tk71547as Toko Inc., tk71547as Datasheet - Page 11

• Manufacturer Part Number: tk71547as
• Description: Low Dropout Voltage Regulator
• Manufacturer: Toko Inc.

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.
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.
March 2001 TOKO, Inc.
I
O
U
T
=
2
3
4
2
0
0
0
I
0
O
M
m
m
m
U
-
T
E
A
A
A
4
A
0
IN
S
V
m
such that the lowest value of V
U
IN
A
R
= 4.0 V, C
E
M
E
N
6
5
1 W
T
R
8 .
1 .
0
0
V IN
O
R IN
C
U
W
W
T
O
IN
N
APPLICATION INFORMATION (CONT)
= 10 mF (aluminum electrolytic), C
D
T I
O I
N
3
3
3
3
5 .
2 .
2 .
2 .
V
0
9
8
6
O
TK715xxA
U
0
6
7
6
V IN
IN
T
V
V
V
V
at the regulator (after the RC filter) and V
IN
C IN
plus the ripple noise after the RC filter (peak to peak) is the output voltage
2
1
O
7
8
1
1
0
6
8
0
U
TK715xxA
0
0
µ
µ
T
µ
µ
µ
V
V
F
P
V
V
V OUT
U
T
C L = 2.2 µF
S
D I
R OUT
E
1
4
5
5
6
OUT
5
0
5
0
C
7
0
A
µ
µ
µ
µ
µ
V OUT
V
V
V
P
F
= (see table), R
V
A
C OUT
C
T I
C L
O
R
1
1
4
4
4
C (
0
3
0
8
8
0
0
O
µ
µ
µ
LOAD ADJ.
I OUT = 20, 30, 40 mA
LOAD ADJ.
I OUT = 20, 30, 40 mA
U
µ
µ
V
V
V
T
V
)
F
OUT
OUT
is small the TK71533AS will
= (see table)
OUT
U
R
R
R
R
and C
N
µ
M
M
M
M
TK715xxAS
T I
F
S
S
S
S
S
OUT
using a 3.5 V
N
C
O
Page 11
O
S I
U
T
E