Cosel TUNS300, Руководство по применению

Страница: 32 / 35

11.1 Means of the EMI reduction
■
Fig.2.1 show the recommended circuit example for EN55022 ClassA.
To meet class B or further noise reduction, external components and metal shield should be
changed accordingly. Please refer to the circuit showed on section 11.4.
11.2 Switching frequency noise reduction (200kHz)
■
6dB noise reduction can be achieved either by doubling the values of CY2, CY3 or increase
the values ofL11 and L12.
■
When Cy2, Cy3 is increased to 4,700pF, 0.022uF capacitor should be added as Cy4, Cy5
to keep 3kV isolation between primary and secondary.
As another example, if the value of Cy2, Cy3 are 3300pF, each CY4, CY5
value should be 0.01uF
■
Please note that leakage current would become large if Cy2, Cy3 is increased.
11.3 High frequency band noise reduction (more than 10 MHz)
■
EMI noise over 10 MHz varies depending on position of the external components and
PC board layout.
■
High frequency noise can be reduced by increasing the value of C20 or Y capacitors at
output side (CY4 and CY5).
■
Place the capacitors C20, CY4 and CY5 as close as possible to the power modules.
11.4 EMI measure example
■
Fig.11.1 show the circuit example for EN55022 ClassB.
Fig.11.1
Example of EMI
measure circuit
Table 11.1
List of
component change
for EMI ClassB
requirement
A-29
2.1 Pin configuration
11. Example of which reduces EMI
Applications Manual
TUNS300/500/700
Heatsink
AC1
AC2
+VOUT
-VOUT
-BC FG
F11
+BC
Co
+
Load
C40
AC
INPUT
L11
CY2
CX1 CX2
CY3
L12
Noise
Filter
C11
-S
+S
R
+
C30
TFR1
Cbc
C20
CY1
CY4
CY5
FG
Rating Part name Rating Part name
1 CY2
AC250V/2200pF DE1E3KX222M
(Murata Manufacturing)
AC250V/4700pF DE1E3KX472M
(Murata Manufacturing)
2 CY3
AC250V/2200pF DE1E3KX222M
(Murata Manufacturing)
AC250V/4700pF DE1E3KX472M
(Murata Manufacturing)
3 C20
DC450V/0.68uF
×2parallel AFS450V684K × 2parallel
(OKAYA ELECTRIC INDUSTRIES) DC450V/0.68uF
×3parallel AFS450V684K × 3parallel
(OKAYA ELECTRIC INDUSTRIES)
4 CY4
- - 0.022uF
LE223
(OKAYA ELECTRIC INDUSTRIES)
5 CY5
- - 0.022uF
LE223
(OKAYA ELECTRIC INDUSTRIES)
No. Symbol
Capacitor
for boost voltage
Y capacitor
EN55022 ClassB.
Item
EN55022 ClassA
(Recommended external circuit in Fig. 2.1)
Noise
filter Y capacitor