Figure 22: External Clock Synchronization.
U3842T - UC3843T - UC3844T - UC3845T
EXTERNAL
SYNC INPUT 0.01µF
VREF
8
RT
4
CT
2
47Ω
1
R
R
+
+
-
EA
BIAS
OSC
2R
R
5
The diode clamp is required if the Sync amplitude is large enough to cause
the bottom side of CT to go more than 300mV below ground
D95IN352
Figure 23: External Duty Cycle Clamp and Multi Unit Synchronization.
VREF
RA
8
4
RB
5K
6
+
3
5
R
-
5K
Q
7
+
2
S
-
C
5K
1
NE555
1.44
f=
(RA + 2RB)C
Dmax =
RB
RA + 2RB
8
R
BIAS
R
4
OSC
+
+
2
-
EA
1
2R
R
5
TO ADDITIONAL
UC384XT
D99IN1060
11/15