All specifications are subject to change without notice.
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TDK-Lambda
CPF1000F 280-*
Series
INSTRUCTION MANUAL
●
Output Voltage Adjustment by applying external voltage
By applying external voltage at the TRIM terminal, output voltage can be adjusted within the same output voltage
adjustment range as the output voltage adjustment by external resistor or variable resistor. For this case, output
voltage can be determined by the formula shown below.
Output Voltage = TRIM Terminal Voltage × Nominal Output Voltage
Load
+
-
External
Voltage
-S
-V
+V
+S
TRIM
Fig.6-4 Output Voltage Adjustment by applying external voltage
For applications other than the above, refer to the trim circuit as shown in fig.6-5 and determine external circuit and
component values.
+S
-S
TRIM
1. 225V
Reference
Voltage
Error Amplifier
32.4k
Ω
R2
7.32k
Ω
R1
Fig.6-5 TRIM Circuit (For the Reference)
6-3. Maximum Output Ripple and Noise
Measured value according to the specified methods based on JEITA-9141 (Clause 7.12 and clause 7.13) which is
described in the following.
Measure according to fig.6-6 connection, based on the basic connection of fig.5-1.
Connect capacitors (C6: ceramic capacitor 2.2
μ
F, C7: refer to table 5-1 for electrolytic capacitor values) at 50mm
distance from the output terminals. Measure at ceramic capacitor (C6) leads as shown in fig.6-6 using coaxial cable
with JEITA attachment. Use oscilloscope with 100MHz frequency bandwidth or equivalent.
+
50mm
+V
-V
Load
As short as possible
Coaxial Cable
1.5m 50
Ω
JEITA Attachment
R:50
Ω
C:4700pF
Oscilloscope
C7
C6
R
C
Fig.6-6 Measurement of Maximum Output Ripple & Noise
Nominal Vo
14V
R1 (k
Ω
)
13
R2 (k
Ω
)
1
