MS-532| Application Note

GTLP Description and Technology Characteristics

February 1998 Revised December 2000

GTLP Description and Technology Characteristics
Gunning Transceiver Logic Plus (GTLP) is a Fairchild Semiconductor derivative of the JEDEC standard for GTL (JESD8-3). GTLP is a single-ended, open drain I/O technology that is optimized for driving distributed load backplane environments at high speeds. GTLP's I/O characteristics and output control circuitry make it possible for GTLP to operate parallel backplanes in the multi-gigabit range with loads over 30 cards. Figure 1 shows a simplified schematic of the typical LVTTL I/O and GTLP I/O. Fairchild GTLP transceivers translate TTL/LVTTL signals to GTLP levels for the backplane environment (Figure 2). GTLP offers 1V reduced output swing for low power consumption, low noise, and low EMI as well as an increased noise margin for greater design flexibility. GTLP has a tight 50mV switching threshold with high drive (30mA, 50mA and 100mA) that makes it possible for all the receivers to recognize a valid state on the incident wave rather than having to wait for the reflected wave. GTLP's open drain output allows
the designer to adjust the pull up termination in the system for better impedance matching and thereby optimize the performance of the backplane. GTLP devices are also hot insertion capable allowing minimal system downtime. GTLP devices range from 1 to 36 bits wide with packaging options that include US8, SSOP, TSSOP, and BGA.

GTLP Performance Compared to Other Technologies A Port (TTL/LVTTL) B Port (GTLP)

FIGURE 1.

2000 Fairchild Semiconductor Corporation

MS500122

www.fairchildsemi.com