically GND and must be soldered to a PCB ground plane with ≥4 thermal vias (0.3mm diameter) to achieve the specified θJA of 64°C/W. Inadequate soldering or insufficient copper area increases junction temperature, potentially triggering thermal shutdown at ≤125°C junction. For 1.2A continuous loads at 85°C ambient, a minimum 200mm² copper pour is recommended.
LT3663IDCB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 7.5V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 6V
- Current - Output:
- 1.2A
- Frequency - Switching:
- 1.5MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (2x3)
LT3663IDCB FAQ
1.How can I place an order for LT3663IDCB through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3663IDCB 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 LT3663IDCB reliable?
The price and inventory of LT3663IDCB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3663IDCB is usually 5 days.
3.What payment methods are accepted for LT3663IDCB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3663IDCB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3663IDCB?
LT3663IDCB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3663IDCB 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 LT3663IDCB?
For technical support, including LT3663IDCB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3663IDCB requirements.
6.How does Aetrix verify that LT3663IDCB is sourced from the original manufacturer or authorized distributors?
All LT3663IDCB 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 LT3663IDCB meets industry standards.
7.What is the process for return or replacement of LT3663IDCB?
All LT3663IDCB units undergo pre-shipment inspection (PSI). If there is an issue with LT3663IDCB, 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 LT3663IDCB part is unused and in its original packaging.
Return procedure for LT3663IDCB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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