March 2001 TOKO, Inc.

Page 11

TK715xxAS

APPLICATION INFORMATION (CONT)

INPUT-OUTPUT CAPACITORS (CONT)

OUTPUT NOISE IMPROVEMENT

An RC filter can be added to the output stage of the regulator to reduce output noise when the input voltage is high and

the output current only makes small changes. Select a regulator with a slightly higher output voltage because the final

output voltage will be reduced by the RC filter. If the output current does make a large change, the output voltage will

change. The following table shows output noise, and output voltage for various values of R

device.

V

RIPPLE REJECTION RATIO

An RC filter can be added to the input stage of the regulator to increase the ripple rejection when the input voltage is high.

Even if the resulting difference between V

output a stable voltage. The voltage dropped across the RC filter depends on the value of the input ripple noise. Select

the value of R

plus 0.2 V.

N

O

I

T

I

D

N

O

C

T

N

E

M

E

R

U

S

A

E

MC

(

R

O

T

I

C

A

P

A

C

E

D

I

S

T

U

P

T

U

O

T

U

O

)S

T

I

N

U

I

T

U

O

R

T

U

O

V

T

U

O

F

µ

0

1F

µ

7

4F

µ

0

0

1F

µC

T

U

O

I

T

U

O

A

m

0

4

-

0

2

=0

V

0

0

5

.

3V

µ

0

1

2V

µ

0

5

1V

µ

0

3

1S

M

R

E

S

I

O

N

A

m

0

20

1

W

V

6

9

2

.

3V

µ

6

7V

µ

0

5V

µ

0

4S

M

R

A

m

0

38

.

6

W

V

7

8

2

.

3V

µ

8

8V

µ

5

5V

µ

8

4S

M

R

A

m

0

41

.

5

W

V

6

6

2

.

3V

µ

0

0

1V

µ

0

6V

µ

8

4S

M

R

TK715xxA

VOUT

COUT

VIN

CL = 2.2 µF

LOAD ADJ.

IOUT = 20, 30, 40 mA

ROUT

TK715xxA

VOUT

CL

CIN

VIN

LOAD ADJ.

IOUT = 20, 30, 40 mA

RIN