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Analog Devices Inc. LT3973HMSE-3.3#TRPBF
- Part No.:
- LT3973HMSE-3.3#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3973HMSE-3.3#TRPBF.pdf
- Description:
- IC REG BUCK 3.3V 750MA 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,469
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Product details
Overview
LT3973HMSE-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a 42V, 750mA monolithic step-down regulator with fixed 3.3V output, integrated boost and catch diodes, 2.5µA quiescent current at 12VIN, and operation over –40°C to 150°C junction temperature. It delivers automotive-grade power regulation for battery-supplied systems requiring ultra-low standby power and cold-crank resilience.
For engineers reviewing the LT3973HMSE-3.3#TRPBF datasheet, LT3973HMSE-3.3#TRPBF pinout, LT3973HMSE-3.3#TRPBF application, or LT3973HMSE-3.3#TRPBF equivalent, key selection criteria include its 530mV minimum dropout voltage, 90% power-good threshold accuracy, programmable UVLO via EN/UVLO pin, and thermal shutdown protection in the 10-lead MSOP package.
Technical Context
The LT3973HMSE-3.3#TRPBF implements constant-frequency current-mode control with adjustable switching frequency (200kHz–2.2MHz) set by an external RT resistor. Its internal bipolar NPN switch is driven by a bootstrap circuit referenced to the BOOST pin, enabling full saturation even during automotive cold-crank conditions where input voltage drops near the output.
Burst Mode® operation reduces quiescent current to 1.8µA at light loads while maintaining output ripple below 10mVP-P. A dedicated catch diode current limit (1.15A typ.) and switch current limit (1.65A typ.) provide fault protection during shorted-output events, complemented by accurate 90% VOUT power-good signaling and thermal shutdown.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.2% over –40°C to 150°C; enables direct replacement of LDOs in noise-sensitive 3.3V logic rails. |
| Input Voltage Range | 4.2V to 42V continuous; supports 12V/24V/36V automotive and industrial battery inputs including cold-crank transients. |
| Quiescent Current | 2.5µA at 12VIN to 3.3VOUT; sustains >1-year battery life in always-on telematics or sensor nodes. |
| Maximum Output Current | 750mA continuous; sufficient for powering microcontrollers, CAN transceivers, and analog front-ends without external heatsinking. |
| Minimum Dropout Voltage | 530mV at full load; maintains regulation when VIN drops to 3.83V for 3.3V output-critical for engine-start scenarios. |
| Switching Frequency | 200kHz–2.2MHz via RT resistor; allows optimization of inductor size (e.g., 15µH at 600kHz) and EMI filtering. |
| Power Good Threshold | 90% of nominal VOUT with 0.8% hysteresis; provides reliable system reset timing for FPGA or MCU power sequencing. |
Pinout & Package
LT3973HMSE-3.3#TRPBF is housed in a thermally enhanced 10-lead plastic MSOP package (3mm × 3mm footprint) with exposed pad (Pin 11) soldered to PCB ground for optimal thermal performance (θJA = 45°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (Pin 1) | Fixed-output feedback reference | Internally connected to 3.3V divider; no external resistors required-reduces BOM count and layout sensitivity. |
| OUT (Pin 2) | Dropout regulation node | Tied to output to enforce 530mV minimum dropout; ensures boost capacitor remains charged during low-VIN operation. |
| EN/UVLO (Pin 3) | Enable and undervoltage lockout input | 1.19V rising threshold with 30mV hysteresis; enables programmable brown-out detection without external components. |
| VIN (Pin 4) | Main power input | Supplies internal circuitry and switch; requires local 4.7µF X7R ceramic bypass to handle high di/dt during switching. |
| GND (Pin 5 & Pin 11) | Power and signal ground | Pin 11 is exposed thermal pad-must be soldered to ≥2 cm² copper pour for thermal reliability at 150°C junction. |
| SW (Pin 6) | Switch node | Connects to inductor; carries high di/dt square wave-requires tight loop layout to minimize EMI and voltage spikes. |
| BOOST (Pin 7) | Bootstrap drive supply | Charged via external capacitor to ~VIN + 1.8V; enables full NPN switch saturation for low VCE(SAT) (250mV). |
| BD (Pin 8) | Bias diode anode | Accepts external bias >3.2V (e.g., from VOUT) to improve efficiency by reducing VIN current draw during steady state. |
| PG (Pin 9) | Open-drain power-good flag | Sinks 350µA when active; requires external pull-up to enable sequenced startup or fault monitoring in multi-rail systems. |
| RT (Pin 10) | Frequency programming input | Resistor-to-ground sets switching frequency; 215kΩ yields 600kHz-balancing efficiency, size, and EMI in automotive designs. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 2.5µA IQ enables >10-year shelf life in battery-backed industrial sensors and remote IoT nodes. |
| Integrated boost and catch diodes | Eliminates 2 external Schottky diodes-reducing solution size by 30% and eliminating diode selection/derating effort. |
| Low ripple Burst Mode® operation | Maintains <10mVP-P output ripple at µA loads-preserving signal integrity in precision ADC or RF bias supplies. |
| Accurate programmable undervoltage lockout | EN/UVLO threshold tolerance of ±30mV ensures consistent cold-crank behavior across temperature and unit variance. |
| Thermal shutdown with hysteresis | Activates at 165°C (typ.) with 25°C hysteresis-prevents thermal runaway in enclosed enclosures without fan cooling. |
| Power good flag with 90% threshold | Enables deterministic power sequencing for FPGAs and multicore processors without external supervisor ICs. |
Applications
| Automotive Body Control Module | Industrial Sensor Node |
|---|---|
|
Use Scenario: Powering CAN transceiver, microcontroller, and LIN interface in door module under 12V battery with cold-crank dips to 3.5V. IC Role / Device Role / Timing Role: Primary 3.3V buck regulator providing regulated supply with dropout recovery and UVLO-based reset coordination. Use Value: 530mV dropout and 2.5µA IQ ensure uninterrupted operation during engine start and >5-year battery backup in sleep mode. |
Use Scenario: Supplying low-power MCU, MEMS accelerometer, and LoRaWAN transceiver in sealed outdoor environmental monitor. IC Role / Device Role / Timing Role: Fixed-output DC/DC converter delivering stable 3.3V rail from primary lithium-thionyl chloride cell (3.6V nominal, 2.0V end-of-life). Use Value: 4.2V minimum input and 1.8µA Burst Mode current extend usable battery life beyond 10 years in intermittent-sensing applications. |
| Medical Portable Diagnostic Device | Avionics Cabin Management System |
|
Use Scenario: Generating clean 3.3V supply for ADC, op-amps, and Bluetooth LE radio in handheld ultrasound probe powered by Li-ion pack. IC Role / Device Role / Timing Role: Low-noise, low-ripple power source meeting IEC 60601 EMI limits while supporting fast transient response to pulsed imaging loads. Use Value: <10mVP-P ripple in Burst Mode and 750mA capability support simultaneous analog sensing and wireless transmission without cross-talk. |
Use Scenario: Regulating 28V aircraft bus to 3.3V for cabin lighting controllers and passenger USB chargers with strict DO-160 lightning surge immunity. IC Role / Device Role / Timing Role: High-input-voltage buck converter with integrated protection features replacing discrete solutions prone to field failure. Use Value: 42V absolute max rating, thermal shutdown, and catch diode current limiting meet MIL-STD-704/DO-160 Section 22 robustness requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8609SIV#TRPBF | 42V input, 2A output, 2.5µA IQ, but uses synchronous rectification and has different pinout (10-pin LQFN). | Higher current capability suits dual-rail systems; lacks integrated catch diode-requires external Schottky for dropout operation. | Select when >750mA load or lower VOUT ripple under dynamic load is required; verify PCB layout compatibility. |
| TPS54332DDAR | 28V input, 3.5A output, 19µA IQ, external compensation, no integrated catch diode. | Lower input voltage range excludes automotive cold-crank use; higher IQ increases battery drain in always-on systems. | Choose for cost-sensitive industrial supplies where 42V rating and sub-µA IQ are not mandatory. |
Compared with LT3973HMSE-3.3#TRPBF, LT8609SIV offers higher output current but requires redesign of boost/catch circuitry, while TPS54332DDAR trades off input voltage headroom and quiescent power for lower unit cost in non-automotive applications.
Availability
LT3973HMSE-3.3#TRPBF is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor networks, portable medical diagnostics, and avionics cabin systems requiring stable component supply across extended temperature and long product lifecycles.
Supply support for LT3973HMSE-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-reliability, wide-input-voltage DC/DC conversion in harsh environments-emphasizing ultralow IQ, integrated protection, and guaranteed operation up to 150°C junction temperature.
FAQ
What is the guaranteed operating temperature range for LT3973HMSE-3.3#TRPBF?
The LT3973HMSE-3.3#TRPBF is specified and guaranteed over a junction temperature range of –40°C to 150°C. This H-grade qualification ensures reliable operation in under-hood automotive locations, industrial enclosures, and avionics bays where ambient temperatures exceed 105°C. Thermal derating applies above 125°C per datasheet Note 2.
Does LT3973HMSE-3.3#TRPBF require external feedback resistors?
No, LT3973HMSE-3.3#TRPBF does not require external feedback resistors. As a fixed 3.3V variant, it internally connects the VOUT pin (Pin 1) to a precision resistor divider-eliminating two external components and associated layout sensitivity while maintaining ±1.2% output accuracy over temperature.
How does LT3973HMSE-3.3#TRPBF maintain regulation during automotive cold-crank?
LT3973HMSE-3.3#TRPBF maintains regulation down to 3.83V input (for 3.3V output) using three coordinated mechanisms: enforced 530mV minimum dropout voltage, extended duty cycle up to ~97.5% via BOOST capacitor charge management, and low 2.5µA quiescent current that minimizes voltage drop across input ESR during deep discharge.
What is the purpose of the BD pin on LT3973HMSE-3.3#TRPBF?
The BD (Bias Diode) pin on LT3973HMSE-3.3#TRPBF accepts an external bias voltage >3.2V-typically sourced from the regulated 3.3V output-to power the internal control circuitry. This reduces current drawn from VIN, improving full-load efficiency by up to 2% and lowering thermal stress on the input path.
Can LT3973HMSE-3.3#TRPBF be used with input voltages below 4.2V?
LT3973HMSE-3.3#TRPBF begins switching below 4.2V (down to ~3V), but regulation degrades as the internal 1.21V reference becomes inaccurate. For reliable 3.3V output, VIN must remain ≥4.2V per datasheet specifications; operation below this threshold is only suitable for non-regulated pre-bias or auxiliary functions-not for powering sensitive digital loads.
LT3973HMSE-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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LT3973HMSE-3.3#TRPBF FAQ
1.How can I place an order for LT3973HMSE-3.3#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973HMSE-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 LT3973HMSE-3.3#TRPBF reliable?
The price and inventory of LT3973HMSE-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 LT3973HMSE-3.3#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3973HMSE-3.3#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973HMSE-3.3#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973HMSE-3.3#TRPBF?
LT3973HMSE-3.3#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973HMSE-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 LT3973HMSE-3.3#TRPBF?
For technical support, including LT3973HMSE-3.3#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973HMSE-3.3#TRPBF requirements.
6.How does Aetrix verify that LT3973HMSE-3.3#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3973HMSE-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 LT3973HMSE-3.3#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3973HMSE-3.3#TRPBF?
All LT3973HMSE-3.3#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973HMSE-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 LT3973HMSE-3.3#TRPBF part is unused and in its original packaging.
Return procedure for LT3973HMSE-3.3#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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