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Analog Devices Inc. LT3971IMSE-3.3#TRPBF
- Part No.:
- LT3971IMSE-3.3#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3971IMSE-3.3#TRPBF.pdf
- Description:
- IC REG BUCK 3.3V 1.2A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,384
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Product details
Overview
LT3971IMSE-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-output 3.3V, 1.2A monolithic buck switching regulator in a 10-lead MSOP package with exposed pad. It operates from 4.3V to 38V input, delivers ultralow 2.8µA quiescent current in regulation, and uses low-ripple Burst Mode® for high light-load efficiency in automotive battery and portable power applications.
For engineers reviewing the LT3971IMSE-3.3#TRPBF datasheet, LT3971IMSE-3.3#TRPBF pinout, LT3971IMSE-3.3#TRPBF application, or LT3971IMSE-3.3#TRPBF equivalent, key selection criteria include its 3.3V fixed output accuracy (±1.5%), 2.8µA no-load IQ, 1.2A output capability, 4.3–38V wide VIN range, and integrated boost Schottky diode with 770mV forward drop at 100mA.
Technical Context
The LT3971IMSE-3.3#TRPBF implements constant-frequency current-mode control with internal compensation and an integrated 0.33Ω bipolar NPN switch. Its feedback loop regulates the VOUT pin directly to 3.3V using an internal 10MΩ resistor divider, eliminating external resistors.
Burst Mode® operation reduces input supply current to 1.7µA during sleep cycles while maintaining output ripple below 15mVP-P; frequency foldback during startup and overload prevents excessive peak currents. The device features a 1V enable threshold with 30mV hysteresis and an open-drain power good (PG) flag that asserts when VOUT reaches 91% of nominal.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.5% over –40°C to 125°C; eliminates need for external feedback resistors. |
| Input Voltage Range | 4.3V to 38V; supports 12V/24V automotive batteries and industrial DC rails without pre-regulation. |
| Max Output Current | 1.2A continuous; sufficient for powering microcontrollers, sensors, and communication ICs. |
| Quiescent Current | 2.8µA at no load (12VIN → 3.3VOUT); enables multi-year battery life in always-on IoT nodes. |
| Switching Frequency | Adjustable 200kHz–2MHz via RT pin; 800kHz typical in reference design for optimal size/efficiency tradeoff. |
| Power Good Flag | Open-drain PG asserts when VOUT ≥ 91% of 3.3V (≥3.003V); provides system-level power sequencing and fault detection. |
| Shutdown Current | 700nA with EN low; ensures near-zero drain during deep sleep or standby modes. |
Pinout & Package
LT3971IMSE-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 for low θJA = 45°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (Pin 1) | Boost Diode Anode | Connects to cathode of external Schottky diode; forms bootstrap path for high-side drive. |
| BOOST (Pin 2) | Bootstrap Drive Voltage | Provides >VIN voltage to fully saturate internal NPN switch; requires external capacitor to VOUT. |
| SW (Pin 3) | Switch Node | Drives external inductor and catch diode; carries high dI/dt switching current. |
| VIN (Pin 4) | Main Input Supply | Supplies internal circuitry and switch; must be locally bypassed with low-ESR ceramic capacitor. |
| EN (Pin 5) | Enable Control | Hysteretic 1.005V rising / 0.975V falling threshold; pulls to GND for shutdown (700nA IQ). |
| VOUT (Pin 6) | Fixed Output Sense | Internally regulated to 3.3V; connects to output capacitor and load; replaces FB pin in adjustable variants. |
| SS (Pin 7) | Soft-Start Control | External capacitor ramps peak current limit at startup; prevents inrush into large output caps. |
| RT (Pin 8) | Frequency Set | Resistor to GND programs switching frequency from 200kHz to 2MHz (e.g., 49.9kΩ = 800kHz). |
| PG (Pin 9) | Power Good Flag | Open-drain output pulled high externally; signals valid regulation (VOUT ≥ 3.003V). |
| SYNC (Pin 10) | Clock Synchronization | Ground for Burst Mode; tie to external clock (250kHz–2MHz) for forced PWM/pulse-skipping. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow Quiescent Current | 2.8µA IQ in regulation enables >10-year battery life in always-on sensor nodes powered by coin cells or Li-SOCl₂. |
| Low-Ripple Burst Mode® | Maintains <15mVP-P output ripple at light loads while sustaining >85% efficiency down to 100µA output current. |
| Integrated Boost Schottky | On-die Schottky diode with 770mV VF at 100mA reduces BOM count and improves thermal performance vs. discrete solutions. |
| Internal Feedback Divider | 10MΩ resistor network sets precise 3.3V output; eliminates external resistors and associated leakage paths that degrade light-load IQ. |
| Thermally Enhanced Package | 10-lead MSOP with exposed pad achieves θJC = 10°C/W; supports 1.2A continuous output without heatsink in compact layouts. |
Applications
| Automotive Body Control Module | Portable Medical Sensor Hub |
|---|---|
Use Scenario: Powering CAN transceivers, door lock actuators, and interior lighting controllers from 12V battery with cold-crank tolerance. IC Role / Device Role / Timing Role: Primary 3.3V system rail regulator delivering stable voltage across 4.3–38V input transients including load dump. Use Value: 2.8µA quiescent current minimizes parasitic drain during vehicle off-state, extending battery life beyond ISO 16750-2 requirements. | Use Scenario: Supplying ultra-low-power ECG front-end, BLE SoC, and display driver in wearable patch monitors. IC Role / Device Role / Timing Role: Main power converter for battery-powered medical devices requiring long shelf life and reliable startup at low temperatures. Use Value: Internal 10MΩ feedback divider and 700nA shutdown current enable >5-year shelf life on primary lithium batteries. |
| Industrial IoT Gateway | Railway Onboard Telematics Unit |
Use Scenario: Providing 3.3V rail for ARM Cortex-M7 MCU, RS-485 transceivers, and LoRaWAN radio in edge gateways deployed in remote substations. IC Role / Device Role / Timing Role: High-reliability DC-DC converter operating continuously across –40°C to 125°C junction temperature range. Use Value: Guaranteed 1.2A output and 38V max input withstand sustained surges per IEC 61000-4-5, reducing need for upstream TVS protection. | Use Scenario: Powering GPS/GNSS receivers, cellular modems, and vibration sensors in train-mounted condition monitoring systems. IC Role / Device Role / Timing Role: Input-tolerant step-down regulator handling EN 50155-compliant 24V/72V/110V nominal rail variations and transients. Use Value: 4.3V minimum input enables reliable startup after brownouts; PG flag synchronizes firmware boot sequence with stable 3.3V rail. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3630EMSE-3.3#PBF | Same 10-lead MSOP package, 3.3V fixed output, but higher 10µA IQ and no integrated boost diode. | Requires external Schottky diode; less suitable for space-constrained designs where board area is critical. | Select when lower cost outweighs need for integrated diode and ultralow IQ. |
| TPS62130ARGTR | 3.3V fixed, 3A output, 17µA IQ, 3–17V input; uses synchronous rectification instead of external diode. | Higher output current and wider input range, but lacks 38V rating and automotive temperature grade. | Select for consumer-grade applications needing higher current and smaller solution size with sync FET. |
Compared with LTC3630EMSE-3.3#PBF and TPS62130ARGTR, LT3971IMSE-3.3#TRPBF uniquely combines 38V input tolerance, –40°C to 125°C operation, integrated boost diode, and 2.8µA IQ-making it optimal for automotive and industrial environments where input surge resilience and battery longevity are paramount.
Availability
LT3971IMSE-3.3#TRPBF is available at Aetrix Electronics and suitable for automotive body electronics, portable medical instrumentation, and industrial IoT gateways requiring stable component supply across extended temperature and long product lifecycles.
Supply support for LT3971IMSE-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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, formed through the acquisition of Linear Technology in 2017.
The LT3971 family was designed specifically for high-input-voltage, ultralow-quiescent-current DC-DC conversion in automotive, industrial, and battery-powered systems where reliability across extreme temperatures and minimal standby power are essential.
FAQ
What is the guaranteed output voltage accuracy of the LT3971IMSE-3.3#TRPBF over temperature?
The LT3971IMSE-3.3#TRPBF guarantees a 3.3V output with ±1.5% tolerance over the full –40°C to 125°C junction temperature range, as confirmed by electrical characteristics tables specifying 3.25V to 3.35V min/max at temperature extremes. This accuracy is achieved using an internal precision 10MΩ feedback divider and trimmed bandgap reference, eliminating drift from external resistor tolerances.
Can the LT3971IMSE-3.3#TRPBF operate with input voltages below 4.3V?
No-the LT3971IMSE-3.3#TRPBF requires a minimum input voltage of 4.3V to maintain regulation, as specified in Absolute Maximum Ratings and Electrical Characteristics. Below this threshold, the device cannot sustain 3.3V output due to insufficient headroom for the internal switch and control circuitry; attempting operation risks unregulated output or dropout.
How does the LT3971IMSE-3.3#TRPBF achieve 2.8µA quiescent current while regulating?
The LT3971IMSE-3.3#TRPBF achieves 2.8µA quiescent current through low-ripple Burst Mode® operation: it delivers discrete current pulses to the output capacitor, then enters deep sleep between bursts-shutting down oscillator, error amplifier, and gate drivers. During sleep, only essential bias circuits remain active, drawing just 1.7µA, while the average IQ reaches 2.8µA under no-load conditions.
Is an external Schottky diode required when using the LT3971IMSE-3.3#TRPBF?
No-an external Schottky diode is not required because the LT3971IMSE-3.3#TRPBF integrates a boost Schottky diode on-die (connected to BD pin), which forms the bootstrap path for the internal NPN switch. However, an external catch diode (e.g., DFLS2100) is still required between SW and VOUT to complete the buck power path.
What is the function of the SS pin on the LT3971IMSE-3.3#TRPBF, and how is it used?
The SS (soft-start) pin on the LT3971IMSE-3.3#TRPBF controls inrush current by ramping the internal peak current limit during startup. A capacitor from SS to GND (e.g., 1nF) creates a linear voltage ramp; the device begins switching only after SS reaches ~1V. Floating SS disables soft-start, while grounding SS forces immediate full-current startup-useful for fast-response applications where controlled ramp is unnecessary.
LT3971IMSE-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):
- 4.3V
- Voltage - Input (Max):
- 38V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 1.2A
- Frequency - Switching:
- 200kHz ~ 2MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LT3971IMSE-3.3#TRPBF FAQ
1.How can I place an order for LT3971IMSE-3.3#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3971IMSE-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 LT3971IMSE-3.3#TRPBF reliable?
The price and inventory of LT3971IMSE-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 LT3971IMSE-3.3#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3971IMSE-3.3#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3971IMSE-3.3#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3971IMSE-3.3#TRPBF?
LT3971IMSE-3.3#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3971IMSE-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 LT3971IMSE-3.3#TRPBF?
For technical support, including LT3971IMSE-3.3#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3971IMSE-3.3#TRPBF requirements.
6.How does Aetrix verify that LT3971IMSE-3.3#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3971IMSE-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 LT3971IMSE-3.3#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3971IMSE-3.3#TRPBF?
All LT3971IMSE-3.3#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3971IMSE-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 LT3971IMSE-3.3#TRPBF part is unused and in its original packaging.
Return procedure for LT3971IMSE-3.3#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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