User`s guide

56 | P a g e
resets the flip-flop which in turn discharges the capacitor rapidly
and drives the output to its low state.
Output Rise Time tR - 100 - - 100 - ns
Output Fall Time tF - 100 - - 100 - ns
NOTES:
2. When the output is in a high state, the DC supply current is typically 1mA less than the low state value.
3. The threshold current will determine the sum of the values of R1 and R2 to be used in Figure 4 (astable operation); the maximum
total
R1 + R2 = 20M.
Electrical Specifications TA = 25oC, V+ = 5V to 15V Unless Otherwise Specified (Continued)
PARAMETER SYMBOL TEST CONDITIONS
CA555, LM555 CA555C, LM555C, NE555
MIN TYP MAX MIN TYP MAX UNITS
6
THRESHOLD
7
RESET
DISCHARGE
VRESET
DISCHARGE
3
OUTPUT
FLIP-FLOP OUTPUT
TRIGGER
COMPARATOR
THRESHOLD
COMPARATOR
4.7K 830 4.7K
D1 D2
Q3 Q4
Q7
Q2 Q5
Q1
10K
Q8
Q6
100
100K
Q9
Q11 Q12
1K
Q10
5K
Q13
Q16
7K
D3
Q14
Q15
Q17
3.9K
Q19
Q20
Q21
Q18
8
V+
CONTROL
VOLTAGE
5K 6.8K
5K
4.7K
220
4.7K
5
2
4
1
TRIGGER
D4
NOTE: Resistance values are in ohms.
CA555, CA555C, LM555, LM555C, NE555
8-6
Since the charge rate and threshold level of the comparator
are both directly proportional to V+, the timing interval is relatively