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Analog Devices Inc. LT3971EMSE#TRPBF
- Part No.:
- LT3971EMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3971EMSE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 1.2A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:402
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Product details
Overview
LT3971EMSE#TRPBF from Analog Devices (formerly Linear Technology) is a 38V, 1.2A monolithic synchronous step-down 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 via RT pin, and integrates a 0.33Ω bipolar NPN switch, boost Schottky diode, and power-good flag. It is used in automotive battery regulation and portable power supplies where low standby power and wide VIN range are critical.
For engineers reviewing the LT3971EMSE#TRPBF datasheet, LT3971EMSE#TRPBF pinout, LT3971EMSE#TRPBF application, or LT3971EMSE#TRPBF equivalent, key selection criteria include its 4.3V–38V input range, 1.19V–30V programmable output, 91% PG threshold accuracy, internal compensation, and Burst Mode operation maintaining <15mVP-P ripple at light loads.
Technical Context
The LT3971EMSE#TRPBF employs constant-frequency current-mode control with internal slope compensation for fast transient response and loop stability. Its oscillator is RT-programmable (200kHz–2MHz), and it features frequency foldback during startup/overload to limit inrush current.
It uses an internally compensated error amplifier regulating FB to 1.19V (or fixed 3.3V/5V on variant parts), with soft-start controlled by external SS capacitor. The BOOST pin drives the internal bipolar switch via external capacitor, enabling full saturation across input range up to 38V.
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. |
| Quiescent Current | 2.8µA at no load - enables >10-year battery life in always-on IoT sensors and telematics modules. |
| Max Output Current | 1.2A continuous - sufficient for powering microcontrollers, CAN transceivers, and analog front-ends in compact designs. |
| Switching Frequency | 200kHz to 2MHz (RT-programmable) - allows tradeoff between small magnetics (high fSW) and high efficiency at light loads (low fSW). |
| Feedback Voltage | 1.19V ±1.3% (–40°C to 125°C) - enables precise output programming from 1.19V to 30V using external resistor divider. |
| Power Good Threshold | 91% of regulated VOUT with 100mV hysteresis - provides reliable system reset signaling without external monitoring circuitry. |
| Shutdown Current | 700nA - ensures minimal battery drain when disabled in sleep-mode systems. |
Pinout & Package
LT3971EMSE#TRPBF is housed in a 10-lead plastic MSOP package (3mm × 3mm footprint) with exposed thermal pad (Pin 11 = GND) for low θJA = 45°C/W. The package is RoHS-compliant and rated for –40°C to 125°C junction temperature.
| 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 3) | Bootstrap Drive Voltage | Provides >VIN voltage to fully saturate internal bipolar NPN switch; requires external capacitor to SW. |
| SW (Pin 5) | Switch Node | Drives external inductor and catch diode; carries high di/dt switching current - requires tight layout. |
| VIN (Pin 7) | Main Input Supply | Supplies internal circuitry and switch; must be locally bypassed with low-ESR ceramic capacitor. |
| EN (Pin 8) | Enable Control | Hysteretic 1.005V rising / 0.975V falling threshold; pulls device into 700nA shutdown when low. |
| FB (Pin 9) | Feedback Input | Regulated to 1.19V; connects to resistor divider tap - determines output voltage in adjustable configuration. |
| SS (Pin 12) | Soft-Start Control | External capacitor ramps peak current limit at startup; prevents inrush into large output capacitors. |
| RT (Pin 13) | Frequency Set | Resistor to GND sets switching frequency from 200kHz to 2MHz; defines minimum on/off times. |
| PG (Pin 14) | Power Good Flag | Open-drain output active-low until VOUT reaches 91% of target; requires external pull-up. |
| GND (Pin 16 + Exposed Pad) | Ground Reference | Primary return path for power and signal; exposed pad must be soldered to PCB for thermal performance. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow Quiescent Current | 2.8µA IQ in regulation enables multi-year operation from coin cells in remote sensors and asset trackers. |
| Low Ripple Burst Mode | Maintains <15mVP-P output ripple while delivering single current pulses at light loads - avoids audible noise and EMI spikes. |
| Internal Compensation | Eliminates need for external compensation network - reduces BOM count and design iteration time for standard applications. |
| Accurate Power Good Flag | 91% VOUT threshold with 100mV hysteresis ensures deterministic system power sequencing without external comparators. |
| Thermally Enhanced Package | 10-lead MSOP with exposed GND pad achieves θJA = 45°C/W - supports 1.2A output in compact space-constrained layouts. |
Applications
| Automotive Body Control Module | Industrial Sensor Node |
|---|---|
Use Scenario: Powering MCU, LIN transceiver, and analog sensor interface from 12V battery with cold-crank tolerance down to 4.5V. IC Role / Device Role / Timing Role: Primary 3.3V buck regulator providing stable supply under wide input transients and ultra-low sleep current. Use Value: 2.8µA quiescent current extends battery life beyond 10 years in parked vehicle mode; 38V rating withstands load-dump surges. |
Use Scenario: Long-life wireless vibration sensor powered by primary lithium thionyl chloride cell (3.6V nominal, 30+ year shelf life). IC Role / Device Role / Timing Role: Step-down regulator converting 3.6V–30V input (from energy harvester or stacked cells) to regulated 3.3V for RF SoC and ADC. Use Value: Internal 10MΩ feedback divider minimizes load current; 700nA shutdown current preserves cell capacity during extended sleep intervals. |
| Portable Medical Monitor | Smart Building Controller |
Use Scenario: Battery-powered ECG front-end requiring clean, low-noise 5V rail for precision op-amps and ADC drivers. IC Role / Device Role / Timing Role: Fixed 5V output buck converter (LT3971-5 variant compatible) with soft-start and PG flag for safe power-up sequencing. Use Value: Low ripple Burst Mode eliminates switching noise coupling into sensitive analog signal paths - improves SNR by >15dB vs. standard PWM. |
Use Scenario: DIN-rail mounted HVAC controller drawing power from 24V DC industrial bus with strict EMC requirements. IC Role / Device Role / Timing Role: Main 3.3V supply for ARM Cortex-M7 MCU, Ethernet PHY, and isolated RS-485 transceivers. Use Value: RT-programmable 800kHz switching frequency balances EMI filtering cost and inductor size; SYNC pin enables clock synchronization to avoid beat frequencies. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EMSE#TRPBF | 42V input, 3.5A output, 2.5µA IQ, Silent Switcher architecture - lower EMI but larger package (16-lead MSE). | Required where CISPR-25 Class 5 EMI compliance is mandatory (e.g., automotive infotainment). | Select LT8610EMSE#TRPBF only if EMI reduction outweighs cost and board area increase; not drop-in due to different pinout and layout rules. |
| TPS54202DRCT | 28V input, 2A output, 26µA IQ, integrated MOSFETs - higher IQ, smaller solution size, no BOOST pin. | Suitable for cost-sensitive industrial applications where 26µA IQ is acceptable and input stays ≤24V. | Choose TPS54202DRCT for simpler design and lower BOM cost when ultralow IQ is not required and input voltage is limited. |
Compared with LT3971EMSE#TRPBF, LT8610EMSE#TRPBF offers superior EMI performance but requires redesign for layout and thermal management, while TPS54202DRCT trades 10× higher quiescent current for lower system cost and smaller footprint - making LT3971EMSE#TRPBF optimal for battery longevity and wide-input ruggedness.
Availability
LT3971EMSE#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, portable medical monitors, industrial sensor nodes, and smart building controllers requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3971EMSE#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, documentation, and manufacturing continuity for the LT3971 family.
The LT3971 series was designed specifically for high-reliability, wide-input DC/DC conversion in automotive, industrial, and portable applications demanding ultralow quiescent current and robust fault tolerance.
FAQ
What is the maximum input voltage supported by the LT3971EMSE#TRPBF?
The LT3971EMSE#TRPBF supports an absolute maximum input voltage of 38V on the VIN pin. For reliable continuous operation, the maximum operating input voltage depends on switching frequency and output voltage - for example, at 2MHz and 3.3V output, VIN(OP-MAX) ≈ 24V; at 200kHz, it extends to ~36V. Transient overvoltage up to 38V is tolerated but may trigger pulse-skipping mode.
Does the LT3971EMSE#TRPBF require an external catch diode?
No, the LT3971EMSE#TRPBF integrates a boost Schottky diode and does not require an external catch diode. The BD pin connects to the anode of the internal Schottky, and the BOOST pin provides the gate drive voltage for the internal bipolar NPN switch - eliminating the need for external diode or MOSFET in standard buck configurations.
Can the LT3971EMSE#TRPBF be synchronized to an external clock?
Yes, the LT3971EMSE#TRPBF supports external synchronization via the SYNC pin (Pin 15). When driven by a clock source between 250kHz and 2MHz, it synchronizes switching and enters pulse-skipping mode at light loads - increasing quiescent current to 1.5mA. For lowest IQ, ground SYNC to enable low-ripple Burst Mode instead.
What is the purpose of the SS pin on the LT3971EMSE#TRPBF?
The SS (soft-start) pin on the LT3971EMSE#TRPBF controls inrush current during startup by ramping the internal peak current limit. A capacitor from SS to GND sets the soft-start time - typical values are 1nF to 10nF. The SS pin is released when EN goes high; it is actively discharged only during shutdown, preventing output overshoot in hot-plug scenarios.
How does the LT3971EMSE#TRPBF achieve 2.8µA quiescent current?
The LT3971EMSE#TRPBF achieves 2.8µA quiescent current through low-power circuit design, including optimized biasing of internal amplifiers and logic, and Burst Mode operation that shuts down most circuitry between switching pulses. This occurs only when SYNC is grounded; synchronizing to an external clock raises IQ to 1.5mA due to continuous oscillator operation.
LT3971EMSE#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):
- 4.3V
- 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#TRPBF FAQ
1.How can I place an order for LT3971EMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3971EMSE#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 LT3971EMSE#TRPBF reliable?
The price and inventory of LT3971EMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3971EMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3971EMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3971EMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3971EMSE#TRPBF?
LT3971EMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3971EMSE#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 LT3971EMSE#TRPBF?
For technical support, including LT3971EMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3971EMSE#TRPBF requirements.
6.How does Aetrix verify that LT3971EMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3971EMSE#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 LT3971EMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3971EMSE#TRPBF?
All LT3971EMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3971EMSE#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 LT3971EMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3971EMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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