Omron H3FA -, Datasheet, Page: 7 / 12

Solid-state Timer
H3FA
7
■
External Resistors and Operating Time (Reference Value)
Refer to the following characteristics diagrams
when using an external resistor.
• Use an external resistor rated at about
0.1 W/1 M
Ω
for H3FA-A, -SA, -AU, and -SAU
or 0.1 W/3 M
Ω
for H3FA-B, -SB, -BU, and -
SBU.
• Do not run leads parallel to power lines and
keep the leads shorter than 2 m to minimize
the effects of external noise.
• The characteristics diagrams represent
typical data. The factory set operating time
may not always be uniform from one product
to another. A variable resistor is
recommended if more precise time
adjustments are required. The operating time
is slightly longer than the set time as the
length of the lead increases.
■
Extending the Reset Time
DIP Timers have a shorter reset time than that of conventional timers
for use in solid-state circuit applications. To extend the reset time to
that of conventional timers, i.e., about 100 ms, during operation,
connect the Timer to a capacitor from the table as shown in the
following diagram. The reset time after the set time has elapsed will
vary with the load relay, so select an appropriate capacitor for the
load relay.
External resistor (M
Ω
)
120
100
80
60
40
20
0 0.5 1 1.5
Operating time (%)
H3FA-B/-SB/-BU/-SBU H3FA-A/-SA/-AU/-SAU
External resistor (M
Ω
)
120
100
80
60
40
20
0 1 2 3 4
Operating time (%)
Rated voltage Capacitor capacity
12 V DC 10
µ
F, 25 V
24 V DC 4.7
µ
F, 50 V
5 and 6 V DC 22
µ
F, 16 V
C
24 23 22 21
1 2 3 4