LNK454/456-458/460
Secondary Side Connections
Maximum Drain Current
The output rectifier and output filter capacitor should be as
close as possible. The transformer output return pin should
have a short trace to the return side of the output filter capacitor.
These currents should not flow through the primary side source
pin currents. The primary side source pin and secondary side
return should be connected with a short trace.
Measure the peak drain current under all operation conditions
including start-up and fault conditions. Look for signs of
transformer saturation (usually occurs at high ambient
temperatures). Verify that the peak current is less than stated in
the Absolute Maximum Ratings section.
Thermal Check
Quick Design Checklist
At maximum output power, both minimum and maximum line
voltage and ambient temperature; verify that temperature
specifications are not exceeded for the LinkSwitch-PL,
transformer, output diodes, output capacitors and drain clamp
components.
Maximum Drain Voltage
Verify that the peak VDS does not exceed 700 V under all
operating conditions including start-up and fault conditions.
Switching
Current Loop
(Primary)
Transformer
U1
Bulk Capacitor
Output Filter
Capacitor
Copper Heat Sink Area
PI-6212-112410
Figure 12. RD-251 PCB Top View.
Switching
Current Loop
(Secondary)
Bulk Capacitor
Connection Between
Primary and Secondary
Transformer
U1
PI-6213-112410
Figure 13. RD-251 PCB Bottom View.
10
Rev. C 10/11
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