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Analog Devices Inc. LT3973HDD-3.3#TRPBF
- Part No.:
- LT3973HDD-3.3#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3973HDD-3.3#TRPBF.pdf
- Description:
- IC REG BUCK 3.3V 750MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,219
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Product details
Overview
LT3973HDD-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a 42V, 750mA monolithic step-down regulator with integrated boost and catch diodes, fixed 3.3V output, 2.5µA quiescent current at 12VIN, and operation up to 150°C junction temperature. It delivers automotive cold-crank robustness with 530mV minimum dropout voltage and low-ripple Burst Mode™ operation for battery-powered industrial sensors and telematics power rails.
For engineers reviewing the LT3973HDD-3.3#TRPBF datasheet, LT3973HDD-3.3#TRPBF pinout, LT3973HDD-3.3#TRPBF application, or LT3973HDD-3.3#TRPBF equivalent, key selection criteria include high-temperature reliability (–40°C to 150°C), integrated diode architecture eliminating external components, programmable UVLO threshold, power good flag timing, and thermal performance in DFN packages with exposed pad.
Technical Context
The LT3973HDD-3.3#TRPBF uses current-mode control for fast transient response and stable loop behavior across wide input ranges (4.2V–42V). Its bipolar NPN internal switch is driven by a BOOST capacitor-based charge pump, enabling full saturation even during automotive dropout conditions where VIN approaches VOUT.
Burst Mode™ operation maintains <10mVP-P output ripple at light loads while reducing quiescent current to 1.8µA. The device integrates a 1.15A catch diode current limit, thermal shutdown, and accurate power good flag that asserts when VOUT reaches 90% of 3.3V - all within a 10-lead 3mm × 3mm DFN package with exposed GND pad.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.2% over –40°C to 150°C; eliminates external feedback resistors and reduces BOM count. |
| Input Voltage Range | 4.2V to 42V; supports 12V/24V/36V automotive and industrial bus systems including cold-crank transients. |
| Quiescent Current | 2.5µA at 12VIN/3.3VOUT; enables multi-year battery life in always-on IoT sensor nodes. |
| Max Output Current | 750mA continuous; sufficient for powering microcontrollers, CAN transceivers, and analog front-ends. |
| Switching Frequency | 200kHz to 2.2MHz via RT resistor; allows optimization of inductor size vs. efficiency in space-constrained designs. |
| Dropout Voltage | 530mV minimum; ensures regulation during deep automotive battery sag down to ~3.8V input at 3.3V output. |
| Operating Temperature | –40°C to 150°C junction; qualified for under-hood automotive and high-ambient industrial environments. |
Pinout & Package
LT3973HDD-3.3#TRPBF 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. θJA = 40°C/W, θJC = 5°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (Pin 1) | Fixed-output voltage reference node | Internally regulated to 3.3V; connects directly to output capacitor and load; replaces FB divider in adjustable variants. |
| OUT (Pin 2) | Dropout regulation and boost capacitor charging node | Tied to VOUT to enable 530mV dropout mode; supplies current to charge BOOST capacitor during low-VIN operation. |
| EN/UVLO (Pin 3) | Enable and programmable undervoltage lockout input | Active-high logic; 1.19V rising threshold with 30mV hysteresis; sets shutdown current to 0.75µA when pulled low. |
| VIN (Pin 4) | Main input power supply | Supplies internal circuitry and switch driver; rated to 42V absolute max; requires local 4.7µF ceramic bypass. |
| GND (Pin 5 & 11) | Power and signal ground reference | Pin 5 is signal GND; Pin 11 is exposed thermal pad - must be soldered to PCB copper for thermal management and noise reduction. |
| SW (Pin 6) | Internal switch drain node | Connects to inductor; switches between VIN and GND; carries peak currents up to 1.65A. |
| BOOST (Pin 7) | Charge-pump drive voltage node | Connected to BOOST capacitor; provides >VIN voltage to fully saturate internal bipolar NPN switch. |
| BD (Pin 8) | Boost diode anode and bias regulator input | Accepts external bias ≥3.2V (e.g., from VOUT) to improve efficiency by powering internal regulator externally. |
| PG (Pin 9) | Open-drain power good flag | Asserts high (via external pull-up) when VOUT ≥ 2.97V (90% of 3.3V); valid only when EN/UVLO is high and VIN > 4.2V. |
| RT (Pin 10) | Frequency-setting resistor connection | Resistor to GND programs switching frequency from 200kHz to 2.2MHz; enables trade-off between size and efficiency. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost and catch diodes | Eliminates 2 external Schottky diodes, reducing board area, BOM cost, and layout complexity in 3.3V point-of-load designs. |
| Low-ripple Burst Mode™ operation | Maintains output ripple <10mVP-P at light loads while achieving 1.8µA no-load supply current - critical for battery longevity. |
| Accurate programmable UVLO | EN/UVLO threshold (1.19V rising) with 30mV hysteresis enables precise system-level brown-out detection and controlled startup sequencing. |
| Power good flag with 90% threshold | PG output signals valid regulation at 2.97V, allowing safe microcontroller release from reset after stable 3.3V rail establishment. |
| Thermally enhanced DFN package | 3mm × 3mm footprint with exposed GND pad achieves θJC = 5°C/W - enables 750mA operation at 150°C ambient with proper PCB copper. |
Applications
| Automotive Telematics Module | Industrial Sensor Node |
|---|---|
Use Scenario: Powering GPS/GSM modules and MCU in vehicle tracking units exposed to under-hood temperatures up to 125°C ambient. IC Role / Device Role / Timing Role: Primary 3.3V buck regulator supplying core logic, RF interface, and serial peripherals. Use Value: 150°C-rated operation ensures reliability during extended engine runtime; 530mV dropout sustains regulation during 6V cold-crank events. |
Use Scenario: Long-life battery-powered vibration/temperature sensor deployed in factory automation equipment. IC Role / Device Role / Timing Role: Always-on 3.3V supply for ultra-low-power MCU and analog signal chain during sleep and wake cycles. Use Value: 2.5µA quiescent current extends 10-year battery life; integrated diodes reduce leakage paths and improve shelf-life stability. |
| Medical Portable Monitor | Smart Building Controller |
Use Scenario: Compact, fanless patient monitor requiring EMI-controlled, ripple-free 3.3V rail for ADCs and touch interface. IC Role / Device Role / Timing Role: Main DC/DC converter delivering clean, regulated 3.3V from 9–36V medical-grade input. Use Value: Burst Mode™ keeps output ripple <10mVP-P without audible coil whine; PG flag synchronizes display initialization. |
Use Scenario: DIN-rail mounted HVAC controller operating continuously in unconditioned mechanical rooms (–25°C to 70°C ambient). IC Role / Device Role / Timing Role: Robust 3.3V supply for ARM Cortex-M7 MCU, Ethernet PHY, and isolated I/O drivers. Use Value: 42V input rating handles 24VAC-to-DC rectified surges; thermal design supports 750mA load at 70°C ambient without derating. |
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-3.3#TRPBF | 40V input, 500mA output, 1.2µA IQ, MSOP-10 package, no integrated catch diode | Lower current capability and no integrated catch diode require external Schottky; better suited for ultra-low-IQ sub-500mA applications | Select when lowest possible quiescent current (<1.5µA) is prioritized over output current and component count. |
| TPS54332DR | 28V input, 3.5A output, 12µA IQ, SOIC-8, external diode required, no PG flag | Higher current but larger package and no power good output; lacks automotive temperature grade and cold-crank support | Select when higher output current (≥2A) is needed and 150°C operation is not required. |
Compared with LTC3631EMSE-3.3#TRPBF and TPS54332DR, the LT3973HDD-3.3#TRPBF uniquely combines 750mA output, integrated diodes, 150°C rating, and 2.5µA IQ in a compact DFN - making it optimal for space-constrained, high-reliability automotive and industrial 3.3V point-of-load designs.
Availability
LT3973HDD-3.3#TRPBF is available at Aetrix Electronics and suitable for automotive telematics, industrial sensor nodes, portable medical monitors, and smart building controllers requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3973HDD-3.3#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 and continues to develop and support its high-performance power management portfolio, emphasizing precision, reliability, and ruggedness for demanding applications.
The LT3973 family was designed specifically for automotive and industrial DC/DC conversion where wide input range, ultra-low quiescent current, integrated diodes, and high-temperature operation are mandatory - targeting cold-crank resilience and long-term field reliability.
FAQ
What is the maximum junction temperature specification for LT3973HDD-3.3#TRPBF?
The LT3973HDD-3.3#TRPBF is fully specified and guaranteed over a junction temperature range of –40°C to 150°C. This H-grade qualification makes it suitable for under-hood automotive applications and high-ambient industrial environments where standard E- or I-grade parts would fail. Thermal design must ensure θJA and PCB copper area maintain TJ ≤ 150°C under worst-case load and ambient conditions.
Does LT3973HDD-3.3#TRPBF require external feedback resistors?
No. The LT3973HDD-3.3#TRPBF features a factory-trimmed internal feedback divider that regulates the VOUT pin precisely to 3.3V ±1.2% across temperature and line. Unlike the adjustable LT3973 variant, it does not use the FB pin - eliminating two external resistors, associated tolerance errors, and PCB routing overhead.
How does LT3973HDD-3.3#TRPBF achieve low output ripple in Burst Mode™ operation?
The LT3973HDD-3.3#TRPBF maintains output ripple below 10mVP-P in Burst Mode™ by tightly controlling burst energy and minimizing switching node ringing. Its integrated catch diode and optimized gate drive reduce EMI, while the internal error amplifier dynamically adjusts burst depth to balance efficiency and ripple - verified in typical applications with 22µF output capacitance.
Can LT3973HDD-3.3#TRPBF operate during automotive cold-crank conditions?
Yes. The LT3973HDD-3.3#TRPBF sustains regulation down to 3.8V input (minimum operating voltage) and maintains 530mV minimum dropout voltage - enabling continuous 3.3V output even when battery voltage sags to ~3.8V during cold-crank. Its 42V absolute maximum input rating also protects against load-dump transients.
What is the function of the BD pin on LT3973HDD-3.3#TRPBF?
The BD (Bias Diode) pin on LT3973HDD-3.3#TRPBF serves dual roles: it connects to the anode of the external boost diode, and - when held ≥3.2V - powers the internal bias regulator from the output rail instead of VIN. This improves efficiency by reducing input current draw, especially at high input voltages, and is confirmed in the LT3973HDD-3.3#TRPBF datasheet Section "Operation".
LT3973HDD-3.3#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:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.2V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 750mA
- Frequency - Switching:
- 195kHz ~ 2.15MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3973HDD-3.3#TRPBF FAQ
1.How can I place an order for LT3973HDD-3.3#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973HDD-3.3#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 LT3973HDD-3.3#TRPBF reliable?
The price and inventory of LT3973HDD-3.3#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3973HDD-3.3#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3973HDD-3.3#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973HDD-3.3#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973HDD-3.3#TRPBF?
LT3973HDD-3.3#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973HDD-3.3#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 LT3973HDD-3.3#TRPBF?
For technical support, including LT3973HDD-3.3#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973HDD-3.3#TRPBF requirements.
6.How does Aetrix verify that LT3973HDD-3.3#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3973HDD-3.3#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 LT3973HDD-3.3#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3973HDD-3.3#TRPBF?
All LT3973HDD-3.3#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973HDD-3.3#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 LT3973HDD-3.3#TRPBF part is unused and in its original packaging.
Return procedure for LT3973HDD-3.3#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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