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Analog Devices Inc. LT3431EFE#PBF
- Part No.:
- LT3431EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3431EFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 3A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:281
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Product details
Overview
LT3431EFE#PBF from Analog Devices (formerly Linear Technology) is a high-voltage, current-mode synchronous step-down DC/DC regulator IC with integrated 3A NPN power switch, 500kHz fixed switching frequency, 1.22V feedback reference, and operation up to 60V input. It delivers up to 2A at 5V output in thermally enhanced 16-pin TSSOP package and is used in industrial power supplies requiring wide VIN range and robust transient response.
For engineers reviewing the LT3431EFE#PBF datasheet, LT3431EFE#PBF pinout, LT3431EFE#PBF application, or LT3431EFE#PBF equivalent, key selection considerations include its 3A peak switch current capability across full duty cycle, BOOST pin–enabled saturation drive for 0.1Ω effective RDS(on), –40°C to 125°C junction temperature rating, and cycle-by-cycle current limiting with foldback protection during short-circuit conditions.
Technical Context
The LT3431EFE#PBF implements a constant-frequency current-mode control architecture with dual feedback loops: an error amplifier sets the peak switch current threshold via the VC pin, while a current-sense comparator monitors switch emitter voltage on each cycle. Its patented slope compensation cancellation maintains 3A peak switch current limit from 0% to 92% duty cycle without degradation.
Internal bias regulation draws from VIN or externally supplied BIAS pin (≥3V), improving efficiency at high input-to-output ratios. The BOOST pin enables external charge-pump drive (via diode + capacitor) to saturate the internal NPN switch, reducing conduction loss to ~0.1Ω. Shutdown and UVLO are implemented via dual-threshold SHDN pin (0.4V shutdown, 2.38V lockout).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5.5V to 60V - supports 12V/24V/48V industrial rails and transient-tolerant automotive inputs |
| Switch Current Limit | 3.0A (min) at TJ = 25°C - sustained over full duty cycle range, enabling stable 2A continuous output |
| Feedback Reference | 1.219V (typ) - precise setpoint for output voltage divider; ±1.2% tolerance over temperature |
| Switching Frequency | 500kHz (typ) - fixed frequency enables predictable EMI filtering; synchronizable from 580kHz to 700kHz |
| Package Thermal Resistance | θJA = 45°C/W - exposed pad soldered to ground plane required for thermal performance at full load |
| Shutdown Current | 30µA (typ) - ultra-low quiescent draw enables battery-backed or always-on systems |
| Operating Junction Temp | –40°C to 125°C - qualified for extended industrial and under-hood automotive environments |
Pinout & Package
LT3431EFE#PBF is housed in a 16-lead plastic TSSOP package with exposed GND pad (FE variant). The exposed pad must be soldered to a PCB ground plane to achieve specified thermal performance (θJC = 10°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (1, 8, 9, 16) | Power and signal reference ground | Multiple low-inductance ground paths; exposed pad fused to all GND pins - critical for noise immunity and thermal dissipation |
| SW (2, 5) | Switch emitter node | Drives inductor; swings negative during off-time - requires external catch diode clamping to –0.8V max |
| VIN (3, 4) | Power switch collector & primary supply | Supplies internal circuitry when BIAS pin unused; high dI/dt node - demands short, low-inductance path to input capacitor |
| BOOST (6) | Switch driver boost supply | Accepts voltage ≥VIN+1.8V; provides saturated drive to NPN base - enables 0.1Ω effective on-resistance |
| BIAS (10) | Efficiency-optimized bias supply | Connect to VOUT ≥3V to shift internal bias current from VIN to output - improves efficiency at high VIN/VOUT ratios |
| VC (11) | Error amplifier output / current limit control | Directly sets peak switch current; ranges from ~0.9V (light load) to 2.1V (full load); clampable for override |
| FB (12) | Output voltage sensing input | 1.22V reference target; also enables foldback: frequency reduction below 0.8V, current limit reduction below 0.6V |
| SYNC (14) | External oscillator synchronization | Logic-level compatible; accepts 580–700kHz square wave with 10–90% duty cycle - eliminates beat frequencies |
| SHDN (15) | Enable/disable control with UVLO | Dual-threshold: 2.38V disables switching (UVLO), 0.4V forces micropower shutdown (30µA IQ) |
Key Features
| Feature | Design Value |
|---|---|
| Patented duty-cycle–invariant current limit | Maintains 3A peak switch current from 0% to 92% duty cycle - eliminates need for derating at high VIN/VOUT ratios |
| BOOST-driven saturated NPN switch | 0.1Ω typical on-resistance achieved via external BOOST capacitor/diode - reduces conduction loss vs. standard bipolar design |
| Integrated feedback reference and error amplifier | 1.219V ±1.2% reference with 2200 µ℧ transconductance - enables stable loop compensation with ceramic output capacitors |
| Foldback protection on FB pin | Automatically reduces switching frequency (5:1) below 0.8V FB and limits peak current below 0.6V - protects IC and external components during short-circuit |
| Thermally enhanced FE package | 16-pin TSSOP with exposed GND pad - achieves θJA = 45°C/W when pad is soldered to ≥1 in² ground plane |
Applications
| Industrial Power Supply | Automotive Body Control Module |
|---|---|
|
Use Scenario: 24V vehicle battery powers 5V microcontroller, CAN transceiver, and sensors in door module. IC Role / Device Role / Timing Role: Primary buck regulator converting 9–36V battery range to stable 5V rail with transient immunity up to 60V. Use Value: Maintains regulation during cold-crank (6.5V) and load-dump (60V) events; 125°C rating ensures reliability in sealed enclosures. |
Use Scenario: DIN-rail mounted programmable logic controller (PLC) requires isolated 5V/2A for I/O modules and fieldbus interface. IC Role / Device Role / Timing Role: Non-isolated front-end regulator accepting 12–48V DC input and delivering tightly regulated 5V output. Use Value: 60V absolute max input withstands surge transients per IEC 61000-4-5; 3A switch handles inrush of multiple downstream LDOs. |
| Portable Medical Instrument | Distributed Telecom Power |
|
Use Scenario: Battery-powered ultrasound probe uses Li-ion (3.0–4.2V) and 12V boost stage to feed LT3431EFE#PBF for 5V imaging subsystem. IC Role / Device Role / Timing Role: Secondary buck converter stepping down 12V intermediate rail to low-noise 5V for analog front-end and FPGA core. Use Value: 500kHz fixed frequency simplifies EMI filter design; BIAS pin connection to 5V output improves light-load efficiency by >8% vs. VIN biasing. |
Use Scenario: 48V telecom shelf supplies 5V/2A to remote radio head (RRH) control board with strict thermal constraints. IC Role / Device Role / Timing Role: High-efficiency point-of-load regulator placed near FPGA and ADC, minimizing IR drop and noise coupling. Use Value: Exposed-pad TSSOP enables direct mounting to copper pour; SYNC pin allows alignment with system clock to suppress beat tones. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8609S#PBF | 42V max input, 3A peak, 2MHz sync capability, integrated MOSFETs, 2.5µA quiescent current | Better suited for space-constrained designs needing higher fSW; lacks BOOST pin and BIAS pin functionality | Select LT8609S#PBF when board area is critical and input ≤42V; retain LT3431EFE#PBF for 60V input or BIAS-driven efficiency optimization. |
| MPQ4433AGL-A-Z | 60V max input, 3.5A peak, 500kHz, integrated MOSFETs, no BOOST or BIAS pins, –40°C to 125°C | Higher peak current but no external boost drive - lower efficiency at high VIN/VOUT; no UVLO hysteresis | Choose MPQ4433AGL-A-Z for simplified layout (no BOOST diode/cap) and higher peak current margin; prefer LT3431EFE#PBF where thermal performance at full load is paramount. |
Compared with LT8609S#PBF and MPQ4433AGL-A-Z, the LT3431EFE#PBF uniquely combines 60V input tolerance, BOOST-enabled low-loss switching, BIAS-driven efficiency scaling, and dual-threshold SHDN for robust industrial startup - making it optimal for high-reliability 5V/2A conversion where thermal management and transient resilience are prioritized over footprint size.
Availability
LT3431EFE#PBF is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, portable medical devices, and distributed telecom systems requiring stable component supply with long-term lifecycle assurance.
Supply support for LT3431EFE#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, Inc. (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 LT3431EFE#PBF belongs to Linear's high-voltage monolithic buck regulator product line, designed specifically for rugged industrial and automotive power conversion where input transients, wide VIN range, and thermal reliability are critical system requirements.
FAQ
What is the maximum input voltage rating for the LT3431EFE#PBF?
The LT3431EFE#PBF has an absolute maximum input voltage rating of 60V on the VIN pins (3, 4), with guaranteed operation from 5.5V to 60V. Transient tolerance up to 60V is validated per datasheet specifications, and the device includes internal protection against overvoltage stress on internal circuitry. Always observe the 60V limit to prevent permanent damage to the LT3431EFE#PBF.
How does the BOOST pin function in the LT3431EFE#PBF, and what external components are required?
The BOOST pin (Pin 6) on the LT3431EFE#PBF supplies elevated gate drive to the internal NPN switch, enabling saturation and achieving 0.1Ω effective on-resistance. It requires an external diode (e.g., MMSD914) and capacitor (e.g., 0.22µF ceramic) connected between SW and BOOST. The BOOST voltage must exceed VIN by at least 1.8V to guarantee full switch saturation across temperature and load conditions in the LT3431EFE#PBF.
Can the LT3431EFE#PBF operate without connecting the BIAS pin, and what impact does that have?
Yes, the LT3431EFE#PBF operates fully functional with the BIAS pin (Pin 10) left unconnected - internal bias circuitry then draws power from VIN. However, connecting BIAS to VOUT ≥3V shifts bias current from VIN to the output rail, reducing total input-referred quiescent current by up to 35% at high VIN/VOUT ratios. This BIAS connection directly improves light-load efficiency in the LT3431EFE#PBF and is recommended for 24V→5V or 48V→5V applications.
What protection features does the LT3431EFE#PBF provide during output short-circuit conditions?
The LT3431EFE#PBF implements dual-foldback protection triggered by the FB pin voltage: switching frequency reduces ~5:1 when FB falls below 0.8V, and peak switch current limit folds back when FB drops below 0.6V. These actions collectively limit power dissipation in the LT3431EFE#PBF, external diode, and inductor during sustained short-circuit events - preventing thermal runaway without requiring external circuitry.
Is the LT3431EFE#PBF pin-compatible with other members of the LT3431 family, such as the LT3431IFE#PBF?
Yes, the LT3431EFE#PBF and LT3431IFE#PBF share identical pinout, package outline, and electrical functionality. The only difference is temperature grading: LT3431EFE#PBF is characterized for 0°C to 125°C junction operation (with assured –40°C to 125°C performance), while LT3431IFE#PBF is fully guaranteed over –40°C to 125°C. Both use the same 16-pin TSSOP package and are PCB-interchangeable in the LT3431EFE#PBF footprint.
LT3431EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm 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):
- 5.5V
- Voltage - Input (Max):
- 60V
- Voltage - Output (Min/Fixed):
- 1.219V
- Voltage - Output (Max):
- 55.2V
- Current - Output:
- 3A (Switch)
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT3431EFE#PBF FAQ
1.How can I place an order for LT3431EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3431EFE#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 LT3431EFE#PBF reliable?
The price and inventory of LT3431EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3431EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3431EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3431EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3431EFE#PBF?
LT3431EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3431EFE#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 LT3431EFE#PBF?
For technical support, including LT3431EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3431EFE#PBF requirements.
6.How does Aetrix verify that LT3431EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3431EFE#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 LT3431EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3431EFE#PBF?
All LT3431EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3431EFE#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 LT3431EFE#PBF part is unused and in its original packaging.
Return procedure for LT3431EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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