TL497A

SWITCHING VOLTAGE REGULATORS

SLVS009D – JUNE 1976 – REVISED JULY 1999

7

POST OFFICE BOX 655303

APPLICATION INFORMATION

VI

VI

RCL

14 13

10

8

TL497A

12

3

4

5

CT

R1

R2 = 1.2 k

Ω

CO

RCL

14

13

10

8

R1

CT

L

VO

L

VO

12

3

4

5

DESIGN EQUATIONS

I

(PK) +

2I

O

max 1

)

V

O

V

I

L(

mH) +

V

I

I

(PK)

ton(ms)

C

T

(pF)

[ 12 ton(ms)

R1

+ V

O

–1.2 V k

W

Choose L (50 to 500

µH), calculate

ton (10 to 150 µs)

R

CL +

0.5 V

I

(PK)

C

O

(

mF) [ ton(ms)

V

I

V

O

I

(PK) )

I

O

V

ripple

(PK)

EXTENDED POWER CONFIGURATION

(using external transistor)

†

R2 = 1.2 k

Ω

†

TL497A

CO

BASIC CONFIGURATION

(Peak Switching Current = I(PK) < 500 mA)

† Use external catch diode, e.g., 1N4001, when building an inverting supply with the TL497A.

Figure 3. Inverting Applications