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Analog Devices Inc. LT3972IDD#TRPBF
- Part No.:
- LT3972IDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3972IDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 3.5A 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,755
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Product details
Overview
LT3972IDD#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic current-mode step-down switching regulator with integrated 95mΩ NPN switch and boost Schottky diode, supporting 3.6V–33V input, 0.79V–30V adjustable output, 3.5A max load, 200kHz–2.4MHz programmable frequency, and 75μA quiescent current in Burst Mode. It delivers stable 5V/3.5A power for automotive battery regulation and industrial distributed supplies.
For engineers reviewing the LT3972IDD#TRPBF datasheet, LT3972IDD#TRPBF pinout, LT3972IDD#TRPBF application, or LT3972IDD#TRPBF equivalent, key selection criteria include its 62V transient tolerance, thermal shutdown, power good flag, soft-start via RUN/SS, and compatibility with 3mm × 3mm DFN-10 packaging for high-density PCB layouts.
Technical Context
The LT3972IDD#TRPBF implements constant-frequency current-mode control with an internal error amplifier (gm = 500 μmho), slope compensation, and active VC clamp for precise peak-current limiting. Its oscillator supports resistor-programmed frequency (RT pin) and external synchronization (SYNC pin, 250kHz–2MHz range).
Operation includes low-ripple Burst Mode for light-load efficiency, frequency foldback during startup/overload, bias sourcing from BD pin when VOUT > 3V, and overvoltage lockout at 33V (min) to protect downstream circuitry during 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 without pre-regulation. |
| Output Current | Up to 3.5A DC - supports high-power microcontrollers, FPGAs, and sensor modules without external pass devices. |
| Quiescent Current | 75μA at 12VIN → 3.3VOUT in Burst Mode - extends battery life in always-on telematics and remote monitoring systems. |
| Switching Frequency | 200kHz to 2.4MHz, resistor-programmable via RT pin - allows optimization of inductor size (e.g., 4.7μH at 600kHz) vs. efficiency trade-offs. |
| Feedback Reference | 0.790V ±10mV (–40°C to 125°C) - enables accurate, temperature-stable output regulation across wide ambient conditions. |
| Power Good Threshold | 91% of programmed VOUT with 65mV offset and 10mV hysteresis - provides reliable system reset signaling without external comparators. |
| Thermal Protection | Internal junction shutdown above 150°C (H-grade) - ensures safe operation under sustained overload or poor heatsinking. |
| Shutdown Current | <1μA - meets ultra-low-power requirements for energy-harvesting and battery-backed applications. |
Pinout & Package
LT3972IDD#TRPBF is housed in a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) soldered to PCB ground for low θJA = 45°C/W. Pin numbering follows standard top-view layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (1) | Boost Diode Anode Input | Connects to Schottky diode anode; supplies bias current to internal regulator - enables efficiency boost when VOUT > 3V. |
| BOOST (2) | Bootstrap Drive Voltage | Provides >VIN voltage to saturate internal NPN switch - requires external capacitor/diode network for full-switch conduction. |
| SW (3) | Switch Node Output | Drives inductor, catch diode cathode, and boost capacitor - high dV/dt node requiring tight layout and ground plane coupling. |
| VIN (4) | Main Power Input | Supplies internal regulator and switch driver; must be locally bypassed with ≥10μF X7R ceramic - supports up to 62V transients. |
| RUN/SS (5) | Enable & Soft-Start Control | Logic-level enable (≥2.5V = on); RC ramp generates controlled VOUT rise - prevents inrush current and stabilizes startup. |
| SYNC (6) | External Clock Input | Accepts TTL/CMOS clock (250kHz–2MHz); grounds for Burst Mode - eliminates beat frequencies in multi-rail systems. |
| PG (7) | Open-Collector Power Good | Sinks current when VFB reaches 91% of target - pulls high via external resistor to signal valid regulation to MCU or PMIC. |
| FB (8) | Feedback Input | Regulated to 0.790V; connects to resistor divider from VOUT - sets output voltage with ±1.3% accuracy over temp and line. |
| VC (9) | Error Amplifier Output | Controls peak switch current; RC compensation network here stabilizes loop - critical for transient response and phase margin. |
| RT (10) | Oscillator Frequency Set | Resistor-to-ground sets fSW (200kHz–2.4MHz); e.g., 63.4kΩ = 600kHz - enables EMI tuning and component size optimization. |
| Exposed Pad (11) | Thermal & Electrical Ground | Mandatory PCB solder connection - reduces thermal resistance and improves EMI performance by lowering ground impedance. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Boost Schottky Diode | Eliminates external diode, reducing BOM count and board area while maintaining <15mVP-P ripple in Burst Mode. |
| Low-Ripple Burst Mode Operation | Maintains 75μA IQ and <15mVP-P output ripple at light loads - avoids audible noise and preserves signal integrity in sensitive analog sections. |
| Saturating NPN Switch (95mΩ) | Enables high-efficiency operation at high duty cycles (e.g., 5V out from 12V in) without MOSFET gate drive complexity. |
| Programmable Switching Frequency | 200kHz–2.4MHz range via single RT resistor - supports EMI compliance (e.g., >2MHz for CISPR-25 Class 5) and compact magnetics. |
| Overvoltage Lockout (33V min) | Disables switching during >33V input events - protects internal circuitry and enables use with 42V automotive transients (ISO 7637-2 Pulse 5a). |
| Power Good Flag with Hysteresis | 65mV threshold offset + 10mV hysteresis ensures glitch-free system sequencing and avoids false resets during line transients. |
Applications
| Automotive Battery Regulation | Distributed Supply Regulation |
|---|---|
|
Use Scenario: Regulating 12V/24V vehicle battery rail to 5V/3.3V for ADAS camera modules and infotainment ECUs under cold-crank (–40°C) and load-dump (62V) conditions. IC Role / Device Role / Timing Role: Primary buck converter providing isolated, regulated DC power with OVP, thermal shutdown, and PG signaling for system safety monitoring. Use Value: Eliminates need for external TVS and pre-regulator stages; 75μA quiescent current extends key-off battery life beyond ISO 16750-2 requirements. |
Use Scenario: Point-of-load conversion in factory automation PLCs where 24V backplane supplies multiple 3.3V/5V rails for I/O modules and communication interfaces. IC Role / Device Role / Timing Role: High-current, thermally robust DC-DC stage delivering 3.5A with synchronized switching to minimize system-level EMI. Use Value: 3mm × 3mm DFN package enables dense multi-rail designs; SYNC pin allows interleaving with adjacent converters to reduce input capacitor RMS current. |
| Industrial Supplies | Wall Transformer Regulation |
|
Use Scenario: Replacing linear regulators in DIN-rail mounted HMIs and motor drives requiring 5V @ 3A from unregulated 18–36V DC inputs. IC Role / Device Role / Timing Role: Efficient, wide-input buck regulator with thermal protection and soft-start to handle inrush from large bulk capacitors. Use Value: 95mΩ switch and integrated boost diode achieve >92% efficiency at full load, reducing heatsink requirements and improving MTBF. |
Use Scenario: Secondary-side regulation in universal-input AC/DC adapters converting rectified ~12–36V DC to stable 5V USB-C PPS-compliant outputs. IC Role / Device Role / Timing Role: Post-regulator ensuring tight output tolerance (<±1.5%) and fast transient response for dynamic USB load changes. Use Value: Adjustable frequency allows EMI filtering at fixed bands; PG flag enables adapter status reporting to host controller via I²C or UART. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EMSE#TRPBF | 42V max input, 3.5A, 2MHz sync capability, 2.5μA IQ, no integrated boost diode - requires external Schottky. | Better suited for ultra-low-IQ battery apps; lacks BD pin bias-sourcing, limiting efficiency at VOUT > 3V. | Select when lowest possible shutdown current (<2.5μA) and 42V rating are critical; accept added BOM and layout complexity. |
| TPS54332DDAR | 28V max input, 3.5A, 570kHz fixed freq, 125μA IQ, integrated high-side MOSFET - no boost diode or BD pin. | Lower input voltage ceiling and higher quiescent current reduce suitability for 36V industrial or automotive transients. | Choose for cost-sensitive, non-transient-heavy 24V systems where 125μA IQ is acceptable and external diode is tolerable. |
Compared with LT8610EMSE#TRPBF and TPS54332DDAR, the LT3972IDD#TRPBF uniquely combines 62V transient tolerance, integrated boost diode, BD-bias capability, and 75μA Burst Mode IQ - making it optimal for space-constrained, high-reliability automotive and industrial buck applications where input robustness and light-load efficiency are co-prioritized.
Availability
LT3972IDD#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, distributed supply regulation, and industrial embedded power supplies requiring stable component supply, long-term lifecycle support, and guaranteed -40°C to 125°C operation.
Supply support for LT3972IDD#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 (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management ICs, serving aerospace, automotive, industrial, and communications markets with precision, reliability, and innovation.
The LT3972 belongs to Linear's high-voltage monolithic buck regulator product line, designed specifically for robust, wide-input industrial and automotive power conversion where transient immunity, thermal resilience, and low-light-load quiescent current are essential.
FAQ
What is the maximum input voltage the LT3972IDD#TRPBF can safely withstand?
The LT3972IDD#TRPBF has an absolute maximum VIN rating of 62V for non-repetitive 1-minute transients, with continuous operation rated up to 33V. Its overvoltage lockout activates at 33V (min), disabling switching to protect internal circuitry while sustaining the 62V transient - a key feature for automotive load-dump and industrial surge environments. This behavior is confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables of the official datasheet.
Does the LT3972IDD#TRPBF require an external boost diode?
No, the LT3972IDD#TRPBF integrates a boost Schottky diode on-die, eliminating the need for an external component. The BD pin connects directly to the anode of this internal diode, which supplies bias current to the internal regulator. This integration reduces solution size, BOM count, and layout complexity - a distinguishing feature versus competitors like the TPS54332DDAR that require external diodes.
How does the LT3972IDD#TRPBF achieve 75μA quiescent current?
The LT3972IDD#TRPBF achieves 75μA quiescent current through Low Ripple Burst Mode operation, which disables non-essential circuitry (oscillator, error amp, drivers) between switching bursts at light loads. This mode maintains output regulation while minimizing input current - verified at 12VIN → 3.3VOUT in the Typical Performance Characteristics section (Figure 3972 G01). The BD pin further enhances light-load efficiency by sourcing bias from VOUT when above 3V.
What package type and thermal characteristics does the LT3972IDD#TRPBF use?
The LT3972IDD#TRPBF uses a 10-lead 3mm × 3mm plastic DFN package with exposed thermal pad (Pin 11 = GND). Its thermal resistance is θJA = 45°C/W and θJC = 10°C/W when the exposed pad is properly soldered to a PCB ground plane - enabling reliable 3.5A operation at 125°C ambient without additional heatsinking, as validated in thermal performance plots (Figures 3972 G04–G05).
Can the LT3972IDD#TRPBF be synchronized to an external clock?
Yes, the LT3972IDD#TRPBF supports external clock synchronization via the SYNC pin, accepting TTL/CMOS signals from 250kHz to 2MHz. When synchronized, it locks its internal oscillator to the external source, eliminating beat frequencies and simplifying EMI filter design in multi-converter systems. If unused, SYNC must be grounded to ensure Burst Mode operation - a requirement explicitly stated in the Pin Functions section of the datasheet.
LT3972IDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN 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):
- 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#TRPBF FAQ
1.How can I place an order for LT3972IDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3972IDD#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 LT3972IDD#TRPBF reliable?
The price and inventory of LT3972IDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3972IDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3972IDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3972IDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3972IDD#TRPBF?
LT3972IDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3972IDD#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 LT3972IDD#TRPBF?
For technical support, including LT3972IDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3972IDD#TRPBF requirements.
6.How does Aetrix verify that LT3972IDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3972IDD#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 LT3972IDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3972IDD#TRPBF?
All LT3972IDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3972IDD#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 LT3972IDD#TRPBF part is unused and in its original packaging.
Return procedure for LT3972IDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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