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Analog Devices Inc. LT3973EMSE#TRPBF
- Part No.:
- LT3973EMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3973EMSE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 750MA 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:600
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Product details
Overview
LT3973EMSE#TRPBF from Analog Devices (formerly Linear Technology) is a 42V, 750mA monolithic step-down DC/DC regulator with integrated power switch, catch diode, and boost diode. It delivers fixed 5V output, operates down to 4.2V input, maintains 530mV minimum dropout, and achieves 2.5µA quiescent current at 12VIN–5VOUT. It is used in automotive cold-crank battery regulation where ultra-low IQ and robust dropout performance are critical.
For engineers reviewing the LT3973EMSE#TRPBF datasheet, LT3973EMSE#TRPBF pinout, LT3973EMSE#TRPBF application, or LT3973EMSE#TRPBF equivalent, key selection criteria include its 5V fixed output, 10-lead MSOP package with exposed pad, 200kHz–2.2MHz programmable switching frequency, low-ripple Burst Mode™ operation (<10mVP-P), and accurate power-good flag signaling at 90% VOUT.
Technical Context
The LT3973EMSE#TRPBF implements constant-frequency current-mode control with internal bipolar NPN switch and integrated Schottky diodes for boost and catch functions. Its architecture supports extended duty cycle up to ~97.5% via boost capacitor charge management, enabling stable regulation during automotive cold-crank when VIN approaches VOUT.
It features dual current limiting: peak switch current limit (1.65A typ) and valley catch diode current limit (1.15A typ), plus thermal shutdown, programmable EN/UVLO (1.19V threshold), and a dedicated open-drain power-good (PG) output that asserts when FB reaches 90% of 1.21V reference.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5V ±1.2% over –40°C to 125°C; enables direct replacement of LDOs in 5V rail generation without external feedback resistors. |
| Input Voltage Range | 4.2V to 42V; supports wide automotive battery range including cold-crank (down to ~4.2V) and load-dump transients (up to 42V). |
| Quiescent Current | 2.5µA at 12VIN–5VOUT; ensures >1-year battery life in always-on automotive modules with 20mAh coin cell. |
| Switching Frequency | 200kHz to 2.2MHz (RT-programmable); allows optimization between EMI compliance (lower fSW) and compact solution size (higher fSW). |
| Output Current | 750mA continuous; sufficient for powering microcontrollers, CAN transceivers, and sensor interfaces in space-constrained modules. |
| Dropout Voltage | 530mV minimum; guarantees regulation when VIN drops to VOUT + 530mV - critical for engine start-up in 12V systems. |
| Power Good Flag | Open-drain PG output asserts high when VOUT ≥ 4.5V (90% of 5V); provides system-level power sequencing and fault detection without external comparators. |
Pinout & Package
LT3973EMSE#TRPBF is housed in a thermally enhanced 10-lead plastic MSOP package with exposed pad (Pin 11 = GND), θJA = 45°C/W. The exposed pad must be soldered to PCB for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB/VOUT (Pin 1) | Feedback input / Fixed-output sense | For LT3973EMSE#TRPBF (5V variant), this pin connects internally to the fixed 5V divider; no external resistor network required. |
| OUT (Pin 2) | Output voltage sensing node | Internally tied to regulated 5V output; used for dropout comparator and boost capacitor charging control. |
| EN/UVLO (Pin 3) | Enable and undervoltage lockout input | Active-high enable with 1.19V rising threshold and 30mV hysteresis; supports programmable UVLO via external resistor divider. |
| VIN (Pin 4) | Main input power supply | Accepts 4.2V–42V; powers internal circuitry and switch driver; requires local 4.7µF ceramic bypass. |
| GND (Pin 5 & Pin 11) | Signal and power ground | Pin 5 is signal GND; Pin 11 is exposed thermal pad - both must connect to low-impedance PCB ground plane. |
| SW (Pin 6) | Switch node | Drives external inductor; carries high di/dt switching current; layout requires short, low-inductance path to minimize EMI. |
| BOOST (Pin 7) | Boost capacitor drive | Provides >VIN voltage to fully saturate internal bipolar NPN switch; requires 0.47µF ceramic capacitor to SW. |
| BD (Pin 8) | Boost diode anode connection | Connects to anode of external boost Schottky; also supplies bias current to internal regulator when BD > 3.2V. |
| PG (Pin 9) | Power good open-drain output | Sinks ≥220µA when active low; requires external pull-up to monitor 5V rail health in real time. |
| RT (Pin 10) | Frequency setting input | Resistor to GND sets switching frequency from 200kHz to 2.2MHz; determines inductor/capacitor sizing trade-offs. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost and catch Schottky diodes | Eliminates 2 external diodes, reduces BOM count and board area, and improves reliability by removing solder joint failure points. |
| Low-ripple Burst Mode™ operation | Maintains <10mVP-P output ripple at light loads while achieving 1.8µA no-load IQ - essential for noise-sensitive analog/sensor rails. |
| Accurate programmable undervoltage lockout | EN/UVLO threshold tolerance of ±30mV with 45mV hysteresis enables precise battery monitoring and controlled startup in automotive systems. |
| Thermal shutdown with automatic recovery | Protects against sustained overload or poor heatsinking; device resumes normal operation once junction temperature falls below safe threshold. |
| Minimum switch on-time of 70ns | Enables high VIN/VOUT ratios (e.g., 36V→5V) at higher frequencies without pulse-skipping instability or loss of regulation. |
Applications
| Automotive Body Control Module (BCM) | Industrial IoT Sensor Node |
|---|---|
Use Scenario: Powering microcontroller, LIN transceiver, and door-lock actuator drivers from vehicle battery under cold-crank (5.5V min) and stop-start cycling. IC Role / Device Role / Timing Role: Primary 5V buck regulator providing stable, low-noise supply with guaranteed regulation down to 5.83V input (5V + 530mV dropout). Use Value: Enables uninterrupted MCU operation during engine cranking without brownout resets or watchdog timeouts. |
Use Scenario: Battery-powered wireless temperature/humidity sensor operating in remote industrial facilities with 10-year deployment target. IC Role / Device Role / Timing Role: System power manager delivering 5V to RF SoC and analog front-end while minimizing standby current drain. Use Value: 2.5µA quiescent current extends 2000mAh LiSOCl₂ battery life beyond 10 years in sleep mode (10µA avg system load). |
| Portable Medical Diagnostic Device | Smart Building Occupancy Sensor |
Use Scenario: Handheld ultrasound probe requiring clean 5V rail for ADC, FPGA, and display backlight with minimal thermal rise during 5-minute scan sessions. IC Role / Device Role / Timing Role: High-efficiency 5V converter supporting burst-mode imaging loads up to 750mA with <10mV ripple. Use Value: Prevents image artifacts caused by power rail noise and avoids thermal throttling in sealed enclosure. |
Use Scenario: Ceiling-mounted PIR + ambient light sensor node powered by energy-harvesting solar cell and supercapacitor buffer. IC Role / Device Role / Timing Role: Low-IQ step-down regulator enabling reliable 5V startup from 4.5V supercap voltage during dawn/dusk transitions. Use Value: Guarantees functional startup even as supercap voltage decays from 5.2V to 4.5V - below typical LDO dropout limits. |
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 |
|---|---|---|---|
| LMR36520RNXR | 65V input, 2A output, 26µA IQ, adjustable output only; no fixed 5V option; uses MOSFET switch (no integrated diodes). | Requires external feedback resistors and catch diode; better suited for higher-current or wider-input designs where 5V is not fixed. | Select if >750mA load or >42V transient immunity is required; avoid if board space or BOM simplification is priority. |
| TPS6286518VRGTR | 6V input max, 4A output, 1.5µA IQ, fixed 5V output; integrates FETs but no diodes; uses D-CAP3 control. | Cannot support automotive battery inputs; limited to USB/industrial 5V bus applications; smaller 2mm × 2mm QFN package. | Select for compact, low-noise 5V point-of-load in non-automotive systems; unsuitable for 12V/24V battery-fed designs. |
Compared with LMR36520RNXR and TPS6286518VRGTR, the LT3973EMSE#TRPBF uniquely combines 42V input capability, fixed 5V output, integrated diodes, and sub-3µA IQ in a single 10-lead MSOP - making it optimal for space-constrained automotive and industrial 5V rail generation where simplicity and cold-crank resilience are mandatory.
Availability
LT3973EMSE#TRPBF is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor nodes, and portable medical diagnostics requiring stable component supply across extended temperature ranges (–40°C to 125°C) and long production lifecycles.
Supply support for LT3973EMSE#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 maintains full product support, datasheets, and application engineering for legacy Linear parts including the LT3973 family.
The LT3973 product line was designed specifically for high-reliability, ultra-low-quiescent-current DC/DC conversion in automotive and industrial environments where input voltage extremes and long-term stability are critical.
FAQ
What is the output voltage configuration of the LT3973EMSE#TRPBF?
The LT3973EMSE#TRPBF is the fixed 5V output variant of the LT3973 family. Its internal feedback divider is trimmed to regulate precisely to 5V ±1.2% across –40°C to 125°C. Unlike the base LT3973, it does not require external resistors on the FB pin - Pin 1 (labeled VOUT on the datasheet) connects directly to the internal 5V reference node. This simplifies design and improves accuracy versus resistor-based solutions.
Does the LT3973EMSE#TRPBF require external diodes?
No, the LT3973EMSE#TRPBF integrates both the catch Schottky diode and boost Schottky diode on-die. This eliminates two external components, reduces PCB footprint, and removes associated parasitic inductance and solder joint reliability risks. The integrated diodes are rated for 1.15A valley current (catch) and support full 750mA output capability without derating.
How does the LT3973EMSE#TRPBF maintain regulation during automotive cold-crank?
The LT3973EMSE#TRPBF maintains regulation down to VIN = VOUT + 530mV (i.e., 5.53V for 5V output) via its enforced minimum dropout voltage and extended duty cycle architecture. When VIN drops near VOUT, it increases on-time and reduces switching frequency while maintaining boost capacitor charge - enabling stable 5V output even during 5.5V battery dips typical of diesel engine cranking.
What is the purpose of the BD pin on the LT3973EMSE#TRPBF?
The BD (Boost Diode) pin on the LT3973EMSE#TRPBF serves two functions: (1) it connects to the anode of the external boost Schottky diode (required for generating the BOOST voltage), and (2) when biased above 3.2V - typically by connecting to the regulated 5V output - it powers the internal bias regulator, improving efficiency by reducing VIN current draw. This dual-role pin optimizes performance in both high- and low-input-voltage conditions.
Can the LT3973EMSE#TRPBF be synchronized to an external clock?
No, the LT3973EMSE#TRPBF does not support external clock synchronization. Its switching frequency is set solely by the RT-to-GND resistor and operates in free-running constant-frequency PWM mode. For applications requiring synchronization (e.g., multi-rail systems to avoid beat frequencies), designers must select alternatives such as the LT8610 or LTC3891, as the LT3973EMSE#TRPBF lacks an SYNC pin or phase-lock capability.
LT3973EMSE#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:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.2V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 1.21V
- Voltage - Output (Max):
- 24V
- 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
LT3973EMSE#TRPBF FAQ
1.How can I place an order for LT3973EMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973EMSE#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 LT3973EMSE#TRPBF reliable?
The price and inventory of LT3973EMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3973EMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3973EMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973EMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973EMSE#TRPBF?
LT3973EMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973EMSE#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 LT3973EMSE#TRPBF?
For technical support, including LT3973EMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973EMSE#TRPBF requirements.
6.How does Aetrix verify that LT3973EMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3973EMSE#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 LT3973EMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3973EMSE#TRPBF?
All LT3973EMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973EMSE#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 LT3973EMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3973EMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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