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004-02 / 20070523 / ea122_jbw.fm
• All specifications are subject to change without notice.
Characteristics, Functions, and Applications
RIPPLE NOISE MEASUREMENT CONDITIONS
SERIES OPERATION (TO INCREASE OUTPUT VOLTAGE OR
TO OBTAIN SEPARATE ±OUTPUT)
When the output voltage of a single power supply is insufficient,
several power supplies can be connected in series in order to
obtain a higher voltage or separate ±outputs.
If power supplies A and B in the illustration below are 5V each, a
10V output can be obtained in this connection. It should be noted
that, however, the output current is limited to the lower rated cur-
rent value of the power supplies A and B. There is no problem if
the voltages of A and B are different from each other.
D1 and D2 in the illustration designate diodes for preventing
reverse voltage application. They are provided for preventing inter-
nal components of the power supply having the lower rated voltage
from being damaged by an applied reverse voltage caused by a
short circuit in the load or the like.
Use diodes which meet the following requirements:
Reverse withstanding voltage: Over twice that of the combined
output voltage
Forward current: Over twice that of the output current
Forward voltage drop:As small as possible
(e.g. Shottkey diode, etc.)
SERIES CONNECTION FOR INCREASING OUTPUT VOLTAGE
INSULATION AND WITHSTAND VOLTAGE TESTS
The insulation and withstand voltage tests may cause deteriora-
tion. Care must be taken for execution of the tests. The potential
must be equal among input, output, and FG (frame ground) termi-
nals. It is preferable to use testers that gently start up at the test-
ON and automatically discharge charged energy at the test-OFF.
Manual discharging after the tests should be through a resistor
around 100kΩ to 1MΩ (Do not perform discharging at low imped-
ance. It may cause deterioration.)
In any case, take full countermeasures for electric-shock preven-
tion.
OTHER CONDITIONS
• Unless conditions are otherwise specified in the specifications or
standards, 25°C and rated input-output should be applied.
L
+
C
1
C
2
Output connector
Load
Output ripple and noise measurement point (20MHz)
C
1
C
2
L
: 100µF Electrolytic capacitor
: 0.1µF Film capacitor
: 150mm
D1
D2
Power supply A
Power supply B
Load
∗ For obtaining separate ±outputs, (A) should be zero voltage.
(A)∗
+
–
+
–