MB3773 Datasheet, PDF (23/29 Pages) Fujitsu Component Limited. – Power Supply Monitor with Watch-Dog Timer

MB3773
Description of Application Circuits
Using one MB3773, this application circuit monitors multiple microprocessor in one system. Signals from each
microprocessor are sent to FF1, FF2 and FF3 clock inputs. Figure 2 shows these timings. Each flip-flop operates
using signals sent from microprocessor as its clock pulse. When even one signal stops, the relevant receiving
flip-flop stops operating. As a result, cyclical pulses are not generated at output Q3. Since the clock pulse stops
arriving at the CK terminal of the MB3773, the MB3773 generates a reset signal.
Note that output Q3 frequency f will be in the following range, where the clock frequencies of CK1, CK2 and CK3
are f1, f2 and f3 respectively.
f-1--0^{- ≤ 1-f- ≤} f-1--1^{- + -f1--}2^{- + -f1--}3^-
where f0 is the lowest frequency among f1, f2 and f3.
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