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Analog Devices Inc. LT3973IDD-5#PBF
- Part No.:
- LT3973IDD-5#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3973IDD-5#PBF.pdf
- Description:
- IC REG BUCK 5V 750MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:819
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Product details
Overview
LT3973IDD-5#PBF from Analog Devices (formerly Linear Technology) is a 42V, 750mA monolithic step-down DC/DC regulator with integrated boost and catch Schottky diodes, 2.5µA quiescent current, and fixed 5V output. It employs current-mode control for fast transient response and maintains regulation down to 530mV dropout-critical for automotive cold-crank conditions. Designed for high-efficiency power conversion in space-constrained industrial and automotive systems.
For engineers reviewing the LT3973IDD-5#PBF datasheet, LT3973IDD-5#PBF pinout, LT3973IDD-5#PBF application, or LT3973IDD-5#PBF equivalent, key selection criteria include its 5V fixed output, 10-lead 3mm × 3mm DFN package, –40°C to 125°C operating range, low-noise Burst Mode operation (<10mVP-P ripple), and programmable UVLO via EN/UVLO pin.
Technical Context
The LT3973IDD-5#PBF implements a constant-frequency current-mode buck topology with internal bipolar NPN switch, integrated boost and catch diodes, and thermal shutdown. Its minimum on-time of 70ns and adjustable switching frequency (200kHz–2.2MHz via RT resistor) enable stable operation across wide input ranges (4.2V–42V) while supporting high VIN/VOUT ratios.
Operation includes low-ripple Burst Mode at light loads (1.8µA IQ), accurate 5V output regulation (±1.2% over temperature), power-good flag signaling at 90% VOUT, and dual current limiting: 1.65A switch peak limit and 1.15A catch diode valley limit-providing robust short-circuit protection without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.0V ±1.2% over –40°C to 125°C; eliminates external feedback resistors. |
| Input Voltage Range | 4.2V to 42V continuous; supports 12V/24V/36V automotive and industrial rails. |
| Max Output Current | 750mA continuous; limited by thermal design and 1.15A catch diode valley current. |
| Quiescent Current | 2.5µA at 12VIN → 5VOUT; enables always-on battery-powered applications. |
| Switching Frequency | 200kHz to 2.2MHz via RT pin; allows optimization of inductor size vs. efficiency. |
| Dropout Voltage | 530mV minimum (VIN – VOUT); ensures regulation during automotive cold-crank events. |
| Package | 10-lead 3mm × 3mm plastic DFN with exposed thermal pad; θJA = 40°C/W. |
Pinout & Package
LT3973IDD-5#PBF is housed in a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed GND pad (Pin 11) requiring PCB soldering for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB/VOUT (Pin 1) | Fixed-output voltage sense | Internally connected to 5V feedback divider; no external resistor required. |
| OUT (Pin 2) | Dropout regulation node | Enables minimum dropout mode; tie to VOUT for 530mV dropout enforcement. |
| EN/UVLO (Pin 3) | Enable & programmable UVLO input | 1.19V rising threshold with 45mV hysteresis; supports system-level brownout control. |
| VIN (Pin 4) | Main power input | Supplies internal circuitry and switch; requires local 4.7µF ceramic bypass. |
| GND (Pin 5 & Exposed Pad 11) | Power and signal reference | Exposure pad must be soldered to PCB plane for thermal performance and noise reduction. |
| SW (Pin 6) | Switch node | Connects to inductor; carries high di/dt; requires tight layout and Kelvin grounding. |
| BOOST (Pin 7) | Bootstrap drive supply | Drives internal NPN switch; requires 0.47µF ceramic capacitor to SW. |
| BD (Pin 8) | Bias diode anode | Accepts external bias >3.2V (e.g., VOUT) to improve light-load efficiency. |
| PG (Pin 9) | Open-drain power-good flag | Asserts high when VOUT reaches 90% of 5V; requires external pull-up resistor. |
| RT (Pin 10) | Frequency programming | Resistor-to-GND sets switching frequency; 158kΩ yields ~600kHz typical. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost & catch diodes | Eliminates 2 external Schottky diodes; reduces BOM count and board area in 5V point-of-load designs. |
| Low-ripple Burst Mode | Maintains <10mVP-P output ripple at light loads while achieving 1.8µA IQ-ideal for sensor nodes and standby circuits. |
| Accurate 5V output | ±1.2% tolerance over full temperature and line range; meets USB-compliant and microcontroller I/O rail requirements. |
| Thermal shutdown + current limits | Combines 1.65A switch peak limit, 1.15A catch diode valley limit, and thermal foldback-enables self-protected operation without external sensing. |
| Automotive-grade temperature range | –40°C to 125°C junction rating; qualified per AEC-Q100 stress test guidelines for under-hood use. |
Applications
| Automotive Battery Regulation | Industrial Sensor Power |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery to stable 5V for ECU peripherals during cold-crank (VIN drops to 3.5V). IC Role / Device Role / Timing Role: Primary 5V buck regulator with enforced 530mV dropout and UVLO hysteresis to prevent brownout resets. Use Value: Maintains 5V output down to VIN = 5.53V (5V + 530mV), enabling uninterrupted operation through ISO 16750-2 cranking pulses. | Use Scenario: Powering low-power analog sensors and transmitters in factory automation cabinets with 24V DC rails. IC Role / Device Role / Timing Role: Fixed-output DC/DC converter delivering clean 5V at <2.5µA quiescent current for battery-backed or energy-harvested nodes. Use Value: Enables >10-year battery life in wireless sensor modules due to ultra-low IQ and integrated diodes reducing leakage paths. |
| Gate Drive Bias Supply | Portable Medical Device Power |
Use Scenario: Generating isolated 5V bias for high-side MOSFET gate drivers in motor inverters or SMPS half-bridges. IC Role / Device Role / Timing Role: Compact, high-VIN buck stage providing regulated 5V to driver ICs with fast transient response to gate charge demands. Use Value: Delivers 750mA peak current with <70ns minimum on-time, supporting high-frequency PWM gate driving up to 2MHz. | Use Scenario: Powering microcontroller, display, and Bluetooth SoC in handheld diagnostic tools powered by single-cell Li-ion (3.0–4.2V) or dual-cell alkaline. IC Role / Device Role / Timing Role: Wide-input buck regulator accepting 4.2V–42V, enabling direct connection to unregulated wall adapters or multi-cell battery packs. Use Value: Supports input as low as 4.2V while delivering precise 5V-eliminating need for pre-regulation stages in portable medical BOMs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fixed-output buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8609SIS8E#TRPBF | 42V input, 5V fixed, 2A output, 2.5µA IQ, 3mm × 4mm SO-8 package | Higher current capability; requires external catch diode; different pinout and layout | Select when >750mA load or SO-8 assembly preference exists; verify thermal derating at 125°C. |
| TPS54560QDGQRQ1 | 60V input, 5V fixed, 5A output, 14.5µA IQ, 10-pin MSOP package | Higher VIN max and IOUT; higher quiescent current; AEC-Q100 qualified but no integrated catch diode | Choose for 48V industrial systems or where 5A headroom is needed; add external Schottky for catch path. |
Compared with LT3973IDD-5#PBF, LT8609SIS8E#TRPBF offers double the output current in a larger SO-8 but lacks integrated catch diode, increasing BOM and layout complexity; TPS54560QDGQRQ1 supports higher input voltage and current but consumes 5.8× more quiescent current-making it unsuitable for always-on battery applications.
Availability
LT3973IDD-5#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial sensor power, and gate drive bias applications requiring stable component supply, extended temperature operation, and long-term lifecycle continuity.
Supply support for LT3973IDD-5#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 its high-performance power management portfolio with rigorous qualification standards and automotive-grade reliability testing.
The LT3973 family was designed specifically for high-input-voltage, low-quiescent-current buck conversion in harsh environments-targeting automotive infotainment, ADAS camera modules, and industrial PLC I/O power rails.
FAQ
What is the guaranteed operating temperature range for LT3973IDD-5#PBF?
The LT3973IDD-5#PBF is specified for –40°C to 125°C junction temperature operation. The "I" grade designation confirms full performance validation across this range, including feedback accuracy, current limits, and UVLO thresholds-making it suitable for under-hood automotive and industrial control cabinet deployments where ambient temperatures exceed 85°C.
Does LT3973IDD-5#PBF require external feedback resistors to set the 5V output?
No. The LT3973IDD-5#PBF integrates the feedback divider for its fixed 5V output. Pin 1 is labeled VOUT (not FB), and internal resistors are trimmed to deliver 5.0V ±1.2% over temperature and line-eliminating external resistor placement, tolerance errors, and board space. This distinguishes it from the adjustable LT3973 variant.
How does the LT3973IDD-5#PBF achieve 530mV minimum dropout?
The LT3973IDD-5#PBF enforces a minimum 530mV dropout by regulating the OUT pin (Pin 2) relative to VIN. When OUT is tied to VOUT, the internal comparator holds the output at least 530mV below VIN-even during automotive cold-crank events-ensuring sufficient boost capacitor voltage to saturate the internal NPN switch and maintain regulation.
Can LT3973IDD-5#PBF operate with input voltages below 4.2V?
Yes, the LT3973IDD-5#PBF begins switching at ~3V input but only guarantees 5V regulation above 4.2V. Below that, FB reference accuracy degrades and output voltage drops proportionally. For sub-4.2V operation, tie EN/UVLO to GND to force shutdown, or use external supervision to disable the part until VIN exceeds 4.2V.
What is the purpose of the BD pin on LT3973IDD-5#PBF?
On the LT3973IDD-5#PBF, the BD (Bias Diode) pin accepts an external voltage >3.2V-typically the regulated 5V output-to power the internal bias regulator. This bypasses VIN-derived bias current, reducing total quiescent consumption by ~0.7µA and improving light-load efficiency, especially in battery-powered applications where every nanoamp counts.
LT3973IDD-5#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:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.2V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- -
- Current - Output:
- 750mA
- Frequency - Switching:
- 195kHz ~ 2.15MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3973IDD-5#PBF FAQ
1.How can I place an order for LT3973IDD-5#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973IDD-5#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 LT3973IDD-5#PBF reliable?
The price and inventory of LT3973IDD-5#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3973IDD-5#PBF is usually 5 days.
3.What payment methods are accepted for LT3973IDD-5#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973IDD-5#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973IDD-5#PBF?
LT3973IDD-5#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973IDD-5#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 LT3973IDD-5#PBF?
For technical support, including LT3973IDD-5#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973IDD-5#PBF requirements.
6.How does Aetrix verify that LT3973IDD-5#PBF is sourced from the original manufacturer or authorized distributors?
All LT3973IDD-5#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 LT3973IDD-5#PBF meets industry standards.
7.What is the process for return or replacement of LT3973IDD-5#PBF?
All LT3973IDD-5#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973IDD-5#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 LT3973IDD-5#PBF part is unused and in its original packaging.
Return procedure for LT3973IDD-5#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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