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Analog Devices Inc. LT3971EMSE#PBF
- Part No.:
- LT3971EMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3971EMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1.2A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:569
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Product details
Overview
LT3971EMSE#PBF from Analog Devices (formerly Linear Technology) is a 38V, 1.2A monolithic synchronous step-down DC/DC regulator in a thermally enhanced 10-lead MSOP package. It delivers ultralow 2.8µA quiescent current in regulation, supports adjustable switching frequency from 200kHz to 2MHz, and features internal compensation, power good flag, and soft-start. It is designed for automotive battery regulation and portable industrial power supplies where low standby power and wide input range are critical.
For engineers reviewing the LT3971EMSE#PBF datasheet, LT3971EMSE#PBF pinout, LT3971EMSE#PBF application, or LT3971EMSE#PBF equivalent, key selection criteria include its 4.3V–38V input range, 1.19V–30V programmable output, 1.2A output capability, Burst Mode® operation with <15mV ripple, and 10-lead MSOP thermal performance.
Technical Context
The LT3971EMSE#PBF implements constant-frequency current-mode control with an internal 0.33Ω bipolar NPN switch and integrated boost Schottky diode driver. Its oscillator is resistor-programmable via the RT pin and synchronizable externally through the SYNC pin (250kHz–2MHz range).
It uses an internally compensated error amplifier referenced to a precise 1.19V FB threshold, with fast transient response enabled by current-mode topology. The device enters low-ripple Burst Mode® at light loads-reducing quiescent current to 1.7µA-and provides accurate enable (1.01V threshold) and power good (91% VOUT trip) functions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.3V to 38V - supports direct connection to 12V/24V automotive batteries and industrial rails without pre-regulation. |
| Output Current | 1.2A maximum - sufficient for powering microcontrollers, sensors, and interface ICs in compact systems. |
| Quiescent Current | 2.8µA at no load - enables multi-year battery life in always-on IoT and telematics applications. |
| Switching Frequency | 200kHz to 2MHz - adjustable via RT resistor; higher frequencies allow smaller magnetics and capacitors. |
| Feedback Reference | 1.19V ±1.3% - high-accuracy reference enabling tight output voltage regulation across temperature. |
| Power Good Threshold | 91% of regulated output - open-drain PG signal confirms stable rail before system initialization. |
| Shutdown Current | 700nA - near-zero leakage during deep sleep, critical for energy-harvesting and backup power designs. |
Pinout & Package
LT3971EMSE#PBF is housed in a 10-lead plastic MSOP package (3mm × 3mm footprint) with exposed pad (Pin 11) soldered to PCB for low thermal resistance (θJA = 45°C/W). The package supports high-power density while maintaining compatibility with standard surface-mount assembly processes.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (Pin 1) | Boost Diode Anode Connection | Connects to cathode of external Schottky diode; forms bootstrap path for switch drive. |
| BOOST (Pin 2) | Bootstrap Drive Voltage Input | Provides >VIN voltage to fully saturate internal NPN switch; requires external capacitor to SW. |
| SW (Pin 3) | Switch Node Output | Drives external inductor and catch diode; high dv/dt node requiring careful layout and grounding. |
| VIN (Pin 4) | Main Power Input | Supplies internal circuitry and switch; must be locally bypassed with low-ESR ceramic capacitor. |
| EN (Pin 5) | Enable Control Input | Hysteretic 1.01V rising threshold enables shutdown with 700nA supply current when pulled low. |
| FB (Pin 6) | Feedback Voltage Sense | Regulated to 1.19V; connects to resistor divider tap for adjustable output voltage configuration. |
| SS (Pin 7) | Soft-Start Control | Capacitor-to-ground ramps peak current limit at startup; prevents inrush into large output caps. |
| RT (Pin 8) | Frequency Set Resistor | Resistor-to-ground sets switching frequency from 200kHz to 2MHz per manufacturer table. |
| PG (Pin 9) | Power Good Flag | Open-drain output signals valid regulation when FB reaches 91% of target voltage. |
| SYNC (Pin 10) | External Clock Input | Ground for Burst Mode; tie to external clock (250kHz–2MHz) for synchronized 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. |
| Low-Ripple Burst Mode® | Maintains <15mVP-P output ripple at light loads while preserving high efficiency. |
| Internal Compensation | Eliminates external compensation components-reduces BOM count and design iteration time. |
| Accurate Enable Threshold | 1.01V EN rising threshold with 30mV hysteresis ensures reliable power sequencing. |
| Thermally Enhanced Package | 10-lead MSOP with exposed GND pad achieves θJA = 45°C/W for 1.2A continuous operation. |
Applications
| Automotive Battery Regulation | Portable Industrial Sensors |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery to 3.3V/5V for CAN transceivers, MCU, and memory in ADAS modules. IC Role / Device Role / Timing Role: Primary buck converter delivering stable, low-noise power under cold-crank (4.3V) and load-dump (38V) conditions. Use Value: 2.8µA quiescent current prevents battery drain during extended parking; Burst Mode maintains <15mV ripple during sleep states. | Use Scenario: Powering wireless sensor nodes deployed in remote industrial environments with primary Li-SOCl₂ or AA batteries. IC Role / Device Role / Timing Role: High-efficiency step-down regulator enabling multi-year operation without maintenance. Use Value: 700nA shutdown current and programmable soft-start minimize wake-up transients and extend usable battery capacity. |
| Industrial Programmable Logic Controllers | Railway Signaling Systems |
Use Scenario: Converting 24V DC field bus to 5V for FPGA I/O banks and communication interfaces in modular PLC backplanes. IC Role / Device Role / Timing Role: Robust, wide-input buck regulator supporting hot-swap and brown-out resilience. Use Value: 38V absolute max rating and 4.3V minimum start-up voltage ensure reliable operation across varying rail conditions. | Use Scenario: Providing isolated 3.3V logic supply from 72V–110V nominal railway traction battery in signaling controllers. IC Role / Device Role / Timing Role: Pre-regulator stage stepping down high-voltage rail to intermediate level for downstream converters. Use Value: Adjustable frequency allows optimization for EMI compliance in safety-critical rail EMC environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5164QDDARQ1 | 4.5V–65V input, 1A output, 1.5µA IQ, requires external compensation | Better suited for ultra-high VIN (>40V) automotive front-end regulation | Select LM5164QDDARQ1 when input exceeds 38V or when AEC-Q100 Grade 1 qualification is mandatory. |
| TPS54202DRCT | 4.5V–28V input, 2A output, 2µA IQ, integrated MOSFETs, no BOOST pin | Optimized for cost-sensitive, lower-VIN consumer and industrial applications | Choose TPS54202DRCT when operating below 28V and board space is constrained by need for fewer passives. |
Compared with LM5164QDDARQ1 and TPS54202DRCT, the LT3971EMSE#PBF uniquely balances 38V max input, 1.2A output, 2.8µA IQ, and integrated boost diode drive-making it optimal for mid-range industrial and automotive subsystems requiring both robustness and ultra-low standby power.
Availability
LT3971EMSE#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, portable industrial sensors, and industrial programmable logic controllers requiring stable component supply with long-term lifecycle support.
Supply support for LT3971EMSE#PBF 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, documentation, and manufacturing continuity for the LT3971 family.
The LT3971 product line was engineered for high-reliability, wide-input DC/DC conversion in automotive, industrial, and avionics systems where ultralow quiescent current and fault-tolerant operation are essential.
FAQ
What is the minimum input voltage required for LT3971EMSE#PBF to regulate a 3.3V output?
The LT3971EMSE#PBF requires a minimum input voltage of 4.3V to maintain accurate feedback regulation at any output voltage, including 3.3V. Below this threshold, the internal reference and control circuitry cannot sustain regulation-verified across –40°C to 125°C junction temperature. For reliable start-up under cold-crank conditions, ensure VIN remains ≥4.3V during all operational phases.
Does LT3971EMSE#PBF support fixed-output variants like 3.3V or 5V?
No-LT3971EMSE#PBF is the adjustable version of the family and requires an external resistor divider on the FB pin to set output voltage between 1.19V and 30V. Fixed-output variants (e.g., LT3971EMSE-3.3#PBF) integrate the 10MΩ feedback network internally; LT3971EMSE#PBF does not contain those resistors and must be configured externally.
How is Burst Mode® operation enabled on LT3971EMSE#PBF?
Burst Mode® is enabled automatically when the SYNC pin is grounded-no additional configuration required. In this mode, the LT3971EMSE#PBF delivers discrete current pulses to the output capacitor followed by sleep periods, achieving 2.8µA quiescent current. If SYNC is tied to an external clock, the device switches to pulse-skipping mode (IQ ≈ 1.5mA), disabling Burst Mode®.
What thermal considerations apply to LT3971EMSE#PBF in a 1.2A application?
At 1.2A continuous load and 12V input → 3.3V output, LT3971EMSE#PBF dissipates ~1.1W. With its 10-lead MSOP package (θJA = 45°C/W) and properly soldered exposed pad, junction temperature rise is ~50°C above ambient-well within the –40°C to 125°C operating range. Thermal relief vias under the pad and ≥1in² copper pour are recommended for sustained full-load operation.
Can LT3971EMSE#PBF be synchronized to an external clock, and what is the supported frequency range?
Yes-LT3971EMSE#PBF supports external synchronization via the SYNC pin over 250kHz to 2MHz. When driven by a clean CMOS-level clock, the internal oscillator locks to the external source, enabling EMI reduction through frequency dithering or alignment with system clocks. Synchronization disables Burst Mode® and increases light-load IQ to ~1.5mA due to active pulse-skipping.
LT3971EMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.3V
- Voltage - Input (Max):
- 38V
- Voltage - Output (Min/Fixed):
- 1.19V
- Voltage - Output (Max):
- 30V
- 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
LT3971EMSE#PBF FAQ
1.How can I place an order for LT3971EMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3971EMSE#PBF 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 LT3971EMSE#PBF reliable?
The price and inventory of LT3971EMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3971EMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3971EMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3971EMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3971EMSE#PBF?
LT3971EMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3971EMSE#PBF 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 LT3971EMSE#PBF?
For technical support, including LT3971EMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3971EMSE#PBF requirements.
6.How does Aetrix verify that LT3971EMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3971EMSE#PBF 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 LT3971EMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3971EMSE#PBF?
All LT3971EMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3971EMSE#PBF, 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 LT3971EMSE#PBF part is unused and in its original packaging.
Return procedure for LT3971EMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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