RDK-257 Power Integrations, RDK-257 Datasheet - Page 11

• Manufacturer Part Number: RDK-257
• Description: REFERENCE DESIGN LINKSWITCH-PH
• Manufacturer: Power Integrations
• Series: LinkSwitch®-PHr

Specifications of RDK-257

• Design Resources: RDR-257
• Current - Output / Channel: 330mA
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 36V
• Voltage - Input: 90 ~ 265VAC
• Utilized Ic / Part: LNK405EG
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 596-1424

Layout Considerations
Primary Side Connections
Use a single point (Kelvin) connection at the negative terminal of
the input filter capacitor for the SOURCE pin and bias returns.
This improves surge capabilities by returning surge currents
from the bias winding directly to the input filter capacitor. The
BYPASS pin capacitor should be located as close to the
BYPASS pin and connected as close to the SOURCE pin as
possible. The SOURCE pin trace should not be shared with the
main power MOSFET switching currents. All FEEDBACK pin
Figure 11. RD-193 7 W Layout Example, Top Layer.
www.powerint.com
N
L
RV1
F1
Input EMI Filter
Copper Area for
L1
Heat Sinking
L2
R3
C2
R2
R16
R14
Bulk Capacitor
C9
L3
R24
C14
VR3
components that connect to the SOURCE pin should follow the
same rules as the BYPASS pin capacitor. It is critical that the
main power MOSFET switching currents return to the bulk
capacitor with the shortest path as possible. Long high current
paths create excessive conducted and radiated noise.
Secondary Side Connections
The output rectifier and output filter capacitor should be as
close as possible. The transformer’s output return pin should
have a short trace to the return side of the output filter capacitor.
C3
VR1
C8
Clamp
D8
R10
D1
FL1
U1
C6
C12
BYPASS Pin
LNK403EG
Capacitor
T1
C7
2
LNK403-409EG/413-419EG
1
C5
Transformer
6
V
3
4
C4
5
V
Capacitors
Output
Filter
PI-5987-060110
Rev. B 11/10
11