PRN112

Peripheral devices like disk drives, printers, and CD ROMs are connected to host through a special bus called SCSI (Small Computer System Interface). The fast edge rated signals that are transmitted through the SCSI cable generate ringing on the bus. This will slow down communication between host and peripherals. The SCSI standard recommends proper resistor (Thévenin) termination at host and peripheral locations to eliminate transmission line effects.

CAMDs PRN102/112 Dual Thévenin Termination Networks offer high integration and performance in a miniature QSOP or SOIC package, which saves critical board area and provides manufacturing cost and reliability efficiencies.

Why thin film resistor networks? A terminating resistor is used to reduce or eliminate unwanted reflections on a  transmission line. It can perform this function only when its resistance value matches the characteristic impedance of the transmission line. The resistors used for terminating the transmission lines should be noiseless, stable and functional at high frequencies. Unlike thin film-based resistor networks, conventional thick film resistors used for terminating transmission lines are not stable over temperature and time and impose system performance limitations at very high frequencies.