MM54HC149/MM74HC149
8 Line to 8 Line Priority Encoder
General Description
This priority encoder utilizes advanced silicon-gate CMOS
technology. It has the high noise immunity and low power
consumption typical of CMOS circuits, as well as the speeds
and output drive similar to LS-TTL.
This priority encoder accepts 8 input request lines, RI7±RI0,
and outputs 8 lines, RO7±RO0. Only one request output
can be low at a time. The output that is low is dependent on
the highest priority request that is low. The order of priority
is RI7 highest and RI0 lowest. Also provided is and enable
input, RQE, which when high forces all outputs high. A request
output is also provided, RQP, which goes low when
any RIn is active.
All inputs to this device are protected from damage due to
electrostatic discharge by diodes to VCC and ground.
Features
Y Propagation delay: 15 ns typical
Y Wide power supply range: 2±6V
Y Low quiescent current: 80 mA max (74HC Series)
Y Wide input noise immunity