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Analog Devices Inc. LTC3126EUFD#TRPBF
- Part No.:
- LTC3126EUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3126EUFD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 2.5A 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,785
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Product details
Overview
LTC3126EUFD#TRPBF from Analog Devices (formerly Linear Technology) is a 42V, 2.5A synchronous step-down regulator with integrated no-loss PowerPath™ for seamless dual-input power source management. It supports pin-selectable ideal diode-OR or priority input mode, features 2µA Burst Mode® quiescent current, 200kHz–2.2MHz programmable switching frequency, and operates across 2.4V–42V input to 0.818V–VIN output - enabling use in automotive battery backup, supercapacitor-powered industrial equipment, and uninterruptible power supplies.
For engineers reviewing the LTC3126EUFD#TRPBF datasheet, LTC3126EUFD#TRPBF pinout, LTC3126EUFD#TRPBF application, or LTC3126EUFD#TRPBF equivalent, key selection criteria include dual-input UVLO programmability via VSET1/VSET2, PGOOD/VALID/PRIORITY status indicators, EXTVCC bootstrapping for high-VIN/low-VOUT efficiency, and thermal performance in the 4mm × 5mm QFN package with exposed PGND pad.
Technical Context
The LTC3126EUFD#TRPBF implements current-mode control with 60ns minimum on-time and internal PowerPath™ logic that enables automatic, sub-50µs switchover between VIN1 (priority) and VIN2 without hold-up capacitors. Its dual-input architecture includes independent UVLO comparators with hysteresis, zero-current detection, and open-drain status outputs (VALID1/VALID2/PGOOD/PRIORITY) for full system-level power sequencing visibility.
It integrates two high-side/low-side MOSFET drivers (BST1/COM1 and BST2/COM2), an internal LDO for VCC/PVCC (powered from VIN1, VIN2, or EXTVCC), and a precision 1.000V VREF reference for programming UVLO thresholds. The RT pin sets switching frequency via external resistor, and PWM/SYNC supports both burst-PWM transition control and external clock synchronization.
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 | Up to 2.5A continuous - sufficient for powering FPGA I/O banks, microcontroller cores, or industrial sensor subsystems. |
| Burst Mode IQ | 2µA - enables multi-year operation from energy-harvesting or backup sources with minimal standby drain. |
| Switching Frequency | 200kHz to 2.2MHz (RT-programmable) - allows optimization of size (high-f) vs. EMI/noise (low-f) in space-constrained designs. |
| UVLO Thresholds | Programmable per input (VSET1/VSET2) down to 2.34V fixed threshold - enables precise brown-out response for mixed-chemistry battery systems. |
| PowerPath Switchover | Automatic, no-loss transition between VIN1 and VIN2 - eliminates output rail disturbance and removes need for large hold-up capacitance. |
| Package | 28-lead 4mm × 5mm QFN with exposed PGND pad - provides low θJA (34°C/W) for thermally demanding 2.5A loads in compact layouts. |
Pinout & Package
Package: 28-lead (4mm × 5mm) plastic QFN with exposed thermal pad (Pin 29 = PGND). Requires soldering of exposed pad to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN1 / VIN2 | Kelvin sense inputs | Low-impedance sensing paths for priority/secondary inputs; must be connected directly to respective PVIN pins to avoid UVLO errors. |
| PVIN1 / PVIN2 | Main power inputs | High-current paths for priority and secondary sources; require ≥4.7µF ceramic bypass capacitors to GND. |
| VSET1 / VSET2 | UVLO programming inputs | Analog inputs accepting 0–1V to set corresponding VIN1/VIN2 UVLO thresholds from 0–20V (with 2.34V floor). |
| 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). |
| VALID1 / VALID2 | Open-drain status outputs | Assert low when respective input voltage exceeds programmed UVLO - used for upstream power sequencing or fault logging. |
| PRIORITY | Open-drain indicator | Asserts low only when buck is actively sourcing from VIN1 in priority mode - confirms active input channel. |
| PGOOD | Open-drain output monitor | Asserts low if VOUT deviates >±8.7% from regulation or during disable - critical for system reset coordination. |
| EXTVCC | VCC rail bootstrap input | When ≥3.15V applied, powers internal VCC LDO directly from output rail - reduces quiescent current and improves efficiency at high VIN/low VOUT. |
Key Features
| Feature | Design Value |
|---|---|
| No-loss PowerPath™ switchover | Enables seamless, capacitor-free transition between two inputs - eliminates output droop and simplifies backup power architecture. |
| Programmable dual-input UVLO | VSET1/VSET2 allow independent, resistor-based UVLO tuning per source - supports mixed battery chemistries (LiFePO₄, lead-acid, supercap) in same design. |
| 2µA Burst Mode® quiescent current | Extends runtime in always-on backup systems - e.g., maintains real-time clock and SRAM during main power loss for >10 years on a single supercapacitor. |
| Integrated VREF (1.000V ±1%) | Provides stable, temperature-invariant reference for UVLO dividers and external analog circuitry - eliminates need for external precision reference. |
| External clock synchronization (PWM/SYNC) | Allows deterministic EMI reduction by locking switching frequency to system clock - essential for noise-sensitive data acquisition or RF modules. |
| Thermally enhanced QFN package | Exposed PGND pad and low θJA (34°C/W) enable full 2.5A output in ambient up to 85°C without heatsinking - suitable for sealed industrial enclosures. |
Applications
| Automotive Battery Backup System | Industrial Supercapacitor UPS |
|---|---|
Use Scenario: Maintaining power to telematics ECUs during engine cranking or alternator failure using 12V automotive battery (VIN1) and 4.2–24V Li-ion backup (VIN2). IC Role / Device Role / Timing Role: Dual-input buck controller managing priority switchover and providing regulated 3.3V/2.5A to MCU and CAN transceiver. Use Value: Sub-50µs switchover prevents brownout resets; programmable UVLO avoids false triggers during load-dump transients. | Use Scenario: Providing uninterrupted 5V/2A power to PLC I/O modules during AC mains failure, using supercapacitor bank (VIN2) as backup to 24V DC supply (VIN1). IC Role / Device Role / Timing Role: Synchronous step-down regulator with PowerPath™ ensuring zero-interruption transition and monitoring input validity via VALID2. Use Value: 2µA Burst Mode IQ extends supercap lifetime; EXTVCC bootstrapping achieves >92% efficiency at 24V→5V conversion. |
| Portable Test Equipment Power | Uninterruptible Sensor Node |
Use Scenario: Powering handheld oscilloscope front-end ADCs and FPGA from either USB-C PD (VIN1) or removable LiPo pack (VIN2), with priority given to USB when present. IC Role / Device Role / Timing Role: Dual-input PMIC delivering stable 1.8V/2.5A and 3.3V/2.5A rails while indicating active source via PRIORITY and VALID1 signals. Use Value: Pin-selectable mode eliminates firmware dependency; 60ns min on-time supports high VIN/low VOUT ratios required for USB-C PD input. | Use Scenario: Enabling long-life remote environmental sensor node powered by solar-charged LiFePO₄ (VIN1) with supercapacitor (VIN2) for night/cloud operation. IC Role / Device Role / Timing Role: Ultra-low-IQ buck converter maintaining 3.3V rail during weeks of darkness, using VSET1 to set 2.5V UVLO for LiFePO₄ end-of-discharge. Use Value: 1µA shutdown current and programmable UVLO prevent deep discharge damage; PGOOD enables graceful MCU sleep/wake coordination. |
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 |
|---|---|---|---|
| LTC3122IUFD#TRPBF | Lower 36V max input, 1.5A output, no EXTVCC pin, fixed 2.34V UVLO (no VSET programming) | Suitable only for lower-power, non-automotive applications where UVLO flexibility and high-VIN tolerance are not required | Select when cost sensitivity outweighs programmability and 42V transient immunity needs |
| TPS63802DLAR | Single-input buck-boost, 2.5A, 1.8V–5.5V output, no dual-input arbitration or PowerPath™ logic | Cannot replace LTC3126EUFD#TRPBF in true dual-source backup architectures - lacks VALID/PRIORITY signaling and seamless switchover | Consider only for single-rail, wide-VIN applications where input redundancy is unnecessary |
Compared with LTC3122IUFD#TRPBF, the LTC3126EUFD#TRPBF adds 6V higher input rating, 1A higher output current, programmable UVLO, and EXTVCC efficiency boost - making it uniquely suited for automotive and industrial backup systems. Against TPS63802DLAR, it provides dedicated dual-input control logic and status signaling absent in buck-boost topologies.
Availability
LTC3126EUFD#TRPBF is available at Aetrix Electronics and suitable for automotive battery backup systems, industrial supercapacitor UPS units, and portable test equipment requiring stable component supply across extended temperature ranges (–40°C to 125°C).
Supply support for LTC3126EUFD#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 continues its legacy of high-performance power management ICs with precision analog integration and robust reliability.
The LTC3126EUFD#TRPBF belongs to Linear's PowerPath™ family of dual-input power managers, designed specifically for mission-critical backup power applications where seamless, no-loss transitions between primary and secondary sources are mandatory.
FAQ
What is the maximum input voltage rating for the LTC3126EUFD#TRPBF?
The LTC3126EUFD#TRPBF has an absolute maximum input voltage rating of 42V on PVIN1, PVIN2, VIN1, and VIN2 pins. Its operational input range is 2.4V to 42V after startup, making it suitable for automotive 24V systems with load-dump transients and industrial 36V nominal supplies. Exceeding 42V risks permanent damage per Absolute Maximum Ratings.
How does the LTC3126EUFD#TRPBF achieve seamless switchover between two input sources?
The LTC3126EUFD#TRPBF uses internal PowerPath™ logic with fast UVLO comparators and zero-current detection to switch between VIN1 and VIN2 in under 50µs without output disturbance. It requires no hold-up capacitors because the control loop maintains regulation during transition - confirmed in Typical Application TA01b waveform plots showing clean VOUT during automotive input unplugging.
Can the LTC3126EUFD#TRPBF operate with only one input source connected?
Yes - the LTC3126EUFD#TRPBF functions as a standard synchronous buck converter with a single input. If only VIN1 is connected (and valid), DIODE pin state determines behavior: in priority mode (DIODE low), it operates normally; in ideal diode-OR mode (DIODE high), it still regulates but VALID2 remains high (not driven), and PRIORITY reflects VIN1 usage. No damage occurs with one input floating or disconnected.
What is the purpose of the EXTVCC pin on the LTC3126EUFD#TRPBF?
The EXTVCC pin on the LTC3126EUFD#TRPBF allows bootstrapping the internal VCC LDO from the output rail instead of VIN1/VIN2. When pulled to ≥3.15V, it reduces quiescent current and improves efficiency - especially critical in high-input/low-output applications like 24V→3.3V conversion. Leaving EXTVCC open defaults to VIN1/VIN2 sourcing, which increases IQ at light loads.
Does the LTC3126EUFD#TRPBF support external frequency synchronization?
Yes - the PWM/SYNC pin on the LTC3126EUFD#TRPBF accepts an external clock signal (200kHz–2.2MHz) to synchronize switching. When synchronized, the device operates exclusively in PWM mode (Burst Mode disabled), enabling deterministic EMI filtering and noise reduction in sensitive mixed-signal systems. Clock edges must meet specified pulse width requirements (≥100ns high, ≥150ns low).
LTC3126EUFD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LTC3126EUFD#TRPBF FAQ
1.How can I place an order for LTC3126EUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3126EUFD#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 LTC3126EUFD#TRPBF reliable?
The price and inventory of LTC3126EUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3126EUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3126EUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3126EUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3126EUFD#TRPBF?
LTC3126EUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3126EUFD#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 LTC3126EUFD#TRPBF?
For technical support, including LTC3126EUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3126EUFD#TRPBF requirements.
6.How does Aetrix verify that LTC3126EUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3126EUFD#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 LTC3126EUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3126EUFD#TRPBF?
All LTC3126EUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3126EUFD#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 LTC3126EUFD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3126EUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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