※Contact TDK-Lambda concerning items not mentioned or items which are not clear.
3-6 Output Ripple Noise Voltage Measurement Method
When measuring the output ripple noise voltage of this converter, the value differs greatly, depending on the measurement method.
Measurement is to be made close to the output terminal, do not make a loop when connecting the probe in order to avoid
picking up magnetic flux. Also, note that the measured value will vary greatly as a result of the frequency band of the ripple
voltmeter or oscilloscope used for measuring. The TDK ripple noise measurement is made according to the method shown in
Figure 3-6.
Load
+Vout
-Vout
Cout
DC
Input
+Vin
-Vin
Oscilloscope
Bw：100MHz
25mm
R
C
1.5m 50Ω Coaxial Cable
JEITA attachment
R＝50Ω C＝0.1μF
3.3V，5V output ： Cout＝22μF
12V，15V output ： Cout＝0.1μF
Fig. 3-6 Ripple Noise Voltage Measurement Circuit
【Caution when Adding External Capacitor Cout】
External capacitor Cout may influence the output ripple voltage by the ESR and ESL and inductance of the wiring. In particular,
caution is required if low ESR ceramic capacitors, etc. are connected, resonance will occur between the capacitor and the wiring
inductance and the ripple component may increase.
