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SN54/74LS390
DUAL DECADE COUNTER; SN54/74LS393
DUAL 4-STAGE
BINARY COUNTER
DUAL DECADE COUNTER;
The SN54 / 74LS390 and SN54 / 74LS393 each contain a pair of high-speed
4-stage ripple counters. Each half of the LS390 is partitioned into a
DUAL 4-STAGE
divide-by-two section and a divide-by five section, with a separate clock input BINARY COUNTER
for each section. The two sections can be connected to count in the 8.4.2.1 LOW POWER SCHOTTKY
BCD code or they can count in a biquinary sequence to provide a square wave
(50% duty cycle) at the final output.
Each half of the LS393 operates as a Modulo-16 binary divider, with the last
three stages triggered in a ripple fashion. In both the LS390 and the LS393,
the flip-flops are triggered by a HIGH-to-LOW transition of their CP inputs.
Each half of each circuit type has a Master Reset input which responds to a J SUFFIX
HIGH signal by forcing all four outputs to the LOW state. CERAMIC
CASE 620-09