MC54F161A View Datasheet(PDF) - Motorola => Freescale
Part Name
Description
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MC54F161A Datasheet PDF : 4 Pages
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MC74F161A • MC74F163A
LOGIC DIAGRAM
P0
PE
MC74F161A
MC74F163A
P1
P2
CEP
CET
MC74F163A
ONLY
P3
TC
CP
MR (MC74F161A)
CP
MC74F161A
ONLY
Q0
CP
D CP D
CD Q Q
Q0
DETAIL A
DETAIL A
DETAIL A
DETAIL A
SR (MC74F163A)
Q0
Q1
Q2
Q3
NOTE:
This diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
FUNCTIONAL DESCRIPTION
The MC74F161A and MC74F163A count in modulo-16
binary sequence. From state 15 (HHHH) they increment to
state 0 (LLLL). The clock inputs of all flip-flops are driven in
parallel through a clock buffer. Thus all changes of the Q out-
puts (except due to Master Reset of the MC74F161A) occur
as a result of, and synchronous with, the LOW-to-HIGH transi-
tion of the CP input signal. The circuits have four fundamental
modes of operation, in order of precedence: asynchronous re-
set (MC74F161A), synchronous reset (MC74F163A), parallel
load, count-up and hold. Five control inputs Master Reset
(MR, MC74F161A), Synchronous Reset (SR, MC74F163A),
Parallel Enable (PE), Count Enable Parallel (CEP) and Count
Enable Trickle (CET) — determine the mode of operation, as
shown in the Function Table. A LOW signal on MR overrides
all other inputs and asynchronously forces all outputs LOW. A
LOW signal on SR overrides counting and parallel loading
and allows all outputs to go LOW on the next rising edge of
CP. A LOW signal on PE overrides counting and allows infor-
mation on the Parallel Data (Pn) inputs to be loaded into the
flip-flops on the next rising edge of CP. With PE and MR
(MC74F161A) or SR (MC74F163A) HIGH, CEP and CET per-
mit counting when both are HIGH. Conversely, a LOW signal
on either CEP or CET inhibits counting.
The MC74F161A and MC74F163A use D-type edge-trig-
gered flip-flops and changing the SR, PE, CEP, and CET in-
puts when the CP is in either state does not cause errors, pro-
vided that the recommended setup and hold times, with
respect to the rising edge of CP, are observed.
FAST AND LS TTL DATA
4-76
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