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Analog Devices Inc. LT3481HDD#PBF
- Part No.:
- LT3481HDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3481HDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 2A 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,431
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Product details
Overview
LT3481HDD#PBF from Analog Devices (formerly Linear Technology) is a 36V, 2A, 2.8MHz monolithic step-down switching regulator with current-mode control, integrated 0.18Ω bipolar NPN switch and on-chip boost Schottky diode driver. It delivers regulated 1.265V–20V output in automotive battery regulation and industrial power supplies where input ranges from 3.6V to 34V are required.
For engineers reviewing the LT3481HDD#PBF datasheet, LT3481HDD#PBF pinout, LT3481HDD#PBF application, or LT3481HDD#PBF equivalent, key selection criteria include its –40°C to 150°C junction-rated thermal performance, 50µA quiescent current in Burst Mode, 1.265V feedback reference, and 300kHz–2.8MHz adjustable switching frequency with RT-resistor programming.
Technical Context
The LT3481HDD#PBF employs constant-frequency current-mode PWM control with an internal 1.265V reference and error amplifier driving the VC pin to regulate peak switch current. Its oscillator supports programmable frequency (300kHz–2.8MHz) via external RT resistor and includes frequency foldback during startup or overload.
It integrates a bipolar NPN power switch with 0.18Ω on-resistance, uses BOOST/SW/BD pins to drive an external Schottky diode for high-side bootstrapping, and features a BIAS pin that draws bias current from VOUT ≥3V to improve light-load efficiency. Power Good (PG) signals at 90% of programmed VOUT with open-collector output.
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 including cold-crank transients. |
| Output Current | 2A continuous - sufficient for powering FPGA I/O banks, microcontroller cores, or sensor subsystems. |
| Switching Frequency | 300kHz to 2.8MHz (RT-programmable) - enables trade-off between small magnetics (high-f) and high VIN/VOUT ratio support (low-f). |
| Quiescent Current | 50µA at 12VIN→3.3VOUT in Burst Mode - extends battery life in portable or always-on monitoring systems. |
| Feedback Reference | 1.265V ±15mV - sets precise output voltage via external resistor divider; line regulation <0.02%/V ensures stability across input range. |
| Thermal Rating | –40°C to +150°C junction temperature - qualified for under-hood automotive and high-ambient industrial environments. |
| Shutdown Current | <1µA - enables ultra-low-power system-level sleep modes without auxiliary LDOs. |
Pinout & Package
LT3481HDD#PBF is housed in a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11), which must be soldered to PCB ground for optimal thermal resistance (θJA = 43°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (Pin 1) | Boost Diode Anode Connection | Connects to anode of external Schottky diode; forms bootstrap path for high-side switch drive. |
| BOOST (Pin 2) | Bootstrap Voltage Supply | Provides >VIN voltage to drive internal NPN switch base; rated to 56V with 30V max above SW. |
| SW (Pin 3) | Switch Node | Drives external inductor and catch diode; carries full switching current and high dv/dt. |
| VIN (Pin 4) | Main Input Supply | Supplies internal regulator and switch; requires local 4.7µF ceramic bypass; max 36V. |
| RUN/SS (Pin 5) | Enable & Soft-Start Control | Logic-high ≥2.5V enables operation; RC network here controls output voltage ramp rate. |
| PG (Pin 6) | Power Good Flag | Open-collector output asserts high when VOUT reaches 90% of regulation; valid only if VIN > 3.5V and RUN/SS high. |
| BIAS (Pin 7) | Bias Supply Input | Accepts external ≥3V supply (typically VOUT); reduces quiescent current by shifting bias source away from VIN. |
| FB (Pin 8) | Feedback Input | Regulated to 1.265V; connects to resistor divider tap; bias current ≤100nA minimizes divider error. |
| VC (Pin 9) | Error Amplifier Output | Controls peak switch current; external RC compensation network stabilizes loop dynamics. |
| RT (Pin 10) | Oscillator Frequency Set | Resistor to ground programs switching frequency from 300kHz to 2.8MHz per datasheet table. |
Key Features
| Feature | Design Value |
|---|---|
| Low-Ripple Burst Mode® | Maintains output ripple <15mV while achieving 50µA IQ - eliminates need for secondary LDO in low-power standby paths. |
| Integrated Boost Diode Driver | Eliminates need for external gate driver IC; supports standard Schottky diodes (e.g., Diodes Inc. PDS360) with <2µA reverse leakage. |
| Saturating Switch Design | 0.18Ω on-resistance at 2A ensures <360mV conduction loss - improves full-load efficiency over MOSFET-based alternatives at same current. |
| Power Good Flag | Open-collector PG output with 100–600µA sink capability - directly interfaces with µC reset inputs or system sequencers without level-shifting. |
| Soft-Start Capability | Controlled voltage ramp on RUN/SS pin prevents inrush current and output overshoot - no external circuitry required beyond R/C. |
Applications
| Automotive Battery Regulation | Industrial Distributed Power |
|---|---|
|
Use Scenario: Regulating 12V/24V vehicle battery rails to 3.3V/5V for ADAS camera modules and CAN transceivers under cold-crank (4.5V) and load-dump (36V) conditions. IC Role / Device Role / Timing Role: Primary buck converter providing isolated, stable DC output with fast transient response to engine cranking events. Use Value: –40°C to 150°C rating ensures operation in engine compartment; 36V abs max withstands load-dump spikes without clamping circuits. |
Use Scenario: Local point-of-load conversion in PLC backplanes or motor drives where 24V or 48V bus supplies 5V logic and 3.3V FPGA I/O rails. IC Role / Device Role / Timing Role: High-efficiency, thermally robust DC-DC stage delivering up to 2A with minimal heatsinking. Use Value: 50µA Burst Mode IQ extends uptime in unpowered standby; adjustable frequency avoids EMI-sensitive bands in dense control cabinets. |
| Portable Product Power | Wall Transformer Regulation |
|
Use Scenario: Powering handheld test equipment with Li-ion battery input (3.0–4.2V) and dual-output requirements (3.3V MCU + 1.8V sensor rail). IC Role / Device Role / Timing Role: Main step-down regulator accepting wide VIN range and enabling BIAS-pin efficiency boost when VOUT ≥3V. Use Value: 3.6V min VIN allows operation down to near-dead battery; BIAS connection reduces IQ by >50% vs VIN-only biasing. |
Use Scenario: Replacing linear regulators in AC/DC wall adapters supplying 5V/2A to USB-C PD accessories or IoT gateways. IC Role / Device Role / Timing Role: High-efficiency switching alternative to 78xx series, reducing thermal stress and adapter size. Use Value: 2.8MHz max frequency permits use of 1µH inductors - cuts solution footprint by >40% vs 500kHz designs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#PBF | 40V input, 1.5A, 3mm × 4mm MSOP, 3.5µA IQ - lower current, lower quiescent, no integrated boost diode driver. | Preferred for ultra-low-IQ battery-powered sensors; requires external bootstrap diode and capacitor. | Select when IQ <10µA is mandatory and output current ≤1.5A; avoid if high-voltage transient immunity or integrated boost drive is needed. |
| MP2451DT-LF-Z | 36V input, 2A, 8-pin SOIC, 2.2MHz fixed freq, 100µA IQ - no BIAS pin, no PG flag, no soft-start control. | Suitable for cost-sensitive industrial SMPS where feature count is secondary to BOM simplicity. | Select for basic 2A buck needs with fixed frequency; avoid when automotive temp grade, PG signaling, or programmable soft-start is required. |
Compared with LTC3631EMSE#PBF and MP2451DT-LF-Z, the LT3481HDD#PBF uniquely combines 150°C operation, integrated boost diode drive, and 50µA Burst Mode IQ - making it the only option qualified for under-hood automotive buck conversion with minimal external components.
Availability
LT3481HDD#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 voltage ranges.
Supply support for LT3481HDD#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 acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for all Linear power products, including rigorous AEC-Q100 stress testing for automotive-grade variants.
The LT3481 product line was designed specifically for high-input-voltage, high-temperature DC-DC conversion in automotive, industrial, and avionics systems - emphasizing robustness, integrated functionality, and minimal external component count.
FAQ
What is the maximum allowable input voltage for LT3481HDD#PBF in continuous regulation mode?
The LT3481HDD#PBF supports input transients up to 36V when operating in regulation with no short-circuit or startup events. In normal steady-state operation, it accepts 3.6V to 34V continuously. The 36V absolute maximum rating applies only during pulse-skipping mode under transient conditions - sustained operation above 34V risks exceeding thermal limits or violating safe operating area constraints.
How does the BIAS pin improve efficiency in LT3481HDD#PBF?
The BIAS pin on the LT3481HDD#PBF allows the IC to draw bias current from VOUT (if ≥3V) instead of VIN, reducing input supply current significantly at light loads. When VOUT is 5V or higher, this architecture lowers quiescent current by up to 50% compared to VIN-only biasing - directly extending battery runtime in portable applications powered by the LT3481HDD#PBF.
Can LT3481HDD#PBF synchronize to an external clock?
No, the LT3481HDD#PBF does not support external clock synchronization. Its oscillator is RT-resistor programmable from 300kHz to 2.8MHz but lacks a SYNC pin or digital interface for master clock alignment. For synchronized multi-rail designs, designers must use free-running frequencies or select alternatives like the LTC3891, which includes full synchronization capability.
What is the purpose of the exposed pad on the LT3481HDD#PBF DFN package?
The exposed pad (Pin 11) on the LT3481HDD#PBF is electrically and thermally connected to GND. It must be soldered to a PCB copper pour tied to system ground to achieve the specified θJA of 43°C/W. Omitting this connection degrades thermal performance by >25°C/W and risks thermal shutdown under 2A load at elevated ambient temperatures.
Does LT3481HDD#PBF require an external Schottky diode?
Yes, the LT3481HDD#PBF requires an external Schottky diode connected between BD (Pin 1) and SW (Pin 3). While it integrates the boost diode driver circuitry and switch, the diode itself is external - typical selections include Diodes Inc. PDS360 or ON Semiconductor MBRM120E, chosen for low VF (<550mV @ 2A) and low reverse leakage (<2µA @ 10V).
LT3481HDD#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3481HDD#PBF FAQ
1.How can I place an order for LT3481HDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3481HDD#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 LT3481HDD#PBF reliable?
The price and inventory of LT3481HDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3481HDD#PBF is usually 5 days.
3.What payment methods are accepted for LT3481HDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3481HDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3481HDD#PBF?
LT3481HDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3481HDD#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 LT3481HDD#PBF?
For technical support, including LT3481HDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3481HDD#PBF requirements.
6.How does Aetrix verify that LT3481HDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3481HDD#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 LT3481HDD#PBF meets industry standards.
7.What is the process for return or replacement of LT3481HDD#PBF?
All LT3481HDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3481HDD#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 LT3481HDD#PBF part is unused and in its original packaging.
Return procedure for LT3481HDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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