TL497A
SWITCHING VOLTAGE REGULATORS
SLVS009D – JUNE 1976 – REVISED JULY 1999
APPLICATION INFORMATION
RCL
VI
14
13
10
TL497A
8
R1
CO
L ( H)
1
2
3
CT
4
5
6
7
R2 = 1.2 kΩ
L
VO
DESIGN EQUATIONS
I
+
2 IO max
(PK)
m
V
O
V
I
+
I VI
(PK)
t on ( s)
m
Choose L (50 to 500
µH),
calculate
ton (25 to 150
µs)
BASIC CONFIGURATION
(Peak Switching Current = I(PK) < 500 mA)
RCL
VI
L
VO
C (pF)
T
[
12 ton (
m
s)
R1
+
(VO – 1.2 V) k
W
R
+
0.5 V
CL
I
(PK)
V
V
O
( F)
14
13
TL497A
10
8
R1
CO
C
m
[
ton(
m
s)
I I
(PK)
O
V
ripple
)
IO
(PK)
1
2
3
CT
4
5
R2 = 1.2 kΩ
EXTENDED POWER CONFIGURATION
(using external transistor)
Figure 1. Positive Regulator, Step-Up Configurations
POST OFFICE BOX 655303
•
DALLAS, TEXAS 75265
5
TI [ TEXAS INSTRUMENTS ]
