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Analog Devices Inc. LT3971IMSE-5#PBF
- Part No.:
- LT3971IMSE-5#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3971IMSE-5#PBF.pdf
- Description:
- IC REG BUCK 5V 1.2A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:178
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Product details
Overview
LT3971IMSE-5#PBF from Analog Devices (formerly Linear Technology) is a fixed 5V, 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 maintains <15mVP-P output ripple via low-ripple Burst Mode® operation. Used in automotive battery regulation and portable power supplies where standby efficiency and wide VIN range are critical.
For engineers reviewing the LT3971IMSE-5#PBF datasheet, LT3971IMSE-5#PBF pinout, LT3971IMSE-5#PBF application, or LT3971IMSE-5#PBF equivalent, key selection criteria include its fixed 5V output, 2.8µA no-load IQ, 1.2A output capability, 200kHz–2MHz adjustable frequency, and integrated boost Schottky diode-enabling compact, high-efficiency step-down conversion in space-constrained industrial and automotive systems.
Technical Context
The LT3971IMSE-5#PBF 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 5.00V ±1.4% over temperature and line, using an internal 10MΩ resistor divider and built-in phase-lead capacitor.
Burst Mode® operation reduces input supply current to 1.7µA during sleep intervals while delivering discrete current pulses to maintain regulation; SYNC pin grounding enables this mode, whereas external synchronization increases light-load IQ to 1.5mA. Power Good (PG) signals when VOUT reaches 91% of nominal, with 9% hysteresis for noise immunity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.00V ±1.4% (–40°C to 125°C), set by internal 10MΩ divider - eliminates external resistors and improves accuracy. |
| Input Voltage Range | 4.3V to 38V - supports 12V/24V/36V automotive and industrial rails without pre-regulation. |
| No-Load Quiescent Current | 2.8µA at 12VIN → 5VOUT - enables multi-year battery life in always-on IoT sensors and telematics modules. |
| Max Output Current | 1.2A continuous - sufficient for powering microcontrollers, CAN transceivers, and small displays from a single stage. |
| Switching Frequency | Adjustable 200kHz–2MHz via RT resistor - allows tradeoff between inductor size (e.g., 4.7µH @ 800kHz) and efficiency. |
| Output Ripple (Burst Mode) | <15mVP-P typical - achieved without external LC filters, reducing BOM count and board area. |
| Power Good Threshold | VOUT ≥ 91% of 5V (i.e., ≥4.55V) - provides reliable system reset signaling with 5.5% hysteresis. |
Pinout & Package
LT3971IMSE-5#PBF uses a thermally enhanced 10-lead MSOP package (3mm × 3mm footprint, 0.85mm height) with exposed pad (Pin 11) soldered to PCB for low θJA = 45°C/W. Pin numbering follows standard top-view MSOP orientation.
| 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) | Bootstrap Drive Voltage | Provides >VIN voltage to fully saturate internal NPN switch; requires external 10nF ceramic capacitor to SW. |
| SW (Pin 3) | Switch Node | Drives external inductor and catch diode; carries high di/dt - requires tight layout and ground plane. |
| VIN (Pin 4) | Main Input Supply | Supplies IC bias and switch current; must be locally bypassed with ≥10µF ceramic + 0.1µF near pin. |
| EN (Pin 5) | Enable Control | Hysteretic threshold (0.95V–1.07V); pulls VIN current to 700nA in shutdown - enables system-level power sequencing. |
| VOUT (Pin 6) | Regulated Output | Fixed 5V output node; connects to load and feedback network; internal 10MΩ divider referenced to this pin. |
| SS (Pin 7) | Soft-Start Control | Capacitor to GND sets inrush current ramp rate; prevents input voltage sag during startup. |
| RT (Pin 8) | Frequency Set | Resistor to GND programs switching frequency (e.g., 49.9kΩ = 800kHz); enables EMI optimization. |
| PG (Pin 9) | Power Good Flag | Open-drain output; pulled high externally; asserts when VOUT ≥ 4.55V - used for µC reset or enable chaining. |
| SYNC (Pin 10) | External Clock Input | Ground for Burst Mode; tie to external clock (250kHz–2MHz) for synchronization - disables ultralow IQ mode. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow Quiescent Current | 2.8µA IQ at no load enables >10-year battery life in always-on monitoring devices powered from coin cells or supercaps. |
| Integrated Boost Schottky Diode | On-die BD pin connection eliminates external boost diode - reduces component count and improves reliability in harsh environments. |
| Low-Ripple Burst Mode® | Maintains <15mVP-P output ripple at light loads without external filtering - simplifies EMI compliance and saves board space. |
| Accurate Fixed 5V Output | ±1.4% tolerance over –40°C to 125°C ensures stable logic supply for MCUs, sensors, and interface ICs without trimming. |
| Thermally Enhanced MSOP | Exposed pad (Pin 11) soldered to PCB achieves θJA = 45°C/W - supports 1.2A continuous output without heatsink in 70°C ambient. |
Applications
| Automotive Body Control Module | Industrial Sensor Node |
|---|---|
Use Scenario: Powers MCU, CAN transceiver, and analog front-end in door module operating from 9V–16V battery with cold-crank down to 4.5V. IC Role / Device Role / Timing Role: Primary 5V rail generator with wide-input tolerance and ultralow IQ to extend battery backup during ignition-off periods. Use Value: Delivers regulated 5V at 1.2A with 2.8µA no-load draw - enabling >3-month battery hold-up without recharge circuitry. | Use Scenario: Supplies 5V to low-power wireless sensor (LoRaWAN/NB-IoT) deployed in remote field locations with primary AA/AAA battery source. IC Role / Device Role / Timing Role: Standby-optimized DC-DC converter maintaining system readiness while minimizing self-discharge. Use Value: Achieves 2.8µA IQ and <15mV ripple - extending usable battery life from 2 to 7 years versus conventional buck regulators. |
| Portable Medical Monitor | Railway Onboard Telematics |
Use Scenario: Powers display controller and data acquisition ASIC in handheld ECG monitor requiring clean, quiet 5V rail from single-cell Li-ion (3.0V–4.2V) with boost-capable input. IC Role / Device Role / Timing Role: Input-flexible buck regulator accepting boosted input up to 38V - accommodates emergency 24V auxiliary supply. Use Value: Maintains regulation across full battery discharge curve and external supply transitions - eliminating need for dual-path power architecture. | Use Scenario: Provides 5V for GPS/GSM module and microcontroller in train-mounted condition monitoring unit exposed to 72V transients and –40°C to +85°C ambient. IC Role / Device Role / Timing Role: Robust primary converter with 38V absolute max rating and AEC-Q200-compatible thermal design. Use Value: Survives ISO 7637-2 pulse 5a (75V/100ms) with proper input clamping - reducing need for upstream TVS stages. |
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 |
|---|---|---|---|
| LTC3631EMSE-5#PBF | Same 5V fixed output, but 100mA max IOUT; uses CMOS switch instead of bipolar; 3.5µA IQ. | Not suitable for 1.2A loads; intended for low-power logic rails only. | Select only if output current ≤100mA and bipolar switch stress is undesirable. |
| TPS54202DRCT | Adjustable output (0.6V–6V); 2A max IOUT; 26µA IQ; requires external feedback resistors. | Higher IQ and external components increase solution size and reduce standby efficiency. | Choose when output voltage flexibility or higher current is required, accepting 9× higher no-load IQ. |
Compared with LTC3631EMSE-5#PBF and TPS54202DRCT, the LT3971IMSE-5#PBF uniquely combines 1.2A capability, 5V fixed output, and sub-3µA quiescent current in a thermally optimized MSOP - making it optimal for space- and battery-limited 5V systems where efficiency at microamp loads is non-negotiable.
Availability
LT3971IMSE-5#PBF is available at Aetrix Electronics and suitable for automotive body control modules, industrial sensor nodes, and portable medical monitors requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LT3971IMSE-5#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3971 product line was designed specifically for ultralow-quiescent-current DC-DC conversion in battery-backed and energy-harvesting systems - emphasizing wide input range, integrated power stages, and robust thermal performance in miniature packages.
FAQ
What is the output voltage tolerance of the LT3971IMSE-5#PBF over temperature?
The LT3971IMSE-5#PBF guarantees a 5V output with ±1.4% tolerance across the full –40°C to +125°C junction temperature range, as confirmed by electrical characterization in the official datasheet. This accuracy is achieved using an internal 10MΩ feedback divider and trimmed bandgap reference, eliminating drift-related calibration needs in the LT3971IMSE-5#PBF design.
Does the LT3971IMSE-5#PBF require external feedback resistors?
No, the LT3971IMSE-5#PBF integrates a precision 10MΩ resistor divider and internal phase-lead capacitor to set the fixed 5V output - eliminating external resistors and associated tolerance errors. This simplifies layout, improves long-term stability, and reduces BOM cost compared to adjustable regulators like the base LT3971, which require external FB resistors.
How does the LT3971IMSE-5#PBF achieve 2.8µA quiescent current?
The LT3971IMSE-5#PBF achieves 2.8µA quiescent current through low-ripple Burst Mode® operation: it delivers discrete current pulses to the output capacitor during light loads, then enters deep sleep consuming only 1.7µA between bursts. The LT3971IMSE-5#PBF's internal architecture minimizes bias currents in error amp, oscillator, and gate drivers - validated at 12VIN → 5VOUT with no load.
Can the LT3971IMSE-5#PBF operate from a 36V input?
Yes, the LT3971IMSE-5#PBF supports input voltages up to 38V continuously, making it fully compatible with 36V industrial and railway systems. At 36VIN, it maintains 5VOUT regulation at up to 1.2A with typical efficiency >85% (per Figure G02), provided thermal design accommodates power dissipation - verified in the LT3971IMSE-5#PBF absolute maximum ratings and thermal performance data.
What is the function of the SS pin on the LT3971IMSE-5#PBF?
On the LT3971IMSE-5#PBF, the SS (soft-start) pin controls inrush current by ramping the internal peak current limit during startup. A capacitor from SS to GND sets the ramp time - preventing input voltage sag and output overshoot. When EN is low, the SS pin is actively discharged; floating SS disables soft-start. For inputs >25V, a 100kΩ series resistor is recommended to limit SS pin current in the LT3971IMSE-5#PBF.
LT3971IMSE-5#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:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.3V
- Voltage - Input (Max):
- 38V
- Voltage - Output (Min/Fixed):
- 5V
- 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-5#PBF FAQ
1.How can I place an order for LT3971IMSE-5#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3971IMSE-5#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-5#PBF reliable?
The price and inventory of LT3971IMSE-5#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-5#PBF is usually 5 days.
3.What payment methods are accepted for LT3971IMSE-5#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3971IMSE-5#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3971IMSE-5#PBF?
LT3971IMSE-5#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3971IMSE-5#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-5#PBF?
For technical support, including LT3971IMSE-5#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3971IMSE-5#PBF requirements.
6.How does Aetrix verify that LT3971IMSE-5#PBF is sourced from the original manufacturer or authorized distributors?
All LT3971IMSE-5#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-5#PBF meets industry standards.
7.What is the process for return or replacement of LT3971IMSE-5#PBF?
All LT3971IMSE-5#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3971IMSE-5#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-5#PBF part is unused and in its original packaging.
Return procedure for LT3971IMSE-5#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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