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Analog Devices Inc. LT3973IMSE-3.3#TRPBF
- Part No.:
- LT3973IMSE-3.3#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3973IMSE-3.3#TRPBF.pdf
- Description:
- IC REG BUCK 3.3V 750MA 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,535
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Product details
Overview
LT3973IMSE-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a fixed 3.3V, 42V-input, 750mA monolithic buck regulator with integrated boost and catch diodes, 2.5µA quiescent current, and low-ripple Burst Mode operation. It delivers automotive-grade power regulation in cold-crank scenarios while maintaining <10mVP-P output ripple at light loads.
For engineers reviewing the LT3973IMSE-3.3#TRPBF datasheet, LT3973IMSE-3.3#TRPBF pinout, LT3973IMSE-3.3#TRPBF application, or LT3973IMSE-3.3#TRPBF equivalent, key selection criteria include its 530mV minimum dropout voltage, programmable UVLO, open-drain power-good flag, and thermally enhanced 10-lead MSOP package rated for –40°C to 125°C operation.
Technical Context
The LT3973IMSE-3.3#TRPBF employs current-mode control for fast transient response and loop stability, with internal bipolar NPN switch driven via BOOST pin to ensure full saturation. Its architecture integrates all power diodes-catch and boost-eliminating external components while enabling ultralow IQ operation down to 1.8µA in Burst Mode.
It features dual current limiting: peak switch current limit (1.65A typ) and valley catch diode current limit (1.15A typ), providing robust short-circuit protection. The device maintains regulation during automotive cold-crank by enforcing a 530mV minimum dropout and extending duty cycle up to ~97.5% when VIN approaches VOUT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.2% over –40°C to 125°C; enables direct replacement of LDOs in noise-sensitive digital rails. |
| Input Voltage Range | 4.2V to 42V; supports 12V/24V/36V automotive and industrial battery inputs without external pre-regulation. |
| Quiescent Current | 2.5µA at 12VIN → 3.3VOUT; sustains >1-year battery life in always-on telematics or sensor nodes. |
| Output Ripple | <10mVP-P in Burst Mode; meets stringent noise requirements for RF, ADC, and MCU core supplies. |
| Switching Frequency | 200kHz to 2.2MHz (RT-programmable); allows optimization of inductor size vs. EMI vs. efficiency across applications. |
| Thermal Rating | –40°C to 125°C junction; qualified for under-hood automotive modules and industrial control cabinets. |
| Package | 10-lead plastic MSOP with exposed pad; θJA = 45°C/W enables 750mA continuous output without forced air. |
Pinout & Package
LT3973IMSE-3.3#TRPBF is housed in a thermally enhanced 10-lead plastic MSOP package with an exposed GND pad (Pin 11) that must be soldered to PCB for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (Pin 1) | Fixed-output feedback node | Internally regulated to 3.3V; connects directly to output capacitor-no external resistor divider required. |
| OUT (Pin 2) | Dropout regulation reference | Enables minimum dropout operation; tie to VOUT to enforce ≥530mV VIN–VOUT differential during cold-crank. |
| EN/UVLO (Pin 3) | Enable and undervoltage lockout input | 1.19V threshold with 30mV hysteresis; supports programmable brown-in/brown-out for system-level power sequencing. |
| VIN (Pin 4) | Main power input | Supplies internal circuitry and switch; requires local 4.7µF X7R ceramic bypass per datasheet layout guidelines. |
| GND (Pin 5 & 11) | Power and signal ground | Pin 11 is exposed thermal pad-must be soldered to ≥1 cm² copper pour for thermal management. |
| SW (Pin 6) | Switch node | Drives external inductor; high dV/dt node requiring tight layout and Kelvin connection to minimize EMI. |
| BOOST (Pin 7) | Bootstrap drive supply | Accepts charge from external capacitor to drive internal NPN switch; max 55V rating enables high-VIN operation. |
| BD (Pin 8) | Boost diode anode | Connects to boost diode cathode; also powers internal bias regulator when >3.2V, improving light-load efficiency. |
| PG (Pin 9) | Power-good open-drain flag | Asserts high when VOUT reaches 90% of 3.3V; used for processor reset, sequencer enable, or fault monitoring. |
| RT (Pin 10) | Frequency set resistor | Grounded via precision resistor (e.g., 215kΩ for 600kHz); sets switching frequency and impacts inductor/capacitor sizing. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated power diodes | Eliminates 2 external Schottky diodes-reduces BOM count, PCB area, and assembly cost in space-constrained designs. |
| Low-ripple Burst Mode | Maintains <10mVP-P output ripple at µA load currents-critical for powering noise-sensitive analog or RF subsystems. |
| Accurate programmable UVLO | EN/UVLO threshold tolerance ±30mV with hysteresis-enables precise system-level brownout detection and wake-up control. |
| Power-good flag with 10% threshold | PG asserts when VOUT ≥ 2.97V-provides reliable system initialization signal without external monitoring circuitry. |
| Thermally enhanced MSOP | θJA = 45°C/W with exposed pad-delivers full 750mA output in ambient up to 85°C without heatsink or airflow. |
Applications
| Automotive Body Control Module | Industrial IoT Sensor Node |
|---|---|
Use Scenario: Powering microcontroller, CAN transceiver, and LIN interface in door module during vehicle start-stop cycles. IC Role / Device Role / Timing Role: Primary 3.3V buck regulator delivering stable rail despite 4.5V–42V battery transients and cold-crank dips. Use Value: 530mV dropout and 2.5µA IQ extend battery runtime and ensure reliable operation below 6V input-meeting ISO 16750-2 pulse 4 requirements. | Use Scenario: Supplying ultra-low-power MCU, BLE radio, and environmental sensors in battery-operated predictive maintenance node. IC Role / Device Role / Timing Role: Main system regulator enabling multi-year operation on primary Li-SOCl₂ cell with periodic wake-up bursts. Use Value: 1.8µA shutdown current and <10mVP-P Burst Mode ripple preserve battery capacity and prevent radio desense during sleep/wake transitions. |
| Portable Medical Diagnostic Device | Programmable Logic Controller I/O Module |
Use Scenario: Generating clean 3.3V supply for ADC, op-amps, and display controller in handheld ultrasound probe. IC Role / Device Role / Timing Role: Low-noise power source for analog front-end and digital logic, co-located on compact PCB. Use Value: Integrated diodes and <10mVP-P ripple eliminate need for external filtering-reducing board area and EMI risk in FDA-cleared Class II devices. | Use Scenario: Providing isolated 3.3V logic rail for digital I/O ASICs and level translators in DIN-rail mounted PLC backplane. IC Role / Device Role / Timing Role: Secondary regulator fed from 24V industrial bus, supporting hot-swap and reverse-polarity protection. Use Value: 42V absolute max input rating and robust thermal design allow direct connection to unregulated 24V supply-reducing system component count and failure points. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8609SIS8E#TRPBF | 42V input, 3.3V fixed, 2A output; synchronous rectification; 2.5µA IQ; 3mm × 4mm TSOT-23-8 package. | Higher output current capability; smaller footprint but lower thermal mass; no integrated boost diode-requires external bootstrap cap. | Select when >750mA load or tighter board area is required; verify thermal margin at full load in sealed enclosure. |
| TPS54332DDAR | 28V input, adjustable output, 3A output; external diode; 125µA IQ; SOIC-8 package; no PG flag or UVLO programming. | Lower input voltage range; higher IQ limits battery life; lacks power-good and accurate UVLO-requires external monitoring. | Select only for cost-sensitive industrial supplies where 42V rating and ultralow IQ are not required. |
Compared with LT3973IMSE-3.3#TRPBF, LT8609SIS8E#TRPBF offers higher current and smaller size but sacrifices integrated boost diode and PG functionality; TPS54332DDAR provides higher current at lower cost but lacks automotive-grade input range, low-IQ operation, and system-level monitoring features critical for battery or safety-critical designs.
Availability
LT3973IMSE-3.3#TRPBF is available at Aetrix Electronics and suitable for automotive body electronics, industrial IoT sensor nodes, portable medical diagnostics, and programmable logic controller I/O modules requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3973IMSE-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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving automotive, industrial, communications, and healthcare markets.
The LT3973 family was designed specifically for high-input-voltage, ultralow-quiescent-current DC/DC conversion in harsh environments-targeting automotive infotainment, ADAS domain controllers, and industrial edge nodes where reliability and efficiency are non-negotiable.
FAQ
What is the guaranteed operating temperature range for LT3973IMSE-3.3#TRPBF?
The LT3973IMSE-3.3#TRPBF is guaranteed to operate over –40°C to 125°C junction temperature. This "I-grade" rating is validated across process, voltage, and temperature corners-not just characterized-and applies to all electrical specifications in the datasheet's "l" column. The 10-lead MSOP package with exposed pad ensures thermal performance aligns with this rating under typical PCB copper pours.
Does LT3973IMSE-3.3#TRPBF require external feedback resistors?
No. The LT3973IMSE-3.3#TRPBF is the fixed 3.3V variant-its internal feedback divider is factory-trimmed to regulate the VOUT pin (Pin 1) precisely to 3.3V ±1.2%. Unlike the adjustable LT3973, it eliminates external R1/R2 resistors, reducing BOM count, layout complexity, and potential drift sources in production.
How does LT3973IMSE-3.3#TRPBF achieve 530mV minimum dropout?
The LT3973IMSE-3.3#TRPBF enforces a 530mV minimum VIN–VOUT differential by regulating the OUT pin (Pin 2) to maintain ≥530mV headroom. When VIN drops near 3.3V, the IC extends duty cycle up to ~97.5% and skips switch-off periods-keeping the boost capacitor charged and the internal NPN switch saturated-ensuring regulation even during automotive cold-crank events.
Can LT3973IMSE-3.3#TRPBF be used with input voltages below 4.2V?
Yes-but regulation degrades. The LT3973IMSE-3.3#TRPBF begins switching at ~3V, yet its FB reference accuracy and UVLO function are only specified above 4.2V. Below this, output voltage may deviate beyond ±1.2%, and EN/UVLO thresholds become inaccurate. For sub-4.2V operation, use external supervision or validate performance empirically per application conditions.
What is the role of the BD pin on LT3973IMSE-3.3#TRPBF?
The BD pin on LT3973IMSE-3.3#TRPBF serves two functions: (1) it connects to the anode of the external boost diode, and (2) when biased above 3.2V (e.g., from VOUT), it powers the internal bias regulator-bypassing VIN and improving light-load efficiency. This dual-role design reduces power loss and simplifies supply routing in fixed-output configurations.
LT3973IMSE-3.3#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) 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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LT3973IMSE-3.3#TRPBF FAQ
1.How can I place an order for LT3973IMSE-3.3#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973IMSE-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 LT3973IMSE-3.3#TRPBF reliable?
The price and inventory of LT3973IMSE-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 LT3973IMSE-3.3#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3973IMSE-3.3#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973IMSE-3.3#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973IMSE-3.3#TRPBF?
LT3973IMSE-3.3#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973IMSE-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 LT3973IMSE-3.3#TRPBF?
For technical support, including LT3973IMSE-3.3#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973IMSE-3.3#TRPBF requirements.
6.How does Aetrix verify that LT3973IMSE-3.3#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3973IMSE-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 LT3973IMSE-3.3#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3973IMSE-3.3#TRPBF?
All LT3973IMSE-3.3#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973IMSE-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 LT3973IMSE-3.3#TRPBF part is unused and in its original packaging.
Return procedure for LT3973IMSE-3.3#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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