The T213 counter is internally connected by a four-stage JK flip-flop into a four-bit asynchronous counter . The outer lead arrangement and function of the T213 counter are as shown in the figure. The R01, R02, R03, and R04 terminals of the T213 counter are output with QA, QC, and QD. Connected to various feedback lines, you can get the N-ary counter according to the standard 8421 code.
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