TK717xxS
APPLICATION INFORMATION (CONT.)
INPUT-OUTPUT CAPACITORS
Linear regulators require input and output capacitors in order to maintain the regulator’s loop stability. The equivalent series
resistance (ESR) of the output capacitor must be in the stable operation area. However, it is recommended to use as large
a value of capacitance as is practical. The output noise and the ripple noise decrease as the capacitance value increases.
The IC is never damaged by enlarging the capacitance.
ESR values vary widely between ceramic and tantalum capacitors. However, tantalum capacitors are assumed to provide
more ESR damping resistance, which provides greater circuit stability. This implies that a higher level of circuit stability
can be obtained by using tantalum capacitors when compared to ceramic capacitors with similar values. The IC provides
stable operation with an output side capacitor of 0.22
mF
(V
OUT
³
2.0 V). If the capacitor is 0.1
mF
or more over its full range
of temperature, either a ceramic capacitor or tantalum capacitor can be used without considering ESR (V
OUT
³
2.0 V).
For output voltage device
³
2.0 V applications, the recommended value of CL
³
0.22
mF.
For output voltage device
³
1.5 V applications, the recommended value of CL
³
0.47
mF.
For load current
£
0.5 mA, increase the output capacitor to 1
mF.
The input capacitor is necessary when the battery is discharged,
the power supply impedance increases, or the line distance to the
power supply is long. This capacitor might be necessary on each
individual IC even if two or more regulator ICs are used. It is not
possible to determine this indiscriminately. Please confirm the
stability while mounted.
VOUT
CIN = 0.22
µF
CL = 0.22
µF
CN = 0.01
µF
STABLE OPERATION AREA vs. VOLTAGE, CURRENT AND ESR
VOUT = 1.5 V - 1.9 V
100
100
VOUT = 2.0 V
100
VOUT = 3.0 V
100
VOUT = 4.0 V
100
VOUT = 5.0 V
10
10
10
10
10
ESR (Ω )
ESR (Ω )
ESR (Ω )
ESR (Ω )
1
1
1
1
ESR (Ω )
STABLE AREA
CL = 0.1
µ
F
STABLE AREA
CL = 0.1
µ
F
STABLE AREA
CL = 0.1
µ
F
STABLE AREA
CL = 0.1
µ
F
STABLE AREA
CL = 0.1
µ
F
1
0.1
0.1
0.1
0.1
0.1
0 .01
0
50
100
IOUT (mA)
All Stable
CL
≥
1.0
µ
F
150
0 .01
0
50
100
IOUT (mA)
All Stable
CL
≥
0.22
µ
F
150
0 .01
0
50
100
IOUT (mA)
150
0 .01
0
50
100
IOUT (mA)
150
0 .01
0
50
100
IOUT (mA)
150
Please increase the output capacitor value when the load current is 0.5 mA or less. The stability of the regulator improves
if a big output side capacitor is used (the stable operation area extends).
For evaluation
KYOCERA CM05B104K10AB, CM05B224K10AB, CM105B104K16A, CM105B224K16A,CM21B225K10A
MURATA
GRM36B104K10, GRM42B104K10, GRM39B104K25, GRM39B224K10, GRM39B105K6.3
Page 10
October 2001 TOKO, Inc.
TOKO [ TOKO, INC ]
