December 1999 TOKO, Inc.
Page 15
TK716xx
INPUT-OUTPUT CAPACITORS
Linear regulators require input and output capacitors in order to maintain regulator loop stability. The equivalent series
resistance (ESR) of the output capacitor must be in the stable operation area. Since the ESR varies widely between
ceramic and tantalum capacitors, the proper IC must be selected according to the output capacitor used:
The TK716xxS is designed for use with ceramic output capacitors.
(Chip tantalum capacitors and electrolytic capacitors with an ESR below 6
can provide stable operation.)
The TK716xxAS is designed for use with tantalum output capacitors.
The DC electrical characteristics and the specifications of the TK716xxS and TK716xxAS are the same; only the value
of the internal phase compensation is different. Increasing the value of the required output capacitor does not cause
abnormal operation. Increasing the value can improve noise reduction, line regulation, load regulation, and stability.
For stable operation, an input capacitor of 0.22
μ
F or more is required.
Note: it is very important to check the selected manufacturers
’
electrical characteristics. The values of capacitance and
ESR vary from manufacturer to manufacturer, and with product type. A thorough examination is necessary to determine
the characteristics of the capacitor in mass production. The characteristics also vary over temperature. In general, it is
recommended to use as large a value of output capacitance as is practical. Please refer to the following graphs for output
capacitor selection.
APPLICATION INFORMATION
Output side capacitor C
L
= 2.2
μ
F
TK71630S
0 50 100 130
IOUT (mA)
0.1
10
1
100
0.01
Stable area
E
)
TK71630AS
0 50 100 130
IOUT (mA)
0.1
10
1
100
0.01
Stable area
3.3 μF
E
)