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Analog Devices Inc. LT1071IT#PBF
- Part No.:
- LT1071IT#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- TO-220-5
- Datasheet:
-
LT1071IT#PBF.pdf
- Description:
- IC REG BUCK BST ADJ 2.5A TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:106
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Product details
Overview
LT1071IT#PBF from Analog Devices (formerly Linear Technology) is a monolithic 2.5A high-efficiency current-mode switching regulator IC in a 5-pin TO-220 package. It operates across 3V–60V input, delivers up to 50W output power, features internal 2.5A switch with 0.3Ω typical RDS(on), 40kHz fixed-frequency operation, and supports buck, boost, flyback, forward, inverting, and Cuk topologies. It is used in off-line converters, battery upconverters, and isolated dual-rail supplies.
For engineers reviewing the LT1071IT#PBF datasheet, LT1071IT#PBF pinout, LT1071IT#PBF application, or LT1071IT#PBF equivalent, key selection criteria include its 2.5A switch current limit, flyback regulation mode enabling fully floating outputs without optocouplers, shutdown current of 50µA, and compatibility with wide-input industrial power supplies requiring robust overload protection and minimal external components.
Technical Context
The LT1071IT#PBF implements current-mode control: switch duty cycle is directly set by sensed switch current rather than output voltage feedback, delivering fast line transient response and inherent pulse-by-pulse overcurrent protection. Its adaptive antisaturation driver minimizes switch turn-off delay and driver dissipation across load-current range.
It integrates a 1.24V bandgap reference, error amplifier (4400 µmho transconductance), 40kHz oscillator, shutdown circuitry, and flyback regulation mode-activated by pulling FB below 0.45V-which replaces main error amplifier with dedicated flyback amplifier for transformer-coupled isolated output control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 2.5A typical (guaranteed ≥2.5A at TJ ≥25°C, ≤50% duty cycle); enables safe 50W operation without external MOSFET. |
| Input Voltage Range | 3V to 60V; supports wide-range industrial, automotive, and off-line inputs without pre-regulation. |
| Quiescent Supply Current | 6mA typical; ensures low no-load power loss in always-on systems. |
| Shutdown Current | 50µA typical; allows ultra-low standby consumption for energy-sensitive applications. |
| Reference Voltage | 1.244V ±20mV (25°C); sets output accuracy in standard buck/boost configurations via resistive divider. |
| Switch "On" Resistance | 0.30Ω typical (measured at ISW = 2A); determines conduction loss and thermal rise under full load. |
| Operating Junction Temp | –40°C to 125°C (Industrial grade); validated for harsh environments without derating. |
| Switching Frequency | 40kHz ±5kHz; balances EMI, magnetics size, and efficiency for medium-power designs. |
Pinout & Package
LT1071IT#PBF uses a 5-lead plastic TO-220 (T package) with exposed tab electrically connected to GND. The package provides low thermal resistance (θJA = 75°C/W) and mechanical robustness for high-power switching applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply connection | Accepts 3V–60V unregulated DC; must be decoupled near pin with ≥1000µF bulk capacitance. |
| VSW | Switch collector/drain node | Connects to primary winding of inductor/transformer; handles high di/dt and 65V max flyback spikes. |
| GND | Power and signal ground reference | Common return for internal circuits, switch emitter/source, and external catch diode cathode. |
| FB | Feedback input / mode select | At 1.244V sets output voltage; pulled low (<0.45V) enables flyback regulation mode for isolated outputs. |
| VC | Error amplifier output / control interface | Provides gm-amplifier output voltage (0.9–2.0V normal); used for compensation, soft-start, current limit adjustment, and shutdown. |
Key Features
| Feature | Design Value |
|---|---|
| Flyback regulation mode | Enables fully floating, optocoupler-free isolated outputs by regulating flyback pulse amplitude referenced to VIN. |
| Self-protected overload handling | Integrated current-limit, thermal shutdown, and adaptive antisaturation drive prevent latch-up or destruction during short-circuit events. |
| Wide topology support | Operates in buck, boost, flyback, forward, inverting, and Cuk configurations using same IC and minimal external parts. |
| Low-component-count design | Requires only inductor, catch diode, output capacitor, and two feedback resistors for basic buck/boost-no external sense resistor or timing caps. |
| High-voltage tolerance | 65V switch breakdown rating and ±15V FB pin transient rating allow direct use in 48V telecom and 36V automotive systems. |
| Adaptive antisaturation drive | Dynamically adjusts gate/base drive to minimize saturation time and driver losses across 0–2.5A load range. |
Applications
| Off-Line AC/DC Converter | Battery-Powered Upconverter |
|---|---|
|
Use Scenario: Converting rectified 85–265VAC to regulated 12V/2A for industrial control modules. IC Role / Device Role / Timing Role: Primary-side flyback controller with integrated 2.5A switch and self-synchronized regulation-eliminates optocoupler and TL431. Use Value: Achieves >82% efficiency at full load with <150mV output ripple, reducing heatsink requirements and BOM count by 4 components vs. controller+MOSFET solution. |
Use Scenario: Boosting 12V lead-acid battery to 24V for vehicle-mounted instrumentation. IC Role / Device Role / Timing Role: High-current boost regulator operating in continuous conduction mode with 40kHz fixed frequency. Use Value: Delivers stable 24V/2A output down to 10.5V input (cold-crank condition), maintaining regulation without external current-sense amplifiers. |
| Isolated Dual-Rail Supply | Industrial Sensor Excitation |
|
Use Scenario: Generating ±15V rails from 24V DC for precision op-amp front-ends in data acquisition systems. IC Role / Device Role / Timing Role: Flyback regulator with center-tapped secondary; FB pin configured for floating output regulation. Use Value: Provides 0.5% cross-regulation between ±15V outputs without post-regulation LDOs, minimizing component count and board space. |
Use Scenario: Powering 4–20mA loop-powered sensors requiring precise 12V excitation from noisy 24V plant bus. IC Role / Device Role / Timing Role: Buck regulator with tight line regulation (0.03%/V) and low 6mA quiescent current. Use Value: Maintains sensor accuracy across 18–36V input variation while consuming <15mW idle power-critical for loop-powered operation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1071CT#PBF | Same silicon, but Commercial grade (0°C to 100°C junction temp) and TO-220 package with θJA = 75°C/W. | Limited to ambient ≤75°C; unsuitable for sealed enclosures or high-temp industrial environments. | Select LT1071IT#PBF when operating above 75°C ambient or requiring guaranteed performance over –40°C to 125°C. |
| LT1371CS8#TRPBF | 500kHz switching frequency, 3A switch, SO-8 package; lower RDS(on) (0.15Ω), higher IQ (2.5mA). | Enables smaller magnetics and capacitors but requires careful layout due to high-frequency EMI and lacks flyback regulation mode. | Choose LT1371CS8#TRPBF for compact, high-density designs where isolation is achieved via separate controller or digital regulation-not for optocoupler-free flyback. |
Compared with LT1071CT#PBF, the LT1071IT#PBF offers extended temperature reliability and lower thermal resistance in demanding environments; versus LT1371CS8#TRPBF, it trades higher frequency for proven flyback isolation capability and rugged 40kHz operation in noisy industrial settings.
Availability
LT1071IT#PBF is available at Aetrix Electronics and suitable for off-line AC/DC converters, battery-powered upconverters, and isolated dual-rail supplies requiring stable component supply and long-term industrial lifecycle support.
Supply support for LT1071IT#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 full product support, datasheets, and application notes for legacy Linear regulators.
The LT1071IT#PBF belongs to Linear's high-voltage monolithic switching regulator family, designed specifically for rugged, low-component-count DC/DC conversion in industrial, telecom, and automotive power systems where reliability and topology flexibility are critical.
FAQ
What is the maximum output power achievable with LT1071IT#PBF in buck configuration?
The LT1071IT#PBF delivers up to 50W in buck mode-calculated as 2.5A × 20V output-when thermally managed with adequate heatsinking. At 12V output, this supports 4.2A continuous load. Derating applies above 85°C case temperature per the 125°C max junction rating and θJA = 75°C/W specification. Real-world designs typically achieve 40–45W with 2°C/W heatsink.
Does LT1071IT#PBF support synchronization to an external clock?
No-LT1071IT#PBF does not support external clock synchronization. The datasheet states "Can be Externally Synchronized (Consult Factory)" only for custom versions; the standard LT1071IT#PBF uses a fixed 40kHz internal oscillator with ±5kHz tolerance. For synchronized operation, consider LT3748 or LT8304 flyback controllers with sync pins.
How is flyback regulation mode enabled on LT1071IT#PBF?
Flyback regulation mode is enabled by pulling the FB pin below 0.45V (typical) using an external resistor divider from VSW or transformer auxiliary winding. This disconnects the main error amplifier and connects the dedicated flyback amplifier to the comparator, allowing regulation of the reflected flyback pulse amplitude instead of output voltage directly-enabling fully isolated outputs without optocouplers.
What is the purpose of the VC pin on LT1071IT#PBF?
The VC pin on LT1071IT#PBF serves four functions: (1) error amplifier output for loop compensation, (2) current limit adjustment via external clamp voltage, (3) soft-start initiation using a capacitor to ramp VC voltage, and (4) shutdown activation when pulled below 0.15V, reducing supply current to 50µA. Its voltage ranges from 0.9V (light load) to 2.0V (full load) during normal operation.
Can LT1071IT#PBF replace LT1070IT#PBF in existing designs?
LT1071IT#PBF can replace LT1070IT#PBF only if the design operates within 2.5A switch current and accounts for higher RDS(on) (0.3Ω vs. 0.15Ω). Output power must be halved (e.g., 100W → 50W), and thermal design revised. Pinout and control logic are identical, but flyback reference voltage differs (16.3V vs. 1.24V), requiring FB network reconfiguration in flyback mode.
LT1071IT#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- TO-220-5
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up, Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost, Cuk, Flyback, Forward Converter
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 60V
- Voltage - Output (Min/Fixed):
- 1.25V
- Voltage - Output (Max):
- 65V (Switch)
- Current - Output:
- 2.5A (Switch)
- Frequency - Switching:
- 40kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-5
LT1071IT#PBF FAQ
1.How can I place an order for LT1071IT#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1071IT#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 LT1071IT#PBF reliable?
The price and inventory of LT1071IT#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1071IT#PBF is usually 5 days.
3.What payment methods are accepted for LT1071IT#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1071IT#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1071IT#PBF?
LT1071IT#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1071IT#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 LT1071IT#PBF?
For technical support, including LT1071IT#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1071IT#PBF requirements.
6.How does Aetrix verify that LT1071IT#PBF is sourced from the original manufacturer or authorized distributors?
All LT1071IT#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 LT1071IT#PBF meets industry standards.
7.What is the process for return or replacement of LT1071IT#PBF?
All LT1071IT#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1071IT#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 LT1071IT#PBF part is unused and in its original packaging.
Return procedure for LT1071IT#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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