Analog Devices Inc. LT1795ISW#PBF

Overview

LT1795ISW#PBF from Analog Devices (formerly Linear Technology) is a dual current feedback amplifier optimized for high-current line driving in xDSL systems, delivering 500mA output drive per channel, 50MHz bandwidth at AV = 2 with 25Ω load, and 900V/µs slew rate. It operates from ±5V to ±15V supplies, features thermal shutdown and short-circuit protection, and is used in ADSL/HDSL2 central office line drivers.

For engineers reviewing the LT1795ISW#PBF datasheet, LT1795ISW#PBF pinout, LT1795ISW#PBF application, or LT1795ISW#PBF equivalent, this page provides verified specifications, TSSOP-20 pin mapping, real-world use cases in DSL infrastructure, and validated alternative options for line driver design.

Technical Context

The LT1795ISW#PBF employs a current feedback architecture enabling high slew rate and wide bandwidth while maintaining stability with large capacitive loads up to 10,000pF. Its dual-channel layout supports differential signaling in line driver configurations without crosstalk degradation - channel separation exceeds 80dB at ±10V output swing into 25Ω.

Shutdown control is implemented via SHDN and SHDNREF pins, allowing either full disablement (<200µA per amplifier) or adjustable quiescent current (15–42mA per amplifier) using external resistors. The COMP pin enables optional internal compensation for capacitive loads, reducing peaking but trading off bandwidth on resistive loads.

Key Specifications

Pinout & Package

LT1795ISW#PBF is housed in a thermally enhanced 20-lead TSSOP package (4.4mm width) with exposed pad internally connected to V– for improved heat dissipation. PCB layout requires direct copper connection to V– pins (4–7, 14–17) and the exposed pad.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual high-current line driver applications.

Compared with LT1207CFE#PBF and LT1497CS8#PBF, the LT1795ISW#PBF delivers 2× higher output current and integrated thermal shutdown, making it the sole option among the three qualified for full-rate ADSL central office deployment with 25Ω termination and 10,000pF load tolerance.

Availability

LT1795ISW#PBF is available at Aetrix Electronics and suitable for ADSL line driver modules, automated test equipment output stages, and broadband video distribution systems requiring stable component supply across extended temperature ranges (–40°C to 85°C).

Supply support for LT1795ISW#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, documentation, and manufacturing continuity for legacy Linear parts including the LT1795 series.

The LT1795ISW#PBF belongs to Linear's high-speed current feedback amplifier product line, designed specifically for broadband line driving in telecommunications infrastructure where high output current, low distortion, and robust thermal behavior are mandatory.

FAQ

What is the maximum capacitive load the LT1795ISW#PBF can drive stably?

The LT1795ISW#PBF is specified to remain stable with up to 10,000pF of capacitive load when the COMP pin is properly configured. This capability is critical for driving long PCB traces, transformer-coupled interfaces, or multiple parallel termination points in DSL line cards without oscillation or peaking. Stability is maintained across the full –40°C to 85°C operating range, and the device does not require external compensation networks for this load level.

Does the LT1795ISW#PBF support true dual-channel differential operation?

Yes, the LT1795ISW#PBF supports fully independent dual-channel operation with >80dB channel separation at ±10V output swing into 25Ω. Each channel has dedicated +IN, –IN, OUT, COMP, SHDN, and SHDNREF pins, enabling true differential line driving (e.g., one channel as inverting, one as noninverting) without crosstalk-induced distortion. The TSSOP-20 layout physically isolates input and output paths to minimize coupling.

How does the shutdown feature affect output impedance in the LT1795ISW#PBF?

When the LT1795ISW#PBF is placed in full shutdown (VSHDN = VSHDNREF), output impedance rises to >10MΩ, effectively disconnecting the amplifier from the load. However, the "partial shutdown" configuration - achieved by biasing SHDN and SHDNREF to intermediate voltages - maintains low output impedance (~50Ω) while reducing quiescent current, preserving line termination integrity during low-activity periods in DSL systems.

Can the LT1795ISW#PBF operate from a single +12V supply?

No, the LT1795ISW#PBF requires dual symmetric supplies (±5V to ±15V) and is not rated for single-supply operation. Its input common-mode range and output swing are referenced to ground and require both positive and negative rails to achieve ±12.5V output swing into 25Ω. Attempting single-supply use will result in clipping, instability, or permanent damage due to violation of absolute maximum ratings.

What is the thermal resistance (θJA) of the LT1795ISW#PBF in its TSSOP-20 package?

The LT1795ISW#PBF has a typical θJA of 40°C/W when mounted on a 2 × 2 inch double-sided 2 oz copper PCB with the exposed V– pad soldered to ground. This value assumes optimal thermal vias and copper area; θJA increases significantly with reduced copper area or absence of thermal pad connection. Junction temperature must be calculated as TJ = (PD × θJA) + TA to ensure operation remains below 150°C under worst-case load conditions.