Migrating from the Teridian 73

For STBs and DTVs that currently use the Teridian 73S8024RN low-cost smart-card interface or any other 8024-like device for a conditional access or a payment interface slot, the Teridian 73S8009R smart-card interface is an attractive alternative. The 73S8009R offers technical advantages and eventually a lower cost. The 73S8009R is a “transparent” smart card interface: the IC provides an image of each smart-card signal through dedicated digital I/Os to the host processor. This contrasts with the 73S8024RN which adds card clock dividing circuits, card activation sequencing, and a crystal oscillator circuit. While the 73S8009R has more design flexibility, certain hardware and firmware changes may be necessary to accommodate 8024 designs for the more simplistic 73S8009R IC. This application note explains how to migrate from the Teridian 73S8024RN to the 73S8009R. It assumes that the host processor is typically an A/V decoder processor that already handles the smart-card protocol layer to communicate with smart cards.