APL78L05 データシートの表示（PDF） - Anpec Electronics
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APL78L05 Datasheet PDF : 17 Pages
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APL78L05/12
Application Information
The APL78L05/12, series of fixed voltage regulators, are
designed with thermal overload protection that shuts down
the circuit when subjected to an excessive power overload
condition. In addition, the APL78L05/12 have the func-
tion of internal short circuit protection to limit the maxi-
mum current the circuit will pass.
In many low current applications, compensation capaci-
tors are not required. However, it is recommended that
the regulator input will be bypassed with a capacitor if the
regulator connects to the power supply filter with long
wire lengths, or if the output load capacitance is large. The
input bypass capacitor should be selected to provide
good high-frequency characteristics to insure stable
operation under all load conditions. If the value of the
capacitor is greater than 0.33µF, the capacitor with tan-
talum or mylar, or other capacitor having low internal im-
pedance at high frequencies should be chosen. The by-
pass capacitor should be mounted with the shortest pos-
sible leads directly across the regulators input terminals.
Good construction techniques should be used to mini-
mize ground loops and lead resistance drops since the
regulator has no external sense lead. Bypassing the out-
put is also recommended.
Input
APL78L05
For example, a 100mA current source would require R to
be a 50Ω, 1/2W resistor and the output voltage compli-
ance would be the input voltage less 7V.
+20V
APL78L05
0.33µF
7
2
6 MC1741
3
4
0.33µF
20V
6.5
MPSU55
MPSA70
+VO
10K
10K
-VO
Figure 2. ±15V Tracking Voltage Regulator
+VI
0.33µF
-VI
0.33µF
APL78LXX
APL79LXX
+VO
0.1µF
0.1µF
-VO
0.33µF
R
lO
Constant
Current to
Grounded
Load
Figure 3. Positive and Negative Regulator
Figure 1. Current Regulator
The APL78L05 regulators can also be used as a cur-
rent source when connected as above. In order to mini-
mize dissipation, the APL78L05 is chosen in this
application. Resistor R determines the current as be-
low :
IO =
5.0V
R
+ IB
I =3.8mA over line and load changes
B
Copyright © ANPEC Electronics Corp.
8
Rev. A.11 - Jun., 2011
www.anpec.com.tw
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