RPT-81

The RPT-81 has the following features including On-Chip ALBO Diode;On-Chip Voltage Regulator (RPT-81);Low Power Operation (100mW);Pin-Compatible with XR-C277.

The PMI PCM Repeater Circuits are monolithic integrated circuits which perform all the active functions required for a regenerative repeater operating at 1.544-2.048 Mega-bits per second (Mbps) data rates on PCM lines.In a PCM carrier system, coded information is transmitted over paired cables by the presence or absence of pulses in specified time slots. The RPT-81 regenerate all pulses that meet threshold requirements without inserting pulses incorrectly during empty time slots.Additional system functions have been incorporated on-chip. These include an Automatic Line Build Out (ALSO) circuit that compensates for up to 36dB of line loss and an oscillator control pin that permits injectioned-locked (free-running) or pulsed-tank operation. Biopoiar pulse transmission, the transmission of alternately positive and negative pulses, is used on repeatered lines to remove the DC component from the unipolar PCM pulse train. This also places the principle energy components in the 0-1.544MHz band, as opposed to the 0-3.088MHz band for the unipolar pulse train. The absence of a DC component in the bipolar pulse train permits the repeaterto be transformer coupled to the line and helps to prevent time shifting of the regenerator firing level with variation in input pulse density.

The logic threshold detector produces an output on the T+ line for a positive pulse and an output on the T- line for a negative pulse. The T+ line enables the NAND gate of FF+and the T- line enables the NAND gate of FF-. A T+ output pulse from the logic threshold detector is ANDed with the strobe pulse to set the FF+ flip flop which turns on its corresponding  output transistor, causing current to flow through one half of the output transformer primary. A positive output pulse results. Similarly, A T-output pulse and astrobe pulse are AN Ded to set the FF-flip flop, thus causing a negative output pulse. Theflipflops are turned off (and the output pulse terminated 1 bythe regenerated clock pulse. In this way the output pulse is controlled by the oscillator tank circuit and not the incoming pulse.