Cirrus Logic AN349 - Manual (Page 11)

AN349
AN349REV1 11
In almost all fluorescent ballast applications, there are no requirements for light-load efficiency. The most common topology used
for supplying V
cc
is shown in Figure 14. When migrating to the CS1601, no changes are necessary except that diode Z1 should
be a 13V to 15V zener diode. Capacitor C1 is the V
cc
capacitor and should be a 4.7
F, 25V ceramic capacitor. At the generation
of the aux supply, there can be a larger storage capacitor as well.
Figure 14. Typical Inexpensive Aux Supply
It is important to note that there are no changes needed in the second stage to make it compatible with the CS1601. However, if
the second stage is used to provide auxiliary supply to the entire ballast, care must be taken to meet the specifications of the
CS1601 as described in Table 2.
R1
R2
R3
D1
Z1 Aux C1
V rect