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Analog Devices Inc. LTC3126HFE#TRPBF
- Part No.:
- LTC3126HFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3126HFE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 2.5A 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,860
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Product details
Overview
LTC3126HFE#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 modes, programmable UVLO thresholds (2.34V–20V), and operates across 2.4V–42V input range to deliver 0.818V–VIN output. Used in automotive battery backup systems where transient immunity and automatic switchover are critical.
For engineers reviewing the LTC3126HFE#TRPBF datasheet, LTC3126HFE#TRPBF pinout, LTC3126HFE#TRPBF application, or LTC3126HFE#TRPBF equivalent, key selection factors include dual-input UVLO programmability, 2µA Burst Mode quiescent current, 200kHz–2.2MHz frequency setting via RT resistor, thermal performance at 150°C junction temperature, and TSSOP-28 package compatibility with industrial/automotive PCB layouts.
Technical Context
The LTC3126HFE#TRPBF implements current-mode control with 60ns minimum on-time and fixed-frequency PWM operation, synchronizable to external clock. Its internal PowerPath architecture uses independent VIN1/VIN2 valid comparators, priority channel logic, and active input indicators to manage transitions without hold-up capacitors.
It integrates two high-side (200mΩ) and two low-side (70mΩ) MOSFETs, supports EXTVCC bootstrapping for efficiency optimization, and features dedicated BST1/COM1 and BST2/COM2 charge pump rails for gate drive. The device maintains regulation down to 2.4V input and delivers up to 2.5A continuous output current with thermal shutdown protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.4V to 42V - supports automotive transients (42V), supercapacitor discharge, and multicell battery stacks without external pre-regulation. |
| Output Current | 2.5A continuous - sufficient for powering microcontrollers, FPGAs, and communication ICs in backup power rails. |
| Burst Mode IQ | 2µA - enables multi-year battery life in always-on industrial monitoring systems with light-load duty cycles. |
| Switching Frequency | 200kHz to 2.2MHz - adjustable via RT resistor; higher frequencies allow smaller inductors and faster transient response. |
| UVLO Threshold Range | 2.34V to 20V per input - programmable via VSET1/VSET2 pins using VREF divider, enabling precise power-source handoff control. |
| Junction Temp Range | –40°C to +150°C - qualified for under-hood automotive and high-temperature industrial environments. |
| Package | 28-Lead TSSOP (4.4mm) - thermally enhanced with exposed PGND pad; compatible with standard reflow profiles and automated assembly. |
Pinout & Package
Package: 28-Lead Plastic TSSOP (4.4mm wide), thermally enhanced with exposed PGND pad (Pin 29) requiring solder connection to PCB ground plane for optimal thermal performance (θJA = 30°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN1 / Pin 28 | Priority Input Kelvin Sense | Low-impedance sensing path for PVIN1; must be connected directly to PVIN1 capacitor to minimize voltage drop during switchover. |
| VIN2 / Pin 1 | Secondary Input Kelvin Sense | Low-impedance sensing path for PVIN2; ensures accurate UVLO detection independent of PCB trace resistance. |
| PVIN1 / Pin 27 | Priority Input Power Rail | Main power entry for primary source (e.g., automotive battery); requires ≥4.7µF ceramic bypass to PGND. |
| PVIN2 / Pin 16 | Secondary Input Power Rail | Main power entry for backup source (e.g., supercapacitor); requires ≥4.7µF ceramic bypass to PGND. |
| DIODE / Pin 26 | Mode Selection Input | High = ideal diode-OR (auto-select highest valid input); Low = priority mode (VIN1 first, fallback to VIN2 only on UVLO). |
| PRIORITY / Pin 15 | Open-Drain Status Output | Asserted low when buck is operating from VIN1; used for system-level power-path monitoring and fault logging. |
| VALID1 / Pin 3 | Open-Drain Input Valid Flag | Asserted low when VIN1 > programmed UVLO threshold; enables real-time validation of primary source health. |
| VALID2 / Pin 4 | Open-Drain Input Valid Flag | Asserted low when VIN2 > programmed UVLO threshold; allows independent status reporting for backup source. |
| PGOOD / Pin 14 | Open-Drain Output Regulation Flag | Asserted low if VOUT deviates >±8.7% from FB setpoint or converter is disabled; critical for safe system startup sequencing. |
| ENA / Pin 17 | Enable Control Input | Active-high logic input; pulling low disables all switching, UVLO comparators, and VREF, reducing total system IQ to 1µA. |
| FB / Pin 12 | Feedback Voltage Input | Resistor divider sets output voltage (0.818V reference); routing must avoid SW/BST noise coupling to maintain stability. |
| RT / Pin 13 | Frequency Programming Node | Resistor to GND sets fSW per RT = 33.2MHz/fSW (kΩ); enables optimization between efficiency, size, and EMI. |
| VSET1 / Pin 8 | VIN1 UVLO Programming Input | Voltage (0–1V) programs VIN1 UVLO threshold (0–20V); grounded to enable fixed 2.34V threshold. |
| VSET2 / Pin 9 | VIN2 UVLO Programming Input | Voltage (0–1V) programs VIN2 UVLO threshold (0–20V); grounded to enable fixed 2.34V threshold. |
| VREF / Pin 10 | 1.000V Precision Reference | Stable, temperature-compensated reference for VSET dividers; max load 1mA; unused pin must tie to VCC. |
| EXTVCC / Pin 7 | VCC Bootstrap Input | When ≥3.15V applied, powers internal VCC rail directly-reducing dropout loss and improving light-load efficiency. |
| VCC / Pin 5, PVCC / Pin 6 | Internal LDO Output & Supply | Regulated ~4.2V supply for control circuitry; must be shorted together and bypassed with ≥4.7µF to PGND. |
| SW / Pin 20, Pin 23 | Power Switch Node | Connects to inductor; carries full switching current; requires low-inductance layout and Kelvin return to PGND. |
| BST1 / Pin 18, COM1 / Pin 19 | Charge Pump for HS1 Gate Drive | 0.1µF capacitor between BST1–COM1 generates gate drive above PVIN1 for high-side MOSFET. |
| BST2 / Pin 25, COM2 / Pin 24 | Charge Pump for HS2 Gate Drive | 0.1µF capacitor between BST2–COM2 generates gate drive above PVIN2 for second high-side MOSFET. |
| GND / Pin 11 | Signal Ground Reference | Reference for FB, RT, VREF, and logic inputs; must connect to clean analog ground separate from PGND planes. |
| PGND / Pins 21, 22, 29 | Power Ground Return | High-current return path for SW, BST, and input/output capacitors; exposed pad (Pin 29) must be soldered to PCB ground plane. |
| PWM/SYNC / Pin 2 | Mode Control & Clock Input | High = forced PWM; Low = Burst Mode; external clock input synchronizes switching to system timing domain. |
Key Features
| Feature | Design Value |
|---|---|
| No-loss PowerPath™ architecture | Eliminates need for hold-up capacitors by enabling sub-50µs switchover between VIN1 and VIN2 without output droop. |
| Programmable dual-input UVLO | VSET1/VSET2 pins allow independent, resistor-programmed UVLO thresholds (2.34V–20V) per input for precise source handoff control. |
| 2.5A continuous output with thermal protection | Integrated MOSFETs and thermal shutdown ensure reliable operation at full load up to 150°C junction temperature. |
| 2µA Burst Mode quiescent current | Extends battery life in always-on applications such as telematics and remote sensors by minimizing standby power draw. |
| EXTVCC bootstrapping capability | Connecting EXTVCC to VOUT reduces VCC dropout loss, improving efficiency by up to 3% in high-VIN/low-VOUT configurations. |
| 200kHz–2.2MHz programmable frequency | RT resistor selection enables optimization for EMI compliance, inductor size, or transient response without changing layout. |
Applications
| Automotive Battery Backup Systems | Industrial Uninterruptible Power Supplies |
|---|---|
Use Scenario: Maintaining 3.3V/2.5A power to ADAS controller during cold-crank (5V–10V) or load-dump (42V) events while switching between main battery and supercapacitor bank. IC Role / Device Role / Timing Role: Dual-input synchronous buck regulator with priority mode, providing regulated output and real-time VALID1/PRIORITY status signals for system-level fault recovery. Use Value: Eliminates hold-up capacitors and enables <50µs switchover, preventing brownout resets during engine start-stop cycles. | Use Scenario: Providing continuous 5V/2A power to PLC I/O modules during AC mains failure, using Li-ion battery as backup source. IC Role / Device Role / Timing Role: Seamless transition controller managing priority (mains) and secondary (battery) inputs with programmable UVLO to prevent premature battery discharge. Use Value: Reduces system BOM cost by replacing discrete OR-ing FETs and supervisory ICs with single-chip solution featuring PGOOD and VALID outputs. |
| Portable Test Equipment Power | Supercapacitor-Based Energy Harvesting |
Use Scenario: Powering handheld oscilloscope with 12V/1.5A output from either 19V wall adapter or 3.7V LiPo battery, maintaining stable rail during hot-swap. IC Role / Device Role / Timing Role: Ideal diode-OR mode regulator that automatically selects highest valid input, with ENA-controlled shutdown for zero-system leakage. Use Value: Enables true plug-and-play operation without manual input selection; 1µA shutdown current extends field-deployed battery life. | Use Scenario: Charging and regulating power from solar-harvested supercapacitor stack (2.5V–35V) to supply 3.3V/500mA to wireless sensor node. IC Role / Device Role / Timing Role: Wide-input buck converter with Burst Mode operation, supporting ultra-low-power sleep states and fast wake-up from energy harvesting events. Use Value: 2µA quiescent current minimizes self-discharge, extending supercapacitor hold-up time by >3× versus conventional regulators. |
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 | 28-pin QFN, 42V/2A, no PowerPath, single-input only, 3.5µA IQ | Lacks dual-input switchover, UVLO programming, and PRIORITY/VALID outputs; suitable only for single-source designs. | Select only if dual-input functionality is unnecessary and QFN thermal performance is preferred over TSSOP. |
| MAX20406ATGB/VY+ | 20V/6A, integrated FETs, I²C-configurable UVLO, 2.5µA IQ, 16-pin TQFN | Lower max input voltage (20V), no EXTVCC bootstrap, requires digital configuration; lacks open-drain status outputs. | Choose when I²C programmability and higher current are needed, but automotive 42V transient immunity is not required. |
Compared with LTC3122IUFD#TRPBF and MAX20406ATGB/VY+, the LTC3126HFE#TRPBF uniquely combines 42V input rating, hardware-selectable dual-input modes, 2.5A output, and dedicated status signaling in a 150°C-rated TSSOP package-making it the only option for high-reliability automotive and industrial backup power where analog control and thermal robustness are mandatory.
Availability
LTC3126HFE#TRPBF is available at Aetrix Electronics and suitable for automotive battery backup systems, industrial uninterruptible power supplies, and portable test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3126HFE#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 precision analog and power management portfolio. Linear's legacy design rigor ensures high reliability, tight parametric tolerances, and extensive automotive qualification.
The LTC3126 product line was engineered specifically for mission-critical dual-input power systems in automotive, industrial, and aerospace applications-emphasizing seamless switchover, wide input range, and robust thermal performance without compromising ease of use.
FAQ
What is the maximum junction temperature specification for the LTC3126HFE#TRPBF?
The LTC3126HFE#TRPBF is specified for operation from –40°C to +150°C junction temperature. This H-grade rating is validated per manufacturer datasheet Note 2 and distinguishes it from E-grade (–40°C to 125°C) and I-grade variants. Thermal design must ensure θJA ≤ 30°C/W using the exposed PGND pad soldered to PCB ground plane.
How does the LTC3126HFE#TRPBF implement seamless switchover between VIN1 and VIN2?
The LTC3126HFE#TRPBF achieves sub-50µs switchover using internal no-loss PowerPath™ architecture with independent VIN1/VIN2 valid comparators, priority logic, and fast gate drivers. When VIN1 drops below its UVLO threshold, the device immediately enables the VIN2 path without output droop-eliminating need for hold-up capacitors. This behavior is confirmed in Typical Application Figure TA01b.
Can the LTC3126HFE#TRPBF operate with only one input source connected?
Yes, the LTC3126HFE#TRPBF functions correctly with only VIN1 or only VIN2 connected. In priority mode (DIODE = low), if VIN1 is absent or invalid, the device will attempt to operate from VIN2 if valid. In ideal diode-OR mode (DIODE = high), it selects the highest valid input-so with only one source present, it operates from that source. Unused inputs should be left floating or tied to GND through appropriate RC networks per datasheet recommendations.
What is the purpose of the EXTVCC pin on the LTC3126HFE#TRPBF?
The EXTVCC pin on the LTC3126HFE#TRPBF allows bootstrapping the internal VCC LDO rail from the buck output voltage instead of VIN1/VIN2. When EXTVCC ≥ 3.15V, it powers the control circuitry directly-reducing VCC dropout loss and improving light-load efficiency by up to 3%. This is especially beneficial in high-input/low-output applications like 24V-to-3.3V conversion.
Does the LTC3126HFE#TRPBF support synchronization to an external clock?
Yes, the LTC3126HFE#TRPBF supports external clock synchronization via the PWM/SYNC pin. Applying a 200kHz–2.2MHz CMOS-compatible clock signal forces fixed-frequency PWM operation and disables Burst Mode. This enables EMI reduction through frequency dithering or alignment with system timing domains, as detailed in the Electrical Characteristics table and Pin Functions section.
LTC3126HFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) 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 ~ 150°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSSOP-EP
LTC3126HFE#TRPBF FAQ
1.How can I place an order for LTC3126HFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3126HFE#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 LTC3126HFE#TRPBF reliable?
The price and inventory of LTC3126HFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3126HFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3126HFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3126HFE#TRPBF transactions.
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LTC3126HFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3126HFE#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 LTC3126HFE#TRPBF?
For technical support, including LTC3126HFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3126HFE#TRPBF requirements.
6.How does Aetrix verify that LTC3126HFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3126HFE#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 LTC3126HFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3126HFE#TRPBF?
All LTC3126HFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3126HFE#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 LTC3126HFE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3126HFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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