DESCRIPTION — The ’90 is a 4-stage ripple counter containing a high speed
flip-flop acting as a divide-by-two and three flip-flops connected as a divideby-
five counter. It can be connected to operate with a conventional BCD output
pattern or it can be connected to provide a 50% duty cycle output. In the
BCD mode, HIGH signals on the Master Set (MS) inputs set the outputs to
BCD nine. HIGH signals on the Master Reset (MR) inputs force all outputs
LOW. For a similar counter with corner power pins, see the ’LS290; for dual
versions, see the ’LS390 and ’LS490.