TL497A
SWITCHING VOLTAGE REGULATORS
SLVS009D – JUNE 1976 – REVISED JULY 1999
APPLICATION INFORMATION
R
L
CL
V
I
DESIGN EQUATIONS
V
O
14 13
10
5
8
R1
†
I
2 I max
O
1
(PK)
V
I
C
TL497A
O
V
I
L ( H)
t
( s)
on
R2 = 1.2 kΩ
I
1
2
3
4
(PK)
V
O
Choose L (50 to 500 µH), calculate
(10 to 150 µs)
C
T
t
on
C (pF)
T
12 t ( s)
on
BASIC CONFIGURATION
(Peak Switching Current = I
< 500 mA)
L
(PK)
R1
V
– 1.2 V
O
k
0.5 V
R
R
CL
CL
I
(PK)
V
I
V
I
I
I
(PK)
(PK)
O
V
O
V
C
( F)
t
( s)
on
O
R1
ripple
14
13
10
5
8
†
TL497A
C
O
R2 = 1.2 kΩ
1
2
3
4
V
O
C
T
EXTENDED POWER CONFIGURATION
(using external transistor)
†
Use external catch diode, e.g., 1N4001, when building an inverting supply with the TL497A.
Figure 3. Inverting Applications
7
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