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Analog Devices Inc. LT3971IDD-5#TRPBF
- Part No.:
- LT3971IDD-5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3971IDD-5#TRPBF.pdf
- Description:
- IC REG BUCK 5V 1.2A 10DFN
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT3971IDD-5#TRPBF from Analog Devices (formerly Linear Technology) is a fixed 5V, 1.2A monolithic step-down switching regulator in a thermally enhanced 10-lead (3mm × 3mm) DFN package. It operates from 4.3V to 38V input, delivers ultralow 2.8µA quiescent current in Burst Mode, maintains <15mVP-P output ripple, and integrates a 0.33Ω switch, boost Schottky diode, and power good flag - ideal for automotive battery regulation and portable power supplies.
For engineers reviewing the LT3971IDD-5#TRPBF datasheet, LT3971IDD-5#TRPBF pinout, LT3971IDD-5#TRPBF application, or LT3971IDD-5#TRPBF equivalent, key selection criteria include its fixed 5V output, 2.8µA no-load IQ, 1.2A output capability, 200kHz–2MHz adjustable frequency, and thermal performance in the exposed-pad DFN package.
Technical Context
The LT3971IDD-5#TRPBF implements constant-frequency current-mode control with internal compensation, enabling fast transient response and stable loop behavior across wide input and load ranges. Its architecture includes an integrated bipolar NPN power switch driven by a BOOST pin voltage higher than VIN, ensuring full saturation and low conduction loss.
Burst Mode operation reduces input supply current to 1.7µA during sleep cycles while maintaining regulation; combined with a 1V enable threshold and 700nA shutdown current, it supports always-on systems requiring extended battery life. The device features frequency foldback during startup/overload and a 91% VOUT power-good comparator with open-drain PG output.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.0V ±1.5%, internally regulated via 10MΩ feedback divider - eliminates external resistor network for stable 5V rail generation. |
| Input Voltage Range | 4.3V to 38V - supports direct connection to 12V/24V/36V automotive and industrial bus systems without pre-regulation. |
| Max Output Current | 1.2A continuous - sufficient for powering microcontrollers, sensors, and communication ICs in compact embedded designs. |
| Quiescent Current | 2.8µA at no load (12VIN → 5VOUT) - enables multi-year battery operation in IoT and telematics applications. |
| Switching Frequency | 200kHz to 2MHz (RT-programmable) - allows optimization of inductor size (e.g., 4.7µH at 800kHz) vs. efficiency tradeoffs. |
| Output Ripple | <15mVP-P in typical application - meets noise-sensitive analog and RF subsystem requirements without additional LDO post-regulation. |
| Thermal Resistance | θJA = 45°C/W, θJC = 10°C/W - enabled by exposed GND pad soldered to PCB - supports 1.2A operation at TJ ≤ 125°C in ambient up to 85°C. |
Pinout & Package
LT3971IDD-5#TRPBF uses a 10-lead (3mm × 3mm) plastic DFN package with exposed thermal pad (Pin 11 = GND), optimized for low thermal resistance and space-constrained layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BD (Pin 1) | Boost Diode Anode Connection | Connects to cathode of external Schottky diode; forms bootstrap path for high-side drive of internal NPN switch. |
| BOOST (Pin 2) | Bootstrap Drive Voltage Source | Provides >VIN voltage to fully saturate internal bipolar switch; requires external capacitor between BOOST and SW. |
| SW (Pin 3) | Internal Switch Drain Node | High-current switching node connected to inductor, catch diode, and BOOST capacitor - critical for EMI layout. |
| VIN (Pin 4) | Main Power Input | Supplies internal circuitry and switch; must be locally bypassed with low-ESR ceramic capacitor near pin. |
| EN (Pin 5) | Enable Control Input | Hysteretic 1.005V rising / 0.975V falling threshold; pulls to GND for shutdown (700nA IQ). |
| VOUT (Pin 6) | Fixed 5V Output Sense | Internally regulated to 5.0V; connects to output capacitor and load - replaces FB pin used in adjustable variants. |
| SS (Pin 7) | Soft-Start Control | Capacitor-to-GND sets controlled inrush current ramp; discharged only when EN is low. |
| RT (Pin 8) | Frequency Set Resistor | 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 VOUT reaches 91% of 5V (i.e., 4.55V); requires external pull-up. |
| SYNC (Pin 10) | External Clock Input | Ground for Burst Mode; tie to external clock (250kHz–2MHz) for synchronization - increases light-load IQ to 1.5mA. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow Quiescent Current | 2.8µA at no load enables >10-year battery life in always-on monitoring nodes powered from coin cells or LiSOCl₂. |
| Low-Ripple Burst Mode | Maintains <15mVP-P output ripple while delivering single current pulses - avoids audible noise and preserves signal integrity in analog front-ends. |
| Integrated Power Components | On-die 0.33Ω switch, boost Schottky diode, oscillator, and error amplifier reduce BOM count by ≥4 components vs. controller-based solutions. |
| Robust Thermal Design | Exposed GND pad (Pin 11) provides 10°C/W junction-to-case resistance - sustains 1.2A output at 85°C ambient without derating. |
| Accurate Power Good Flag | PG asserts when VOUT reaches 4.55V (91% of 5V) with 9mV hysteresis - enables reliable system sequencing and fault detection. |
Applications
| Automotive Body Control Module | Industrial Sensor Node |
|---|---|
Use Scenario: Powering CAN transceiver, microcontroller, and temperature/humidity sensor from 12V vehicle battery with cold-crank tolerance down to 4.3V. IC Role / Device Role / Timing Role: Primary 5V DC-DC converter providing regulated rail with ultralow IQ to extend battery life during ignition-off periods. Use Value: 2.8µA quiescent current prevents parasitic drain; 38V absolute max rating withstands load-dump transients up to 36V. | Use Scenario: Remote wireless sensor unit operating on two AA alkaline cells (1.8–3.2V) with boost converter feeding LT3971IDD-5#TRPBF for stable 5V supply. IC Role / Device Role / Timing Role: Secondary step-down regulator accepting boosted 12V input to generate precise 5V for ADC reference and RF transceiver. Use Value: Wide 4.3–38V input range accommodates variable upstream boost output; 1.2A capacity supports burst transmission peaks. |
| Portable Medical Monitor | Smart Building Controller |
Use Scenario: Battery-powered ECG monitor requiring clean 5V rail for analog front-end and Bluetooth LE module with multi-week runtime. IC Role / Device Role / Timing Role: Main power regulator operating in Burst Mode during standby, transitioning to PWM under active measurement load. Use Value: <15mVP-P ripple eliminates need for post-regulation LDO; 2.8µA IQ extends battery life beyond 30 days on 2000mAh Li-ion. | Use Scenario: DIN-rail mounted HVAC controller drawing power from 24VAC rectified supply with brownout resilience. IC Role / Device Role / Timing Role: Primary 5V supply for ARM Cortex-M7 MCU, isolated RS-485 transceivers, and EEPROM memory. Use Value: 38V max input handles rectified 24VAC peaks (~34V); PG flag synchronizes firmware boot with stable 5V rail. |
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 |
|---|---|---|---|
| LMR36520RNXR | 65V max input, 2A output, 26µA IQ, 2.1MHz fixed frequency - no Burst Mode, higher IQ, wider VIN range. | Preferred for 48V industrial systems where 38V limit of LT3971IDD-5#TRPBF is insufficient. | Select when input voltage exceeds 38V or >2A output is required; accept higher light-load IQ and no low-ripple Burst Mode. |
| TPS54202DRCT | 6V max input, 2A output, 2µA IQ (Eco-mode), 2.5MHz sync-capable - lower VIN range, smaller package (SOT-23-6), no integrated boost diode. | Suitable for 5V-input systems (e.g., USB PD secondary side) where size and ultra-low IQ dominate over input range. | Choose for space-constrained 5V-input designs needing minimal footprint; verify external boost diode and gate driver compatibility. |
Compared with LMR36520RNXR and TPS54202DRCT, the LT3971IDD-5#TRPBF uniquely balances 38V input tolerance, 2.8µA IQ, integrated boost diode, and <15mV ripple - making it optimal for automotive and wide-input industrial 5V rails where both robustness and battery longevity matter.
Availability
LT3971IDD-5#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial sensor nodes, portable medical monitors, and smart building controllers requiring stable component supply with guaranteed long-term availability.
Supply support for LT3971IDD-5#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 its high-performance power management portfolio with rigorous automotive and industrial qualification standards.
The LT3971 family was designed specifically for ultralow-quiescent-current step-down conversion in battery-backed and always-on systems - emphasizing thermal efficiency, input voltage resilience, and minimal external component count.
FAQ
What is the output voltage tolerance of the LT3971IDD-5#TRPBF over temperature and line?
The LT3971IDD-5#TRPBF delivers a fixed 5.0V output with ±1.5% total tolerance over –40°C to 125°C junction temperature and 4.3V to 38V input range. Electrical characteristics show 4.93V to 5.07V (min/max) at TA = 25°C and 4.89V to 5.11V over full temperature range - verified by internal 10MΩ resistor divider and 1.19V reference accuracy.
Does the LT3971IDD-5#TRPBF require an external feedback resistor network?
No, the LT3971IDD-5#TRPBF does not require external feedback resistors. It integrates a precision 10MΩ internal resistor divider and phase-lead capacitor to regulate the VOUT pin directly to 5.0V - simplifying design, improving accuracy, and eliminating resistor-induced load current that degrades ultralow-IQ performance.
How does the LT3971IDD-5#TRPBF achieve 2.8µA quiescent current?
The LT3971IDD-5#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 consuming only 1.7µA between bursts. Combined with optimized biasing and internal power gating, this yields 2.8µA total input current at no load (12VIN → 5VOUT), as measured per datasheet Figure G06.
Can the LT3971IDD-5#TRPBF be synchronized to an external clock?
Yes, the LT3971IDD-5#TRPBF can be synchronized using the SYNC pin (Pin 10). When driven with a 250kHz–2MHz external clock, it locks switching frequency and phase. However, synchronization disables Burst Mode and forces pulse-skipping at light loads, increasing quiescent current to 1.5mA - so ground SYNC only if ultralow IQ is critical.
What thermal considerations apply to the LT3971IDD-5#TRPBF in a 1.2A application?
For 1.2A continuous operation, the LT3971IDD-5#TRPBF requires the exposed GND pad (Pin 11) to be soldered to a minimum 100mm² copper area with ≥4 thermal vias to internal ground planes. With θJA = 45°C/W, 1.2A at 12VIN/5VOUT yields ~0.6W dissipation - limiting junction temperature to ≤105°C at 85°C ambient, well within the –40°C to 125°C rated range.
LT3971IDD-5#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN 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):
- 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-DFN (3x3)
LT3971IDD-5#TRPBF FAQ
1.How can I place an order for LT3971IDD-5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3971IDD-5#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 LT3971IDD-5#TRPBF reliable?
The price and inventory of LT3971IDD-5#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3971IDD-5#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3971IDD-5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3971IDD-5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3971IDD-5#TRPBF?
LT3971IDD-5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3971IDD-5#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 LT3971IDD-5#TRPBF?
For technical support, including LT3971IDD-5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3971IDD-5#TRPBF requirements.
6.How does Aetrix verify that LT3971IDD-5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3971IDD-5#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 LT3971IDD-5#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3971IDD-5#TRPBF?
All LT3971IDD-5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3971IDD-5#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 LT3971IDD-5#TRPBF part is unused and in its original packaging.
Return procedure for LT3971IDD-5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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