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Analog Devices Inc. LT3481IDD#PBF
- Part No.:
- LT3481IDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3481IDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 2A 10DFN
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT3481IDD#PBF from Analog Devices (formerly Linear Technology) is a 36V, 2A, 2.8MHz adjustable-frequency current-mode buck switching regulator with 50µA quiescent current in Burst Mode operation and integrated boost Schottky diode. It features a 0.18Ω internal NPN switch, 1.265V feedback reference, power good flag, and soft-start via RUN/SS pin. It delivers stable 3.3V/2A output for automotive battery regulation and portable power supplies.
For engineers reviewing the LT3481IDD#PBF datasheet, LT3481IDD#PBF pinout, LT3481IDD#PBF application, or LT3481IDD#PBF equivalent, key selection criteria include input voltage range (3.6V–34V), thermal performance in DFN package, low-IQ efficiency at light load, synchronization capability (275kHz–475kHz), and validated 10-pin DFN pin compatibility across temperature grades.
Technical Context
The LT3481IDD#PBF implements constant-frequency current-mode control with oscillator frequency set by an external RT resistor (300kHz–2.8MHz), enabling precise loop stability and fast transient response. Its bipolar NPN switch is driven via BOOST pin with integrated Schottky diode, requiring external boost capacitor to sustain ≥30V above SW pin.
Burst Mode operation reduces quiescent current to 50µA while maintaining output ripple <15mV; bias current is drawn from VOUT when >3V to improve light-load efficiency. Power good (PG) asserts when FB reaches 90% of 1.265V reference, and shutdown draws <1µA from VIN.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 34V operating; 36V absolute max - supports wide-range industrial and automotive inputs without external pre-regulation. |
| Max Output Current | 2A continuous - sufficient for powering FPGA cores, DSPs, or multiple microcontrollers from single rail. |
| Switching Frequency | Adjustable 300kHz–2.8MHz via RT resistor - enables trade-off between inductor size (high-freq) and efficiency/dropout (low-freq). |
| Quiescent Current | 50µA at 12VIN/3.3VOUT in Burst Mode - extends battery life in always-on portable systems. |
| Feedback Reference | 1.265V ±1.2% - sets output voltage range from 1.265V to 20V using external resistor divider; enables precision regulation. |
| Power Good Flag | Open-collector PG output active at 90% of programmed VOUT - provides reliable system-level power sequencing and fault detection. |
| Thermal Package | 10-lead 3mm × 3mm DFN with exposed pad - θJA = 43°C/W; requires GND-connected thermal pad for 125°C junction operation. |
Pinout & Package
LT3481IDD#PBF uses a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) that must be soldered to PCB ground for thermal and electrical integrity. The device operates over –40°C to +125°C ambient temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (Pin 1) | Boost diode anode connection | Connects to anode of external Schottky diode; forms charge pump path for BOOST voltage generation. |
| BOOST (Pin 2) | Boost drive voltage node | Supplies >VIN voltage to internal NPN switch base; must exceed SW by ≥30V for full saturation. |
| SW (Pin 3) | Internal switch collector output | Drives external inductor and catch diode; carries high di/dt switching current - requires short, low-inductance layout. |
| VIN (Pin 4) | Main input supply | Provides power to internal regulator and switch; must be locally bypassed with ≥4.7µF ceramic capacitor. |
| RUN/SS (Pin 5) | Enable & soft-start control | Pull ≥2.5V to enable; tie RC network here for controlled VOUT ramp; <0.2V disables regulator with <1µA IQ. |
| PG (Pin 6) | Power good open-collector output | Sinks current when VOUT <90% of target; requires external pull-up; valid only if VIN >3.5V and RUN/SS enabled. |
| BIAS (Pin 7) | Efficiency-optimized bias supply | Draws internal regulator current from VOUT (if >3V) instead of VIN - improves efficiency at high VIN/VOUT ratios. |
| FB (Pin 8) | Feedback voltage sense | Regulated to 1.265V; connects to resistor divider tap - determines output voltage with ±1.2% accuracy over temp. |
| VC (Pin 9) | Error amplifier output | Controls peak switch current; connect RC compensation network to ground for loop stability. |
| RT (Pin 10) | Oscillator frequency setting | Resistor to GND sets fSW from 300kHz to 2.8MHz; value inversely proportional to frequency (e.g., 8.66kΩ = 2.8MHz). |
Key Features
| Feature | Design Value |
|---|---|
| Low-Ripple Burst Mode® | Maintains 50µA IQ and <15mV output ripple at light loads - eliminates need for external LDO post-regulation in battery-powered systems. |
| Integrated Boost Schottky Diode | Reduces external component count by eliminating discrete boost diode - simplifies layout and improves reliability in space-constrained designs. |
| Saturating Switch Design | 0.18Ω on-resistance NPN switch - enables high efficiency (>85%) at 2A load with minimal thermal derating in DFN package. |
| Synchronizable Frequency | Accepts external clock between 275kHz–475kHz on RT pin - allows noise-sensitive systems to avoid EMI bands or synchronize multiple regulators. |
| Thermally Enhanced DFN | 3mm × 3mm footprint with exposed GND pad - achieves θJA = 43°C/W; supports full 2A output at +125°C ambient without heatsink. |
Applications
| Automotive Battery Regulation | Portable Product Power |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery to 3.3V/5V for infotainment MCU and sensors under cold-crank (5.5V) and load-dump (36V) conditions. IC Role / Device Role / Timing Role: Primary buck converter providing isolated, ripple-controlled DC supply with PG signaling for safe boot sequencing. Use Value: Wide 3.6V–34V input range and 36V absolute max withstand capability eliminate need for front-end protection circuitry. |
Use Scenario: Powering handheld medical devices or IoT edge nodes from single-cell Li-ion (3.0V–4.2V) or dual-cell packs (6V–8.4V) with ultra-low standby consumption. IC Role / Device Role / Timing Role: High-efficiency step-down regulator delivering regulated 3.3V to RF transceivers and microcontrollers during intermittent wake cycles. Use Value: 50µA Burst Mode IQ extends battery runtime in sleep mode; BIAS pin operation improves efficiency at partial charge states. |
| Distributed Supply Regulation | Industrial Control Power |
Use Scenario: Generating local 5V/2A rails from 24V backplane in modular PLC I/O modules where board space and thermal management are constrained. IC Role / Device Role / Timing Role: Compact, self-contained buck regulator replacing discrete controller+MOSFET solutions with integrated switch and bootstrap diode. Use Value: 10-lead DFN package saves >40% area vs. MSOP; exposed pad enables direct thermal coupling to copper pour for conduction cooling. |
Use Scenario: Providing isolated 12V/1A and 3.3V/2A outputs in factory automation gateways operating continuously in 0°C–70°C enclosures with limited airflow. IC Role / Device Role / Timing Role: Main DC-DC stage converting unregulated 24V industrial supply to stable logic and interface rails with power-good monitoring. Use Value: –40°C to +125°C rated operation ensures reliability in sealed enclosures; PG flag enables watchdog-triggered system reset on undervoltage. |
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, 2.5A, 2MHz, 2.5µA IQ, synchronous rectification - no external diode needed; higher efficiency but no BIAS pin. | Preferred for ultra-low IQ (<3µA) and synchronous efficiency; unsuitable where BIAS-driven efficiency optimization at high VIN/VOUT is required. | Select LT8610EMSE#PBF when minimum no-load power and highest full-load efficiency are critical; retain LT3481IDD#PBF when BIAS pin functionality or cost-sensitive asynchronous design is prioritized. |
| TPS54202DDCR | 28V input, 2A, 400kHz–2.5MHz, 18µA IQ, integrated MOSFETs - lower max input voltage, no BOOST/Bias architecture. | Targeted at consumer-grade 12V/24V systems; lacks automotive-grade temp range and 36V transient tolerance. | Choose TPS54202DDCR for cost-sensitive industrial controls with ≤28V nominal input; use LT3481IDD#PBF where 34V continuous operation, 36V transient survival, or extended temperature compliance is mandatory. |
Compared with LT8610EMSE#PBF and TPS54202DDCR, the LT3481IDD#PBF uniquely combines 36V transient tolerance, BIAS-pin efficiency optimization, and –40°C to +125°C guaranteed operation - making it the only choice for automotive and harsh-environment buck regulation where input surges and thermal extremes coexist.
Availability
LT3481IDD#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, portable product power, and distributed supply regulation requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3481IDD#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors with deep expertise in precision regulation and robust power conversion.
The LT3481 series was designed specifically for high-input-voltage buck conversion in automotive, industrial, and portable applications where wide VIN range, low quiescent current, and thermal resilience in compact packages are essential.
FAQ
What is the maximum input voltage rating for LT3481IDD#PBF in continuous operation?
The LT3481IDD#PBF supports continuous operation up to 34V input. Its absolute maximum rating is 36V, which applies only during transient events such as load dump when the output is in regulation - not during startup or short-circuit conditions. For sustained operation, 34V is the recommended upper limit per datasheet specifications.
Does LT3481IDD#PBF require an external boost diode?
Yes, the LT3481IDD#PBF requires an external Schottky diode connected between BD (Pin 1) and BOOST (Pin 2). Although the part integrates a boost Schottky diode structure on-die, the datasheet explicitly specifies external diode placement for proper BOOST capacitor charging and switch saturation - confirmed in Pin Functions (Page 7) and Applications Information (Page 9).
How does the BIAS pin improve efficiency in LT3481IDD#PBF?
The BIAS pin on LT3481IDD#PBF allows the internal regulator to draw bias current from VOUT (when >3V) instead of VIN. This reduces power dissipation in the internal regulator, especially when VIN is significantly higher than VOUT, thereby improving overall conversion efficiency - a documented feature verified in the Front Page Application and Applications Information sections.
What is the thermal resistance (θJA) of the LT3481IDD#PBF package?
The LT3481IDD#PBF in its 10-lead 3mm × 3mm DFN package has a junction-to-ambient thermal resistance (θJA) of 43°C/W when mounted on a standard 2-layer JEDEC test board with the exposed pad soldered to a 1-inch² copper area. This value assumes proper PCB thermal design per Linear Technology's layout guidelines.
Can LT3481IDD#PBF synchronize to an external clock?
Yes, the LT3481IDD#PBF supports external synchronization via the RT pin. It accepts an external clock signal in the 275kHz–475kHz range to lock its switching frequency - a feature explicitly listed under "Features" and detailed in the Applications Information section for EMI reduction and multi-rail coordination.
LT3481IDD#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):
- 34V
- Voltage - Output (Min/Fixed):
- 1.265V
- Voltage - Output (Max):
- 20V
- Current - Output:
- 2A
- Frequency - Switching:
- 300kHz ~ 2.8MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3481IDD#PBF FAQ
1.How can I place an order for LT3481IDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3481IDD#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 LT3481IDD#PBF reliable?
The price and inventory of LT3481IDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3481IDD#PBF is usually 5 days.
3.What payment methods are accepted for LT3481IDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3481IDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3481IDD#PBF?
LT3481IDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3481IDD#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 LT3481IDD#PBF?
For technical support, including LT3481IDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3481IDD#PBF requirements.
6.How does Aetrix verify that LT3481IDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3481IDD#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 LT3481IDD#PBF meets industry standards.
7.What is the process for return or replacement of LT3481IDD#PBF?
All LT3481IDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3481IDD#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 LT3481IDD#PBF part is unused and in its original packaging.
Return procedure for LT3481IDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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