AD8328ACP-REEL

Overview

The AD8328 is a 5 V upstream cable line driver designed for DOCSIS and EuroDOCSIS reverse path transmission. It features digitally programmable gain over a 59 dB range with 1 dB steps via an SPI interface. The device supports differential or single-ended inputs, maintaining a 300 Ω output impedance that matches 75 Ω loads through a 2:1 transformer. Key performance metrics include a -54 dBc SFDR at 65 MHz and an output noise level of 1.2 nV/√Hz at minimum gain. It operates from a single 5 V supply with sleep modes reducing current to 20 μA.

Feature Summary

• Digital gain control via SPI interface with 59 dB range
• Maintains 75 Ω output impedance in transmit enable and disable states
• Integrated sleep and power-down modes for low quiescent current
• Supports both differential and single-ended input configurations

Applications

• DOCSIS and EuroDOCSIS cable modems
• CATV set-top boxes
• CATV telephony modems
• Coaxial and twisted pair line drivers

Procurement Notes

Verify the specific package variant (LFCSP or QSOP) required for the design, as thermal characteristics differ between packages. Confirm that the component status is acceptable for new designs, noting that official documentation may classify this part as obsolete. Ensure the ordering suffix matches the desired temperature range and packaging format specified in the manufacturer's current guide.

Selection Notes

Select the AD8328 for applications requiring precise digital gain adjustment in upstream cable paths. The device is suitable where low distortion and high isolation are critical for signal integrity. Consider the available supply voltage constraints, as it requires a 5 V rail. Evaluate the need for external transformers for output matching and ensure the system can accommodate the serial interface timing requirements for gain programming.

Part Context

The AD8328 belongs to Analog Devices' family of upstream cable line drivers intended for broadband communication infrastructure. It addresses the needs of hybrid fiber-coaxial networks by providing linear amplification with digital control capabilities. This component serves as a key interface between baseband processing units and the coaxial network, ensuring compliant signal levels for head-end reception.

Replacement Considerations

Publicly confirmed substitutes include the AD8324, which offers similar functionality but operates on a 3.3 V supply. Designers transitioning to the AD8324 must account for differences in supply voltage, gain range, and output drive capabilities. Verify pin compatibility and adjust biasing networks accordingly when replacing the AD8328 with alternative drivers in existing layouts.