TK717xxS
TEST CIRCUIT
A
VIN
IIN
CIN = 0.22 µF
VIN
GND
A
VCONT V ICONT
On/Off Control
VOUT
CL = 0.22 µF
V
IOUT
CN = 0.01 µF
Noise Bypass (VREF)
TYPICAL PERFORMANCE CHARACTERISTICS
Noise Performance
TK71730S NOISE vs. CN
300
CL = MLCC
250 ♠
200
♦ CL = 0.2 µF
CL = 0.4 µF
♦
CL = 1.0 µF
♠ CL = 2.2 µF
CL = 10 µF
150
100
CL = TANTALUM
50
0
0
IOUT = 30 mA
BPF = 400 Hz ~ 80 kHz
10 100 1000 10000 100000
CN (pF)
NOISE vs VOUT
70
IOUT = 30 mA
CN = 0.01µF
60
CL = 1.0 µF (TANTALUM)
50
40
30
20
BPF = 400 Hz ~ 80 kHz
10
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
VOUT (V)
NOISE vs. IOUT
70
CN = 0.01 µF
65
60
55
50
45
40 ♦
♦ CL = 0.22 µF
CL = 0.47 µF
CL = 1.0 µF
♠ CL = 2.2 µF
CL = 10 µF
CL = TANTALUM
35
♠
30
0 25 50 75 100 125 150 175 200
IOUT (mA)
NOISE vs. IOUT
NOISE vs. FREQUENCY
70
10
CN = 0.01 µF
TK71730S
65
CIN = 10 µF
60
♦ CL = 0.22 µF
CL = 0.47 µF
CL = 0.22 µF (MLCC)
IOUT = 10 mA
55
CL = 1.0 µF
1
♠ CL = 2.2 µF
CN = 0.01 µF
50
CL = 10 µF
45
♦
40
♠
35
CL = MLCC
0.1
CN = 0.10 µF
30
0.01
0 25 50 75 100 125 150 175 200
0.01 0.1
1
10 100
IOUT (mA)
FREQUENCY (kHz)
Page 6
For better noise reduction it is
more effective to increase CN
without increasing CL.
The recommended CN capaci-
tance is 6800 pF or 0.01 mF.
As the output voltage increases,
the noise will also increase.
January 2002 TOKO, Inc.