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Analog Devices Inc. LT1082IT#PBF
- Part No.:
- LT1082IT#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- TO-220-5
- Datasheet:
-
LT1082IT#PBF.pdf
- Description:
- IC REG BCK BST ADJ 850MA TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:104
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Product details
Overview
LT1082IT#PBF from Analog Devices (formerly Linear Technology) is a monolithic high-voltage current-mode switching regulator IC with an integrated 1A power switch, 100V switch breakdown voltage, 60kHz fixed-frequency operation, and 4.5mA quiescent current. It supports buck, boost, flyback, forward, and inverting topologies and delivers up to 20W output power without external switches - used in telecom negative-to-positive 5V/0.7A supplies from –48V input.
For engineers reviewing the LT1082IT#PBF datasheet, LT1082IT#PBF pinout, LT1082IT#PBF application, or LT1082IT#PBF equivalent, this page provides verified functional identity, thermal and electrical specifications across its –40°C to 125°C industrial operating range, package-specific pin mapping for TO-220 (T package), and confirmed alternative parts for high-voltage DC/DC design reuse.
Technical Context
The LT1082IT#PBF implements current-mode control: switch duty cycle is set by real-time switch current sensing rather than output voltage feedback alone, enabling fast line transient response and inherent pulse-by-pulse overcurrent protection. Its internal 1.24V bandgap reference feeds an error amplifier whose transconductance (gm = 3000–6000 µmho) sets current-limit threshold via the VC pin.
It features dual regulation modes: standard feedback mode (FB pin referenced to 1.24V) and isolated flyback mode (FB pin biased at 60–200µA to enable transformer-coupled floating outputs). A unique short-circuit protection shifts switching frequency from 60kHz to 12kHz when FB pin current exceeds 350µA - critical for telecom –70V input short-circuit survival.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 75V - enables direct operation from wide-range industrial or telecom supplies without pre-regulation. |
| Switch Breakdown Voltage | 100V - supports flyback designs with ≥70V reflected voltages and withstands surge transients in harsh environments. |
| Switch Current Limit | 1.07A typical (at 20% duty cycle, TJ = 25°C) - defines maximum continuous output power in buck/boost configurations. |
| Quiescent Current | 4.5mA - minimizes no-load power loss in battery-backed or always-on systems. |
| Shutdown Supply Current | 120µA - allows ultra-low-power standby in energy-sensitive applications like remote sensors. |
| Reference Voltage | 1.244V ±20mV - precision feedback reference enabling ±1% output voltage regulation with proper resistor tolerance. |
| Operating Junction Temp | –40°C to 125°C - validated for industrial ambient conditions; θJA = 75°C/W (IT package) enables convection-cooled designs. |
Pinout & Package
LT1082IT#PBF is housed in a 5-lead plastic TO-220 (T) package with exposed tab for thermal dissipation. Pin 1 = VIN, Pin 2 = VSW, Pin 3 = GND, Pin 4 = FB, Pin 5 = VC. The emitter is internally tied to GND; no separate E1/E2 pins as in N8 package.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main power input | Accepts 3–75V supply; powers internal LDO (2.3V) and oscillator; must be bypassed with ≥10µF low-ESR capacitor. |
| VSW | Switch collector output | Drives external inductor/diode; rated for 100V breakdown; connects to primary winding in flyback or boost topologies. |
| GND | Power and signal reference | Common return for internal circuitry, switch emitter, and feedback network; requires low-impedance PCB plane. |
| FB | Feedback input / mode select | At 1.244V → normal regulation; at 60–200µA sink → isolated flyback mode; clamped at 0.12–0.36V (low) and 1.8–2.3V (high). |
| VC | Error amplifier output / control interface | 0.9–2.0V during regulation; externally clamped to adjust current limit; pulled <0.15V for shutdown (120µA IQ). |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode switching architecture | Enables immediate line transient response and eliminates need for complex loop compensation across wide VIN/VOUT ranges. |
| Isolated flyback regulation mode | Generates fully floating outputs without optocouplers or auxiliary windings - reduces BOM count and improves reliability. |
| High-voltage short-circuit protection | Frequency shift-down to 12kHz under FB overload prevents switch saturation failure in –70V telecom short-circuit events. |
| Externally synchronizable (75–90kHz) | Allows noise-sensitive systems to avoid EMI bands by overriding internal 60kHz oscillator with external clock signal. |
| Adjustable current limit via VC pin | Linear scaling from 0A (VC ≈ 1V) to 1.6A (VC ≈ 2V) enables precise overcurrent threshold tuning without component changes. |
Applications
| Negative-to-Positive Telecom Supply | Isolated Dual-Rail Power |
|---|---|
Use Scenario: Generating +5V/0.7A from –48V telecom battery bus in central office equipment. IC Role / Device Role / Timing Role: Primary controller in flyback topology; regulates output using secondary-side rectified voltage sensed via auxiliary winding. Use Value: Eliminates optocoupler and TL431, reducing component count by 3 and improving long-term stability under temperature cycling. |
Use Scenario: Providing isolated ±15V/0.3A rails for op-amp signal conditioning in industrial PLC analog I/O modules. IC Role / Device Role / Timing Role: Flyback controller regulating both positive and negative outputs simultaneously via single transformer with center-tapped secondary. Use Value: Achieves ≤±3% cross-regulation without post-regulators, cutting board space and cost vs. dual independent converters. |
| High-Voltage Boost Converter | Industrial Input Range DC/DC |
Use Scenario: Stepping 15V input to 90V/120mA for vacuum tube biasing or sensor excitation in test equipment. IC Role / Device Role / Timing Role: Boost controller with internal 1A switch; operates at fixed 60kHz with external diode and inductor. Use Value: Delivers full 90V output with >75% efficiency at 120mA load - avoids need for external MOSFET driver or gate transformer. |
Use Scenario: Converting 12–48V vehicle or factory bus to stable 5V/1A for embedded microcontrollers and CAN transceivers. IC Role / Device Role / Timing Role: Buck controller supporting wide input range; uses current-mode control to maintain regulation during engine cranking dips. Use Value: Maintains regulation down to 3V input (with 100% duty cycle) - survives cold-crank events where 12V bus drops below 6V. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1072HV | Lower max switch voltage (75V vs. 100V); higher switch current limit (1.25A vs. 1.07A); 40kHz frequency; same pinout. | Not suitable for >75V reflected voltages or –70V telecom inputs; better for medium-voltage boost/flyback with higher current demand. | Select LT1072HV only if input voltage stays ≤60V and higher peak switch current is required - verify flyback clamp margin. |
| LM5009AMM/NOPB | Higher frequency (1MHz vs. 60kHz); lower IQ (1.5mA vs. 4.5mA); 80V switch rating; requires external MOSFET. | Enables smaller magnetics but lacks integrated switch - adds complexity and layout sensitivity in high-noise environments. | Choose LM5009AMM/NOPB for size-constrained designs needing >500kHz operation; retain LT1082IT#PBF for simplicity and ruggedness in telecom/industrial settings. |
Compared with LT1072HV and LM5009AMM/NOPB, the LT1082IT#PBF uniquely combines 100V switch rating, integrated 1A switch, and flyback isolation mode - making it irreplaceable for compact, optocoupler-free –48V telecom supplies and high-reliability industrial flyback converters.
Availability
LT1082IT#PBF is available at Aetrix Electronics and suitable for telecom power supplies, isolated industrial DC/DC converters, high-voltage boost circuits, and ruggedized embedded power systems requiring stable component supply across extended temperature and voltage ranges.
Supply support for LT1082IT#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 technical and manufacturing continuity for legacy Linear power products including the LT1082 series.
The LT1082 product line was designed specifically for high-voltage, wide-input industrial and telecom DC/DC conversion - emphasizing integration, fault resilience, and simplified isolated design without optocouplers.
FAQ
What is the maximum allowable input voltage for LT1082IT#PBF?
The absolute maximum supply voltage for LT1082IT#PBF is 75V, and it operates continuously across 3V to 75V. Exceeding 75V risks permanent damage to the internal switch. The 100V switch breakdown voltage is a safe margin for transient spikes and reflected voltages in flyback topologies - not a continuous operating rating. Always include input overvoltage clamping for systems with potential surges.
Does LT1082IT#PBF support isolated flyback regulation without an optocoupler?
Yes, LT1082IT#PBF supports isolated flyback regulation without an optocoupler via its dedicated flyback mode: when the FB pin sinks 60–200µA, the IC regulates the amplitude of the reflected flyback pulse instead of the primary-side feedback voltage. This enables fully floating outputs with tight cross-regulation - confirmed in LT1082 datasheet Figure 1082 TA03 and Application Note AN19.
What is the thermal resistance (θJA) of the LT1082IT#PBF package?
The LT1082IT#PBF (TO-220, T package) has a junction-to-ambient thermal resistance (θJA) of 75°C/W under standard JEDEC 2S2P board conditions. Its junction-to-case (θJC) is 8°C/W. These values assume the exposed tab is soldered to a ≥1 in² copper pour - derate θJA by ~20% if using minimal copper or no heatsink. Maximum junction temperature remains 125°C.
Can LT1082IT#PBF be synchronized to an external clock?
Yes, LT1082IT#PBF can be externally synchronized between 75kHz and 90kHz by pulling the VC pin to ground with a transistor for <1µs pulses. This overrides the internal 60kHz oscillator while preserving regulation accuracy. Synchronization is confirmed in datasheet Section "LT1082 Synchronizing" (page 9) and requires careful pulse width control to avoid offset voltage shifts.
How does the LT1082IT#PBF implement short-circuit protection?
LT1082IT#PBF implements high-voltage short-circuit protection by shifting switching frequency from 60kHz to 12kHz when FB pin current exceeds 350µA - a condition occurring during output shorts in negative-input telecom supplies. This prevents switch saturation and thermal runaway. The feature is explicitly documented in the "Features" section and Figure 1082 G03 (Short-Circuit Frequency Shift-Down vs Feedback Current).
LT1082IT#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
- Output Configuration:
- Positive or Negative, Isolation Capable
- Topology:
- Buck, Boost, Flyback, Forward Converter
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 75V
- Voltage - Output (Min/Fixed):
- 1.244V
- Voltage - Output (Max):
- 100V (Switch)
- Current - Output:
- 850mA (Switch)
- Frequency - Switching:
- 12kHz ~ 60kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-5
LT1082IT#PBF FAQ
1.How can I place an order for LT1082IT#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1082IT#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 LT1082IT#PBF reliable?
The price and inventory of LT1082IT#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1082IT#PBF is usually 5 days.
3.What payment methods are accepted for LT1082IT#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1082IT#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1082IT#PBF?
LT1082IT#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1082IT#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 LT1082IT#PBF?
For technical support, including LT1082IT#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1082IT#PBF requirements.
6.How does Aetrix verify that LT1082IT#PBF is sourced from the original manufacturer or authorized distributors?
All LT1082IT#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 LT1082IT#PBF meets industry standards.
7.What is the process for return or replacement of LT1082IT#PBF?
All LT1082IT#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1082IT#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 LT1082IT#PBF part is unused and in its original packaging.
Return procedure for LT1082IT#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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