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Analog Devices Inc. LTC3126MPFE#PBF
- Part No.:
- LTC3126MPFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3126MPFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 2.5A 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,529
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Product details
Overview
LTC3126MPFE#PBF from Analog Devices (formerly Linear Technology) is a 42V, 2.5A synchronous step-down regulator with no-loss PowerPath™ supporting seamless dual-input power source selection. It operates across 2.4V–42V input, delivers up to 2.5A continuous output, features pin-selectable priority/ideal diode-OR modes, 2µA Burst Mode quiescent current, and supports automotive battery backup, supercapacitor hold-up, and uninterruptible power supply applications.
For engineers reviewing the LTC3126MPFE#PBF datasheet, LTC3126MPFE#PBF pinout, LTC3126MPFE#PBF application, or LTC3126MPFE#PBF equivalent, key selection considerations include its –55°C to 150°C extended temperature rating, TSSOP-28 package with exposed PGND pad, programmable UVLO thresholds via VSET1/VSET2, 200kHz–2.2MHz frequency programming, and dual-input status indicators (VALID1/VALID2/PRIORITY/PGOOD).
Technical Context
The LTC3126MPFE#PBF implements current-mode control with 60ns minimum on-time, enabling stable operation at high VIN/VOUT ratios and low duty cycles. Its internal PowerPath architecture uses fast-acting comparators and zero-current detection to enable sub-50µs automatic switchover between VIN1 (priority) and VIN2 (backup), eliminating hold-up capacitors.
It integrates dual high-side (200mΩ) and low-side (70mΩ) MOSFETs, a precision 818mV feedback reference with ±0.8% initial accuracy, and independent input validation logic with hysteresis. The device supports external synchronization, programmable switching frequency via RT resistor, and EXTVCC bootstrapping for improved efficiency in high-VIN/low-VOUT configurations.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.4V to 42V - supports automotive transients (42V), supercapacitors, multicell batteries, and unregulated adapters without external protection. |
| Output Current | 2.5A continuous - sufficient for powering FPGA I/O banks, microcontroller cores, or industrial sensors directly. |
| Burst Mode IQ | 2µA - enables multi-year battery life in always-on monitoring systems with light-load operation. |
| Switching Frequency | 200kHz to 2.2MHz - adjustable via RT resistor; allows optimization of size (high-freq) vs. efficiency (mid-freq) and EMI compliance. |
| Feedback Reference | 818mV ±0.8% - enables accurate output regulation from 0.818V up to VIN; supports precise point-of-load scaling. |
| Operating Temp Range | –55°C to +150°C - fully tested and guaranteed for aerospace, downhole, and military-grade thermal environments. |
| UVLO Thresholds | Programmable via VSET1/VSET2 (0–1V → 0–20V) with fixed 2.34V fallback - ensures reliable startup and brownout recovery across diverse input sources. |
Pinout & Package
Package: 28-Lead Plastic TSSOP (4.4mm wide), thermally enhanced with exposed PGND pad (Pin 29) requiring PCB soldering for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN1 / VIN2 | Kelvin sense inputs | Low-impedance sensing nodes for priority/secondary inputs; must be shorted to respective PVIN pins to minimize voltage drop errors. |
| PVIN1 / PVIN2 | Main power inputs | High-current paths for priority (VIN1) and backup (VIN2) sources; require ≥4.7µF ceramic bypassing to ground. |
| VALID1 / VALID2 | Open-drain status outputs | Indicate real-time validity of each input above programmed UVLO; float when ENA = low, enabling system-level fault isolation. |
| PRIORITY | Open-drain mode indicator | Asserts low only when operating from VIN1 in priority mode; provides direct visibility into active input channel for diagnostics. |
| DIODE | Mode select logic input | High = ideal diode-OR (auto-select highest valid input); Low = priority mode (VIN1 first, fallback to VIN2 only on undervoltage). |
| VSET1 / VSET2 | UVLO programming inputs | Accept 0–1V analog voltage to set corresponding VIN1/VIN2 UVLO threshold from 0–20V; grounded for fixed 2.34V threshold. |
| EXTVCC | VCC rail bootstrap input | When ≥3.15V applied, powers internal VCC LDO directly from output rail-reducing quiescent current and improving efficiency at high VIN/low VOUT. |
| PGND (Pins 21,22,29) | Power ground terminals | Multiple low-inductance connections to system ground; exposed pad (Pin 29) must be soldered to maximize thermal dissipation (θJA = 30°C/W). |
Key Features
| Feature | Design Value |
|---|---|
| No-loss PowerPath™ switchover | Enables <50µs seamless transition between inputs without output droop or hold-up capacitors-critical for fail-safe power systems. |
| Pin-selectable dual-input modes | DIODE pin configures either priority (VIN1-first) or ideal diode-OR (highest valid input) behavior-no firmware or external logic required. |
| Programmable UVLO with hysteresis | VSET1/VSET2 allow independent, precise UVLO setting per input (e.g., 12V±0.5V for automotive, 3.0V±0.1V for Li-ion), preventing oscillation during brownouts. |
| 200kHz–2.2MHz frequency tuning | RT resistor sets exact switching frequency to avoid noise-sensitive bands (e.g., AM radio) or match system clock domains. |
| Integrated status signaling | Four dedicated open-drain outputs (VALID1/VALID2/PRIORITY/PGOOD) provide complete real-time power system visibility for host MCU monitoring. |
| –55°C to +150°C guaranteed operation | Full electrical characterization and testing across this range ensures reliability in extreme environments-no derating required up to 150°C junction. |
Applications
| Automotive Battery Backup | Industrial Supercapacitor Hold-Up |
|---|---|
Use Scenario: Maintaining 3.3V/2.5A system power during engine cranking (VIN drops to 4.2V) while primary 12V rail collapses. IC Role / Device Role / Timing Role: LTC3126MPFE#PBF acts as dual-input buck controller, sourcing power from backup battery when main rail falls below 6.5V (programmed via VSET1). Use Value: Eliminates need for large electrolytic hold-up capacitors; achieves <50µs switchover with no output glitch, preserving CAN/LIN bus integrity. | Use Scenario: Providing uninterrupted 5V/2A power to PLC I/O modules during AC mains failure, using 2.7V/10F supercapacitor stack as backup source. IC Role / Device Role / Timing Role: LTC3126MPFE#PBF regulates supercapacitor discharge (2.4V–42V input range) while prioritizing main 24V rail; switches automatically on AC loss. Use Value: Enables compact, maintenance-free backup with 2µA Burst Mode IQ-extending supercapacitor runtime by >3× versus standard buck controllers. |
| Uninterruptible Power Supply (UPS) | Portable Test Equipment |
Use Scenario: Dual-input UPS for telecom edge routers accepting both 48V DC plant power and 24V PoE+ backup, delivering regulated 12V/2A output. IC Role / Device Role / Timing Role: LTC3126MPFE#PBF serves as primary DC-DC stage with priority on 48V input; transitions to 24V PoE+ within 30µs if primary fails. Use Value: Provides true zero-downtime power with PGOOD/VALID signals enabling upstream firmware to log fault events and initiate graceful shutdown if both inputs fail. | Use Scenario: Portable handheld oscilloscope powered by single-cell Li-ion (3.0–4.2V) or USB-C PD (5–20V), requiring stable 1.8V/2.5A core voltage. IC Role / Device Role / Timing Role: LTC3126MPFE#PBF operates in ideal diode-OR mode, selecting highest valid input; uses EXTVCC bootstrapping to maintain 95% efficiency at 20V→1.8V conversion. Use Value: Extends battery life via 2µA no-load IQ and enables universal input compatibility without manual switching or external multiplexers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-input buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3126HFE#PBF | Same silicon, rated for –40°C to +150°C (not –55°C); lower cold-start capability; identical pinout and features. | Suitable for industrial environments where –55°C operation is not required; lacks extended low-temp qualification. | Select LTC3126MPFE#PBF when operation below –40°C (e.g., aerospace, polar instrumentation) is mandatory. |
| LTC3126IUFD#PBF | QFN-28 package (4mm × 5mm); higher thermal resistance (θJA = 34°C/W vs. 30°C/W); same –40°C to +125°C rating. | Better for space-constrained layouts; less suitable for sustained 2.5A loads in high ambient temperatures without aggressive PCB copper. | Choose LTC3126MPFE#PBF for high-reliability, high-temperature, or extended-cold applications where TSSOP mechanical robustness and thermal performance are prioritized. |
Compared with LTC3126HFE#PBF and LTC3126IUFD#PBF, the LTC3126MPFE#PBF uniquely guarantees full electrical performance from –55°C to +150°C in the thermally optimized TSSOP package-making it the only option qualified for mission-critical cold-start and sustained high-temperature operation without derating.
Availability
LTC3126MPFE#PBF is available at Aetrix Electronics and suitable for automotive battery backup, industrial supercapacitor hold-up, and uninterruptible power supply applications requiring stable component supply across extreme temperature ranges and long product lifecycles.
Supply support for LTC3126MPFE#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 and military-grade qualification standards.
The LTC3126 product line was designed specifically for seamless dual-input power systems in harsh environments-targeting automotive infotainment, avionics, downhole tools, and industrial UPS where reliability across –55°C to +150°C is non-negotiable.
FAQ
What is the guaranteed operating temperature range for the LTC3126MPFE#PBF?
The LTC3126MPFE#PBF is fully tested and guaranteed over –55°C to +150°C junction temperature. This extended range exceeds standard automotive (–40°C to +125°C) and industrial specifications, making it suitable for aerospace, downhole, and military applications where cold-start reliability and high-temperature endurance are critical. All electrical parameters in the datasheet apply across this full range.
How does the LTC3126MPFE#PBF handle automatic switchover between two input sources?
The LTC3126MPFE#PBF uses internal comparators and zero-current detection to achieve sub-50µs switchover between VIN1 and VIN2. In priority mode (DIODE = low), it operates from VIN1 until its voltage falls below the programmed UVLO threshold, then instantly transfers load to VIN2. In ideal diode-OR mode (DIODE = high), it continuously selects the highest valid input-ensuring uninterrupted output without hold-up capacitors or external circuitry.
Can the LTC3126MPFE#PBF be synchronized to an external clock?
Yes, the LTC3126MPFE#PBF supports external synchronization via the PWM/SYNC pin. When an external clock signal (200kHz–2.2MHz) is applied, the device locks to that frequency and operates in forced PWM mode-disabling Burst Mode. This feature enables EMI reduction through frequency dithering or alignment with system clocks, and ensures deterministic timing in synchronized power architectures.
What is the purpose of the EXTVCC pin on the LTC3126MPFE#PBF?
EXTVCC on the LTC3126MPFE#PBF bootstraps the internal VCC LDO rail. When driven to ≥3.15V (e.g., from the output rail), it powers the control circuitry directly-reducing quiescent current and improving efficiency, especially in high-VIN/low-VOUT applications like 24V→3.3V conversion. If left open, VCC is powered from VIN1/VIN2, increasing no-load current but simplifying layout.
Does the LTC3126MPFE#PBF require external MOSFETs or is it a complete buck solution?
The LTC3126MPFE#PBF is a complete synchronous buck converter with integrated high-side (200mΩ) and low-side (70mΩ) MOSFETs. No external power switches are needed-only an inductor, output capacitor, input bypass capacitors, and optional RT resistor for frequency setting. This integration reduces BOM count, PCB area, and design risk while maintaining 2.5A continuous output capability.
LTC3126MPFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-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):
- 2.4V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 0.818V
- Voltage - Output (Max):
- 42V
- Current - Output:
- 2.5A
- Frequency - Switching:
- 200kHz ~ 2.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSSOP-EP
LTC3126MPFE#PBF FAQ
1.How can I place an order for LTC3126MPFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3126MPFE#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 LTC3126MPFE#PBF reliable?
The price and inventory of LTC3126MPFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3126MPFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3126MPFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3126MPFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3126MPFE#PBF?
LTC3126MPFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3126MPFE#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 LTC3126MPFE#PBF?
For technical support, including LTC3126MPFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3126MPFE#PBF requirements.
6.How does Aetrix verify that LTC3126MPFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3126MPFE#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 LTC3126MPFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3126MPFE#PBF?
All LTC3126MPFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3126MPFE#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 LTC3126MPFE#PBF part is unused and in its original packaging.
Return procedure for LTC3126MPFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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