Analog Devices Inc. LT1082IN8#PBF

Overview

LT1082IN8#PBF from Analog Devices (formerly Linear Technology) is a monolithic high-voltage current-mode switching regulator IC with an integrated 1A NPN power switch, operating from 3V to 75V input and supporting up to 100V switch voltage. It delivers up to 20W output power in buck/boost/flyback configurations, features 60kHz fixed-frequency operation, 4.5mA quiescent current, and isolated flyback regulation mode-enabling telecom 5V/0.7A supply generation from –48V input.

For engineers reviewing the LT1082IN8#PBF datasheet, LT1082IN8#PBF pinout, LT1082IN8#PBF application, or LT1082IN8#PBF equivalent, key selection considerations include its 100V switch breakdown rating, internal current-limit protection, shutdown mode (120µA), thermal derating in plastic DIP, and compatibility with LT1072-based designs requiring higher input voltage range.

Technical Context

The LT1082IN8#PBF implements current-mode control: switch duty cycle is directly set by sensed switch current rather than output voltage feedback, enabling fast line transient response and inherent pulse-by-pulse overcurrent protection. Its oscillator runs at 60kHz (typical), shifting to 12kHz under high FB pin sink current (≥350µA) for short-circuit protection in high-input-voltage applications like telecom supplies.

It integrates a 2.3V low-dropout internal regulator for biasing, a 1.244V bandgap reference (±20mV over temperature), error amplifier with 4400µmho transconductance, and dual-mode operation-normal regulation via FB pin voltage and isolated flyback regulation via programmable FB current (60–200µA) with 18.6V typical flyback reference. The VC pin serves as error amplifier output, current limit adjust, soft-start node, and shutdown control.

Key Specifications

Pinout & Package

N8 package: 8-lead plastic DIP (0.300" width), rated for industrial temperature range (–40°C to +125°C), θ_JA = 90°C/W. Includes two emitter pins (E1, E2) for ground path separation and optional current limit reduction.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage switching regulator applications.

Compared with LT1082CN8#PBF, the LT1082IN8#PBF extends operational reliability to industrial temperatures and cold starts; compared with LT1072HVCT#PBF, it adds 25V switch headroom and 20kHz higher frequency-enabling smaller magnetics and broader input coverage in single-supply designs.

Availability

LT1082IN8#PBF is available at Aetrix Electronics and suitable for telecom power supplies, industrial DC-DC converters, and high-voltage boost applications requiring stable component supply and long-term manufacturability.

Supply support for LT1082IN8#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 support, datasheet archives, and application engineering resources for legacy Linear products.

The LT1082IN8#PBF belongs to Linear's high-voltage monolithic switching regulator product line, designed specifically for ruggedized offline and telecom power conversion where integration, HV tolerance, and isolation simplicity are critical.

FAQ

What is the maximum input voltage supported by the LT1082IN8#PBF?

The LT1082IN8#PBF supports a maximum continuous input voltage of 75V. This rating is absolute and applies across its full industrial temperature range (–40°C to +125°C). Exceeding 75V risks permanent damage to the internal LDO and oscillator circuitry, even if the switch itself is rated for 100V. Designers must ensure transient clamping or input filtering limits VIN to ≤75V under all operating and fault conditions.

Can the LT1082IN8#PBF be used in flyback topology without an optocoupler?

Yes, the LT1082IN8#PBF supports optocoupler-free isolated flyback regulation via its dedicated flyback mode. When the FB pin sinks 60–200µA (e.g., through a resistor from auxiliary winding), the IC switches to regulating the amplitude of the reflected flyback pulse instead of the primary output voltage. This eliminates the optocoupler while maintaining ±3% output regulation across line and load-confirmed in AN19 and Figure 1082 TA03.

How does the dual-emitter configuration (E1/E2) affect performance in the LT1082IN8#PBF?

In the LT1082IN8#PBF's N8 package, connecting both E1 and E2 to ground enables full 1A switch current and lowest R_SW (1.2Ω max). Leaving E2 open reduces switch current limit by ~2× but doubles R_SW, increasing conduction loss above 100mA. This trade-off is useful for limiting fault current without changing external components-but efficiency drops significantly at medium-to-high loads.

What triggers the 60kHz-to-12kHz frequency shift in the LT1082IN8#PBF?

The LT1082IN8#PBF shifts from 60kHz to 12kHz when the FB pin sinks ≥350µA while held near 0.6V-indicating hard short-circuit or extreme overload. This feature prevents switch saturation and thermal runaway in high-input-voltage scenarios (e.g., –48V telecom). The shift is automatic and requires no external circuitry; however, R_FB must be 1k–1.2kΩ to ensure proper triggering without false activation.

Is the LT1082IN8#PBF pin-compatible with the LT1072 series?

Yes, the LT1082IN8#PBF shares identical pinout and footprint with the LT1072HV family in N8, Q, and T packages. This allows drop-in replacement in existing LT1072 designs-provided input voltage does not exceed 60V (LT1072HV limit) and flyback reference differences (16V vs. 18.6V) are accommodated in feedback network design.