TK112xxB
APPLICATION INFORMATION
INPUT-OUTPUT CAPACITORS
Linearregulatorsrequireanoutputcapacitorinordertomaintainregulatorloopstability.Thiscapacitorshouldbeselected
to ensure stable operation over the desired temperature and load range. The graphs below show the effects of
capacitance value and ESR on the stable operation area.
V
=
OUT
112xxB
2.0 V
C
L
3.0 V
5.0 V
ESR
C = 1 µF
C = 2.2 µF
C = 3.3 µF
C = 10 µF
L
L
L
L
1000
100
1000
1000
1000
100
100
10
100
10
1 0
1 0
STABLE
OPERATION
AREA
STABLE
OPERATION
AREA
STABLE
OPERATION
AREA
STABLE
OPERATION
AREA
1
1
1
1
0.1
0.1
0.1
0.1
0 .01
0.01
0.01
0.01
150
50
150
1
50
100
1
100
1
5 0
100
150
1
5 0
100
150
I
(mA)
I
(mA)
I
(mA)
OUT
OUT
OUT
I
(mA)
OUT
In general, the capacitor should be at least 1 µF (aluminum electrolytic) and be rated for the actual ambient operating
temperature range. The table below shows typical characteristics for several types and values of capacitance. Please
note that the ESR varies widely depending upon manufacturer, type, size, and material.
ESR
Capacitance
Aluminum
Capacitor
Tantalum
Capacitor
Ceramic
Capacitor
1.0 µF
2.2 µF
3.3 µF
10 µF
2.4 Ω
2.0 Ω
4.6 Ω
1.4 Ω
2.3 Ω
1.9 Ω
1.0 Ω
0.5 Ω
0.140 Ω
0.059 Ω
0.049 Ω
0.025 Ω
Note: ESR is measured at 10 kHz.
Page 18
October 1999 TOKO, Inc.
TOKO [ TOKO, INC ]
