Datasheet
SLVS009F − JUNE 1976 − REVISED FEBRUARY 2005
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
V
I
L
14 13 10 8
7654321
TL497A
R2 = 1.2 kΩ
R1
V
O
C
O
BASIC CONFIGURATION
(Peak Switching Current = I
(PK)
< 500 mA)
V
I
R
CL
L
R1
8101314
12345
EXTENDED POWER CONFIGURATION
(using external transistor)
TL497A
DESIGN EQUATIONS
I
(PK)
+ 2I
O
max
ƪ
V
O
V
I
ƫ
L(mH) +
V
I
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
(25 to 150 µs)
R
CL
+
0.5 V
I
(PK)
C
O
(mF) [ t
on
(ms)
ƪ
V
I
V
O
I
(PK)
) I
O
ƫ
V
ripple
(PK)
C
T
R2 = 1.2 kΩ
V
O
C
O
C
T
R
CL
Figure 1. Positive Regulator, Step-Up Configurations