SA5217D/01,118

Overview

The SA5217D/01,118 is a 75MHz postamplifier system designed to accept low-level high-speed signals and convert them into TTL level outputs. It features an auto-zeroed first stage with noise shaping, a symmetrical limiting second stage, and a matched rise/fall time TTL output buffer. The device operates on a single 5V supply, typically consuming 40mA. It includes user-configurable input threshold and hysteresis settings to maximize signal-to-noise ratio and ensure low Bit Error Rate (BER). An auto-zero loop replaces input coupling capacitors, and a signal absent flag indicates when signals fall below the threshold.

Feature Summary

• Features an auto-zero loop for DC offset cancellation, allowing direct connection to transimpedance amplifiers without coupling capacitors.
• Provides adjustable input threshold and hysteresis via external resistors to optimize signal-to-noise ratio.
• Includes a built-in LED driver that activates when the input signal exceeds the threshold level.
• Offers a low signal flag output that forces the TTL data output to the last logic state during signal absence.

Applications

• Fiber optics receivers
• Communication links in Industrial and/or Telecom environments with high EMI/RFI
• Local Area Networks (LAN)
• Synchronous Optical Networks (SONET) STS-1

Procurement Notes

Verify the specific ordering suffix '01,118' against the manufacturer's current documentation to confirm package type and temperature range specifications. Ensure compatibility with the intended operating voltage of 4.5V to 5.5V. Confirm that the 20-pin Small Outline Large (SOL) package dimensions align with the target PCB layout requirements before finalizing procurement.

Selection Notes

Select this component when interfacing with SA5210, SA5211, or SA5212A transimpedance amplifiers for fiber optic applications. It is suitable for systems requiring a wideband operation up to 75MHz and programmable threshold/hysteresis levels. Consider its differential input structure for excellent power supply rejection ratio and its ability to handle long strings of identical bits in the data stream.

Part Context

This part belongs to the SA521x family of optical receiver components, specifically serving as the postamplifier stage. It is designed to work in conjunction with preamplifiers like the SA5210/5211/5212A to convert photodetector currents into standard digital TTL levels. The device represents a 'system on a chip' solution for high-speed optical communication links.

Replacement Considerations

The SA5214 is noted as a related device; however, it differs by providing access to internal amplifier stages A1 and A2, whereas the SA5217 focuses on the A2 output and A8 input for Schmitt trigger activation.

FAQ

How does the SA5217 handle DC offset from the preceding transimpedance amplifier?

It utilizes an auto-zero loop connected to pins CAZP and CAZN, which cancels the DC offset from the transimpedance amplifier and the SA5217 itself, eliminating the need for input coupling capacitors.

What is the function of the FLAG pin?

The FLAG pin is a digital output that goes LOW when data is present above the threshold. When HIGH, it indicates a low signal condition, which can be used to jam the data output if connected to the JAM pin.

Can the threshold and hysteresis be adjusted?

Yes, the threshold voltage and hysteresis voltage range are user-configurable using external resistors connected to the THRESH and RHYST pins, respectively.