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Analog Devices Inc. LT3972IDD#PBF
- Part No.:
- LT3972IDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3972IDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 3.5A 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:135
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Product details
Overview
LT3972IDD#PBF from Analog Devices (formerly Linear Technology) is a monolithic current-mode step-down switching regulator IC designed for wide-input automotive and industrial power conversion. It operates from 3.6V to 33V input, delivers up to 3.5A output current, features 75μA quiescent current in Burst Mode®, supports adjustable switching frequency from 200kHz to 2.4MHz, and integrates a 95mΩ NPN switch with on-chip boost Schottky diode driver - used in 5V/3.5A distributed supply regulation.
For engineers reviewing the LT3972IDD#PBF datasheet, LT3972IDD#PBF pinout, LT3972IDD#PBF application, or LT3972IDD#PBF equivalent, key selection considerations include its 33V max operating input (62V transient tolerant), thermal shutdown protection, power good flag (PG), soft-start via RUN/SS pin, and compatibility with 3mm × 3mm DFN-10 package with exposed pad for low θJA = 45°C/W.
Technical Context
The LT3972IDD#PBF implements constant-frequency current-mode control with internal oscillator set by RT pin resistor, enabling fast transient response and stable loop behavior across wide duty cycles. Its bipolar NPN switch is driven via integrated BOOST circuitry, requiring external boost capacitor and Schottky diode to generate gate drive voltage above VIN.
Burst Mode® operation reduces no-load input current to 75μA while maintaining <15mVP-P output ripple; bias current can be drawn from VOUT when >3V to further improve light-load efficiency. Overvoltage lockout activates at 33V (typ), disabling switching while sustaining 62V transients.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 33V continuous; withstands 62V non-repetitive transients - enables direct connection to 24V/36V automotive or industrial rails. |
| Max Output Current | 3.5A DC - supports high-current point-of-load conversion without external MOSFETs. |
| Quiescent Current | 75μA at 12VIN → 3.3VOUT in Burst Mode® - extends battery life in always-on systems. |
| Switch RDS(on) | 95mΩ typical - minimizes conduction loss at full load; supports >90% efficiency at 12V→5V/3A. |
| Switching Frequency | 200kHz to 2.4MHz (RT-programmable) - allows trade-off between small magnetics (high fSW) and high-VIN capability (low fSW). |
| Feedback Voltage | 0.790V ±10mV - sets precise output regulation; enables adjustable VOUT from 0.79V to 30V using resistor divider. |
| Power Good Flag | Open-collector PG asserts when VOUT reaches 91% of target - provides reliable system power sequencing signal. |
| Thermal Protection | Internal junction temperature shutdown - prevents damage during overload or poor PCB heatsinking. |
Pinout & Package
LT3972IDD#PBF is housed in a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) soldered to PCB ground for optimal thermal performance (θJA = 45°C/W, θJC = 10°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (Pin 1) | Boost Diode Anode Connection | Connects to Schottky diode anode; supplies bias current to internal regulator - enables efficient high-side drive. |
| BOOST (Pin 2) | Boost Capacitor Drive Node | Provides elevated voltage (>VIN) to saturate internal NPN switch - requires external boost cap and diode. |
| SW (Pin 3) | Switch Node | Output of internal power switch - connects directly to inductor, catch diode cathode, and boost capacitor. |
| VIN (Pin 4) | Main Input Supply | Supplies power to internal regulator and switch - must be locally bypassed with ≥10μF ceramic capacitor. |
| RUN/SS (Pin 5) | Enable & Soft-Start Control | Logic-level enable (≥2.5V = ON); RC ramp generates controlled VOUT rise - prevents inrush current. |
| SYNC (Pin 6) | External Clock Input | Accepts 250kHz–2MHz clock for synchronization - eliminates beat frequencies in multi-regulator systems. |
| PG (Pin 7) | Power Good Output | Open-collector flag signaling VOUT ≥91% of regulation - requires external pull-up for MCU reset or sequencing logic. |
| FB (Pin 8) | Feedback Input | Sense node regulated to 0.790V - determines output voltage via resistor divider (R1/R2). |
| VC (Pin 9) | Error Amplifier Output | Controls peak switch current; RC compensation network here stabilizes control loop. |
| RT (Pin 10) | Oscillator Frequency Set | Resistor-to-ground sets switching frequency (200kHz–2.4MHz) - enables optimization for size vs. efficiency. |
| Exposed Pad (Pin 11) | Thermal Ground | Must be soldered to PCB GND plane - primary path for heat dissipation; critical for thermal reliability. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Boost Diode Driver | Eliminates need for external high-voltage bootstrap circuit - simplifies layout and reduces BOM count. |
| Low-Ripple Burst Mode® | Maintains <15mVP-P output ripple at light loads while drawing only 75μA - meets stringent noise requirements in sensor and RF subsystems. |
| Output Voltage Programmability | 0.79V to 30V via two-resistor feedback divider - supports diverse rail requirements (e.g., 1.2V FPGA core, 12V analog, 24V actuator). |
| Synchronizable Switching | Accepts external clock from 250kHz to 2MHz - enables EMI reduction and deterministic timing in synchronized power domains. |
| Overvoltage Lockout (OVL) | Disables switching at 33V (min) input - protects downstream circuitry during load dump or hot-swap events in automotive applications. |
| Thermally Enhanced DFN | 3mm × 3mm footprint with exposed pad - delivers 45°C/W junction-to-ambient thermal resistance for compact, high-power-density designs. |
Applications
| Automotive Battery Regulation | Distributed Supply Regulation |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery to stable 5V or 3.3V for infotainment head unit microcontrollers and CAN transceivers under cold-crank (4.5V) and load-dump (62V) conditions. IC Role / Device Role / Timing Role: Primary buck controller providing isolated, regulated DC-DC conversion with OVL, PG flag, and thermal protection. Use Value: Enables single-chip solution meeting AEC-Q100 Grade I (−40°C to 125°C) requirements without external FETs or complex protection circuitry. | Use Scenario: Generating local 3.3V/3.5A rails from a 12V backplane in industrial PLC I/O modules where space and thermal management are constrained. IC Role / Device Role / Timing Role: High-efficiency point-of-load regulator with programmable frequency to avoid sensitive 1–10MHz EMI bands. Use Value: Delivers full 3.5A output in 9mm² DFN package with <15mV ripple - eliminates need for secondary LDO post-regulation. |
| Industrial Supplies | Wall Transformer Regulation |
Use Scenario: Replacing linear regulators in factory automation sensors powered from unregulated 24V DC supplies subject to brownouts and surges. IC Role / Device Role / Timing Role: Wide-input buck converter with 3.6V start-up and 62V surge tolerance - ensures uninterrupted operation during line disturbances. Use Value: 75μA quiescent current extends battery backup runtime; soft-start prevents tripping upstream fuses during cold start. | Use Scenario: Converting rectified AC wall adapter output (e.g., 36V DC) to regulated 5V/3A for USB-C PD accessories or smart home hubs. IC Role / Device Role / Timing Role: High-input buck controller with integrated boost driver - replaces discrete transformer-isolated flyback in cost-sensitive consumer applications. Use Value: Eliminates optocoupler, TL431, and external MOSFET - reduces bill-of-materials and improves long-term reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5164QDDARQ1 | 4.5V–65V input, 3.5A, 1.5MHz fixed freq, no integrated boost diode driver - requires external bootstrap diode/cap. | Designed for automotive AEC-Q100 Grade 1; includes spread-spectrum EMI reduction - better for strict automotive EMC compliance. | Choose LM5164QDDARQ1 if 65V absolute max input or AEC-Q100 certification is mandatory; accept added external components. |
| MPQ4433AGL-Z | 4V–36V input, 3.5A, 2.2MHz max, integrated MOSFETs (no external diode needed), but no boost driver - uses synchronous rectification. | Lower IQ (25μA) and smaller solution size; lacks PG flag and OVL - suited for space-constrained consumer electronics, not safety-critical systems. | Choose MPQ4433AGL-Z for ultra-low-noise, compact designs where PG and 62V transient tolerance are not required. |
Compared with LM5164QDDARQ1 and MPQ4433AGL-Z, the LT3972IDD#PBF uniquely combines 62V transient survivability, integrated boost diode driver, and 75μA Burst Mode® IQ in a 3mm × 3mm DFN - making it optimal for ruggedized industrial and legacy automotive platforms needing minimal external components.
Availability
LT3972IDD#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, distributed supply regulation, and industrial power supplies requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LT3972IDD#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.
The LT3972IDD#PBF belongs to Linear's high-voltage monolithic buck regulator product line, engineered specifically for robust, wide-input industrial and automotive power conversion where reliability under voltage transients and low quiescent current are critical design requirements.
FAQ
What is the maximum input voltage rating for LT3972IDD#PBF during continuous operation?
The LT3972IDD#PBF is rated for continuous operation up to 33V input. Its absolute maximum rating is 62V for non-repetitive 1-minute transients. When VIN exceeds 33V (minimum OVL threshold), the device disables switching to protect itself and downstream circuitry while sustaining the overvoltage condition safely - a key feature for automotive load-dump immunity.
Does LT3972IDD#PBF require an external Schottky diode, and why?
Yes, the LT3972IDD#PBF requires an external Schottky diode connected between BD (Pin 1) and SW (Pin 3). The IC integrates a boost diode *driver*, not the diode itself. This external diode forms the boost circuit that generates the elevated voltage needed to fully saturate the internal bipolar NPN switch - essential for achieving low conduction losses and high efficiency across the full input range.
How does the LT3972IDD#PBF achieve 75μA quiescent current, and under what conditions?
The LT3972IDD#PBF achieves 75μA quiescent current in Burst Mode® operation at light loads (e.g., 12VIN → 3.3VOUT). In this mode, the controller shuts down most internal circuitry between switching bursts, minimizing idle power draw. Additionally, when VOUT > 3V, the IC draws bias current from the output rail instead of VIN - further reducing input supply current and improving system-level efficiency.
Can LT3972IDD#PBF synchronize to an external clock, and what is its supported frequency range?
Yes, the LT3972IDD#PBF supports external clock synchronization via the SYNC pin (Pin 6). It accepts TTL/CMOS-compatible clock signals from 250kHz to 2MHz - enabling precise timing alignment in multi-rail power systems to suppress beat frequencies and simplify EMI filtering. If unused, SYNC must be tied to GND to ensure proper Burst Mode® operation.
What thermal management considerations apply to the LT3972IDD#PBF in the DFN-10 package?
The LT3972IDD#PBF in the 3mm × 3mm DFN package relies critically on soldering the exposed pad (Pin 11) to a large PCB copper area connected to system ground. With θJA = 45°C/W and θJC = 10°C/W, inadequate pad thermal connection will cause rapid junction temperature rise under 3.5A load. Designers must use ≥4 thermal vias under the pad and connect to inner-layer ground planes to maintain TJ ≤125°C in ambient temperatures up to 85°C.
LT3972IDD#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):
- 33V
- 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-DFN (3x3)
LT3972IDD#PBF FAQ
1.How can I place an order for LT3972IDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3972IDD#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 LT3972IDD#PBF reliable?
The price and inventory of LT3972IDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3972IDD#PBF is usually 5 days.
3.What payment methods are accepted for LT3972IDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3972IDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3972IDD#PBF?
LT3972IDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3972IDD#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 LT3972IDD#PBF?
For technical support, including LT3972IDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3972IDD#PBF requirements.
6.How does Aetrix verify that LT3972IDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3972IDD#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 LT3972IDD#PBF meets industry standards.
7.What is the process for return or replacement of LT3972IDD#PBF?
All LT3972IDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3972IDD#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 LT3972IDD#PBF part is unused and in its original packaging.
Return procedure for LT3972IDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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