CD4541 Datasheet, PDF (5/7 Pages) Unisonic Technologies – PROGRAMMABLE TIMER CMOS IC

UTC CD4541
CMOS IC
OPERATING CHARACTERISTICS
With Auto Reset pin set to a “0” the counter circuit is initialized by turning on power. Or with power already on,
the counter circuit is reset when the Master Reset pin is set to a “1”. Both types of reset will result in synchronously
resetting all counter stages independent of counter state.
The RC oscillator frequency is determined by the external RC network, i.e.:
f=
1
2.3 RtcCtc
if (1 kHzÙ f Ù 100kHz)


and RS ~ 2 Rtc where RSÚ10 kƸ
The time select inputs (A and B) provide a two-bit address to output any one of four counter stages (2⁸, 2¹⁰, 2¹³,
and 2¹⁶). The 2ⁿ counts as shown in the Division Ratio Table represent the Q output of the Nth stage of the counter.
When A is “1”, 2¹⁶ is selected for both states of B.
However, when B is “0”, normal counting is interrupted and the 9th counter stage receives its clock directly from
the oscillator (i.e., effectively outputting 2⁸).
The Q/Q select output control pin provides for a choice of output level. When the counter is in a reset condition
and Q/Q select pin is set to a “0” the Q output is a “0”. Correspondingly, when Q/Q select pin is set to a “1” the Q
output is a “1”.
When the mode control pin is set to a “1”, the selected count is continually transmitted to the output. But, with
mode pin “0” and after a reset condition the RS flip-flop resets (see Logic Diagram), counting commences and after
2^n-1 counts the RS flip-flop sets which causes the output to change state. Hence, after another 2^n-1 counts the output
will not change. Thus, a Master Reset pulse must be applied or a change in the mode pin level is required to reset
the single cycle operation.




RC Oscillator Frequency as a Function of RTC and C
RC Oscillator Frequency as a Function of RTC and C
1.0M
70
VDD =10V
VDD =10V
100k
7
10k
0.7
1.0k
0.0001
0.001
0.01
0.1
RESISTANCE ,RTC ( KȤ )
f as a function of C and (RTC =56 KȤ, Rs =120k )
0.07
1.0k
10k
100k
1.0M
CAPACITANCE, C(µF)
f as a function of RTC and (C=100pF, Rs=2RTC)
UTC UNISONIC TECHNOLOGIES CO., LTD.
5
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