Datasheet
SLVS009F − JUNE 1976 − REVISED FEBRUARY 2005
6
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
DESIGN EQUATIONS
I
(PK)
+ 2I
O
max
L(mH) +
V
I
–V
O
I
(PK)
t
on
(ms)
C
T
(pF) [ 12 t
on
(ms)
R1 + (V
O
–1.2V)kW
Choose L (50 to 500 µH), calculate
t
on
(10 to 150 µs)
R
CL
+
0.5 V
I
(PK)
C
O
(mF) [ t
on
(ms)
ƪ
V
I
* V
O
V
O
I
(PK)
) I
O
ƫ
V
ripple
(PK)
V
I
R
CL
8101314
TL497A
12
3
4567
R2 = 1.2 kΩ
R1
C
O
V
O
V
I
R
CL
14 13 10
8
123 4567
TL497A
L
R1
R2 = 1.2 kΩ
EXTENDED POWER CONFIGURATION
(using external transistor)
L
V
O
C
O
C
T
C
T
BASIC CONFIGURATION
(Peak Switching Current = I
(PK)
< 500 mA)
Figure 2. Positive Regulator, Step-Down Configurations