The I74F776A is an octal bidirectional latched transceiver and is intended to provide the electrical interface to a high performance wired–OR bus. The B port inverting drivers are low–capacitance open collector with controlled ramp and are designed to sink 100mA from 2 volts. The B port inverting receivers have a 100 mV threshold region and a 4ns glitch filter.
The I74F776A B port interfaces to ’Backplane Transceiver Logic’ (BTL).
BTL features a reduced (1V to 2V) voltage swing for lower power consumption and a series diode on the drivers to reduce capacitive loading. Incident wave switching is employed, therefore BTL propagation delays are short. Although the voltage swing is less for BTL, so is its receiver threshold, therefore noise margins are excellent. BTL offers low power consumption, low ground bounce, EMI and crosstalk, low capacitive loading, superior noise margin and low propagation delays. This results in a high bandwidth, reliable backplane.
The I74F776A A port has TTL 3–state drivers and TTL receivers with a latch function. A separate high–level control voltage input (VX) is provided to limit the A side output level to a given voltage level (such as 3.3V). For 5.0V systems, VX is simply tied to VCC. The I74F776A has a designed feature to control the B output transitions during power sequencing. There are two possible sequencing, They are as follows: 1.When LE = low and OEBn = low then the B outputs are disabled untilthe LE circuitry takes control. Then the B outputs will follow the A inputs, making a maximum of one transition during power–up (or down). 2. If LE = high or OEBn = high then the B outputs will be disabled during power–up (or down).
Octal latched transceiver
Drives heavily loaded backplanes with equivalent load impedances down to 10 ohms
High drive (100mA) open collector drivers on B port
Reduced voltage swing (1 volt) produces less noise and reduces power consumption
High speed operation enhances performance of backplane buses and facilitates incident wave switching
Compatible with Pi–bus and IEEE 896 Futurebus standards
Built–in precision band–gap reference provides accurate receiver thresholds and improved noise immunity
Controlled output ramp and multiple GND pins minimize ground bounce
Glitch–free power up/power down operation
Multiple package options
Industrial temperature range available (–40°C to +85°C)
PLCC 28 package. Manufactured by Signetics.