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Analog Devices Inc. LT3971IMSE#PBF
- Part No.:
- LT3971IMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3971IMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1.2A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,104
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Product details
Overview
LT3971IMSE#PBF from Analog Devices (formerly Linear Technology) is a 38V, 1.2A monolithic synchronous step-down DC/DC regulator in a 10-lead MSOP package with exposed pad. It delivers ultralow 2.8µA quiescent current in regulation, supports adjustable switching frequency from 200kHz to 2MHz, and integrates a 0.33Ω bipolar NPN switch, boost Schottky diode, and internal compensation. 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 LT3971IMSE#PBF datasheet, LT3971IMSE#PBF pinout, LT3971IMSE#PBF application, or LT3971IMSE#PBF equivalent, key selection factors include its 4.3V–38V input range, 1.19V–30V programmable output, 1.2A continuous output current, Burst Mode® operation with <15mVP-P ripple, and accurate 1V enable threshold with 700nA shutdown current.
Technical Context
The LT3971IMSE#PBF employs a constant-frequency current-mode control architecture with internal slope compensation for fast transient response and stable loop behavior across line/load/temperature. Its oscillator is resistor-programmable via the RT pin and synchronizable externally through the SYNC pin (250kHz–2MHz range).
It features low-ripple Burst Mode® operation that maintains high efficiency at light loads by delivering discrete current pulses followed by deep sleep intervals-reducing no-load supply current to 2.8µA while holding output ripple below 15mVP-P. The integrated boost circuit drives the internal switch using a charge-pump-generated voltage on the BOOST pin, enabling full saturation of the bipolar NPN transistor even at high input voltages.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.3V to 38V - supports direct connection to 12V/24V/36V automotive and industrial rails without pre-regulation. |
| Output Current | 1.2A continuous - 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% - sets precise output voltage with external resistor divider; enables 1.19V–30V programmability. |
| Power Good Flag | Open-drain PG output asserting when VFB reaches 91% of regulation - provides reliable system power sequencing and fault detection. |
| Shutdown Current | 700nA - ensures near-zero leakage during system sleep modes, critical for energy harvesting and backup power. |
Pinout & Package
LT3971IMSE#PBF is housed in a thermally enhanced 10-lead plastic MSOP package (3mm × 3mm footprint) with exposed pad (Pin 11) soldered to PCB ground for low θJA = 45°C/W and θJC = 10°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (Pin 1) | Boost Diode Anode Connection | Connects to cathode of external Schottky diode; forms bootstrap path for internal switch drive. |
| BOOST (Pin 2) | Charge Pump Output | Provides >VIN voltage to fully saturate internal bipolar NPN switch; requires external capacitor to SW. |
| SW (Pin 3) | Switch Node | Drives external inductor and catch diode; carries high di/dt switching current; must be minimized in layout area. |
| VIN (Pin 4) | Main Input Supply | Supplies internal bias and switch current; requires local ceramic bypass capacitor (≥1µF) close to pin. |
| EN (Pin 5) | Enable Control | Hysteretic 1.005V rising / 0.975V falling threshold; pulls device into 700nA shutdown when low. |
| FB (Pin 6) | Feedback Input | Regulated to 1.19V; connects to resistor divider tap; phase-lead capacitor (10pF) recommended from FB to VOUT. |
| SS (Pin 7) | Soft-Start Control | Capacitor to GND ramps peak current limit at startup; prevents inrush; floats to disable soft-start. |
| RT (Pin 8) | Frequency Set | Resistor to GND programs switching frequency from 200kHz to 2MHz per datasheet table. |
| PG (Pin 9) | Power Good Flag | Open-drain output active-low until VFB ≥ 91% of target; requires external pull-up for logic-level signaling. |
| SYNC (Pin 10) | External Clock Input | Ground for Burst Mode; tie to external clock (250kHz–2MHz) for synchronization and pulse-skipping mode. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow Quiescent Current | 2.8µA regulating 12VIN to 3.3VOUT - extends battery runtime in always-on sensor nodes and telematics modules. |
| Low-Ripple Burst Mode® | Output ripple <15mVP-P at light loads - eliminates need for post-regulation LDOs in noise-sensitive analog signal chains. |
| Internal Compensation | No external compensation components required - reduces BOM count and design iteration time for standard buck topologies. |
| Integrated Boost Diode | On-chip Schottky diode eliminates external boost diode - simplifies layout and improves reliability in space-constrained designs. |
| Accurate Power Good Flag | ±100mV PG threshold offset from VFB - enables deterministic power sequencing in multi-rail embedded systems. |
Applications
| Automotive Body Control Module | Industrial Sensor Transmitter |
|---|---|
Use Scenario: Powers MCU, CAN transceiver, and analog front-end from 12V battery rail under cold-crank (6V) and load-dump (36V) conditions. IC Role / Device Role / Timing Role: Primary 3.3V/5V point-of-load regulator with wide-input tolerance and robust thermal performance. Use Value: Maintains regulation down to 4.3V input and survives 38V transients; 2.8µA IQ enables ECU wake-on-CAN without battery drain. |
Use Scenario: Supplies 3.3V to 4–20mA loop transmitter ICs and precision ADCs in hazardous-area field instruments. IC Role / Device Role / Timing Role: Isolated auxiliary supply regulator with low EMI and minimal self-heating in sealed enclosures. Use Value: Burst Mode® operation keeps temperature rise <5°C at 100µA load; 15mVP-P ripple avoids ADC quantization errors. |
| Portable Medical Monitor | Smart Meter Battery Backup |
Use Scenario: Powers display controller and wireless SoC from coin-cell or Li-ion battery in handheld diagnostic devices. IC Role / Device Role / Timing Role: High-efficiency buck converter with soft-start and PG flag for safe boot sequencing. Use Value: 700nA shutdown current preserves battery capacity during storage; SS pin enables controlled inrush into large display capacitance. |
Use Scenario: Provides regulated 3.3V to RTC and memory during main AC power failure in utility meters. IC Role / Device Role / Timing Role: Ultra-low-IQ backup regulator sustaining SRAM and real-time clock for >10 years on supercapacitor. Use Value: 2.8µA operating IQ and 700nA shutdown IQ maximize hold-up time; internal 10MΩ feedback divider minimizes external component count. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EMSE#PBF | 42V input, 3.5A output, 2.5µA IQ, Silent Switcher® architecture | Lower EMI, higher current, but larger package (16-lead MSE); requires different layout for EMI suppression | Select when radiated emissions compliance (CISPR 25 Class 5) is mandatory and 3.5A output is needed. |
| TPS62130ARGTR | 6V max input, 3A output, 17µA IQ, 2.5MHz fixed frequency | Not suitable for automotive or industrial 12V+ inputs; lacks Burst Mode® and wide-VIN capability | Consider only for low-voltage consumer applications where cost and size outweigh wide-input requirements. |
Compared with LT3971IMSE#PBF, LT8610EMSE#PBF offers superior EMI performance and higher current but increases board area and complexity; TPS62130ARGTR provides lower cost and higher frequency but cannot replace LT3971IMSE#PBF in 12V–36V systems due to its 6V input limit.
Availability
LT3971IMSE#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial sensor power, and portable medical monitoring requiring stable component supply and long-term lifecycle support.
Supply support for LT3971IMSE#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 its legacy of high-performance power management ICs with rigorous automotive-grade qualification and long-term product availability.
The LT3971 family was designed for wide-input, ultralow-quiescent-current DC/DC conversion in harsh environments-targeting automotive, industrial, and battery-powered instrumentation where reliability and efficiency coexist.
FAQ
What is the maximum input voltage rating for LT3971IMSE#PBF?
The absolute maximum input voltage for LT3971IMSE#PBF is 38V on the VIN pin. Operation above 38V risks permanent damage. For reliable regulation, the maximum operating input voltage depends on switching frequency and output voltage-calculated as VIN(OP-MAX) = (VOUT + VD)/(fSW × tON(MIN)) – VD + VSW. At 2MHz and 3.3V output, practical VIN is limited to ~24V to maintain duty cycle margin and low ripple.
Does LT3971IMSE#PBF require an external catch diode?
No, LT3971IMSE#PBF does not require an external catch diode because it integrates a Schottky diode connected between the BD and SW pins. However, an external Schottky diode must still be placed between BD and VOUT to complete the bootstrap circuit for the internal switch driver. This external diode must have ≤1µA reverse leakage at room temperature to preserve ultralow quiescent current performance.
Can LT3971IMSE#PBF operate in Burst Mode® with SYNC pin floating?
No-Burst Mode® operation requires the SYNC pin to be grounded. If SYNC is left floating or tied high, the device defaults to pulse-skipping mode at light loads, increasing quiescent current to ~1.5mA and raising output ripple. Grounding SYNC enables true low-ripple Burst Mode® with 2.8µA no-load IQ and <15mVP-P ripple in typical applications.
What is the purpose of the SS pin on LT3971IMSE#PBF?
The SS (soft-start) pin on LT3971IMSE#PBF controls inrush current during startup by ramping the internal current limit. A capacitor from SS to GND creates a linear voltage ramp that gradually increases peak switch current, preventing output overshoot and limiting input surge. The SS pin is released when EN goes high; it is actively discharged only during shutdown. Floating SS disables soft-start entirely.
Is LT3971IMSE#PBF pin-compatible with LT3971EMSE#PBF?
Yes, LT3971IMSE#PBF and LT3971EMSE#PBF share identical 10-lead MSOP pinout, electrical specifications, and thermal characteristics. The only difference is temperature grade: LT3971IMSE#PBF is rated for –40°C to 125°C junction temperature and is guaranteed over the full range, while LT3971EMSE#PBF is specified for 0°C to 125°C (with performance assured by design over –40°C to 125°C). Both use the same LTFJG marking and package dimensions.
LT3971IMSE#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
LT3971IMSE#PBF FAQ
1.How can I place an order for LT3971IMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3971IMSE#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 LT3971IMSE#PBF reliable?
The price and inventory of LT3971IMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3971IMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3971IMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3971IMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3971IMSE#PBF?
LT3971IMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3971IMSE#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 LT3971IMSE#PBF?
For technical support, including LT3971IMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3971IMSE#PBF requirements.
6.How does Aetrix verify that LT3971IMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3971IMSE#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 LT3971IMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3971IMSE#PBF?
All LT3971IMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3971IMSE#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 LT3971IMSE#PBF part is unused and in its original packaging.
Return procedure for LT3971IMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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