LNK302/304-306
LinkSwitch-TN
RF1
D3
L2
D
FB
BP
S
D2
R1
+
C1
AC
INPUT
S
S
L1
C4
C5
C3
R3
DC
OUTPUT
C2
S
D1
D4
Optimize hatched copper areas (
) for heatsinking and EMI.
PI-3750-041509
Figure 6a. Recommended Printed Circuit Layout for LinkSwitch-TN in a Buck Converter Configuration using P or G Package.
D3
L2
RF1
D
S
S
S
S
L1
+
FB
BP
D1
AC
INPUT
C3
C4
C5
D2
C2
DC
OUTPUT
C1
R3
R1
D4
Optimize hatched copper areas (
) for heatsinking and EMI.
PI-4546-041509
Figure 6b. Recommended Printed Circuit Layout for LinkSwitch-TN in a Buck Converter Configuration using D Package to Bottom Side of the Board.
Key Application Considerations
LinkSwitch-TN Selection and Selection Between
LinkSwitch-TN Design Considerations
MDCM and CCM Operation
Output Current Table
Select the LinkSwitch-TN device, freewheeling diode and
output inductor that gives the lowest overall cost. In general,
MDCM provides the lowest cost and highest efficiency converter.
CCM designs require a larger inductor and ultrafast (tRR ≤31 ns)
freewheeling diode in all cases. It is lower cost to use a larger
LinkSwitch-TN in MDCM than a smaller LinkSwitch-TN in CCM
because of the additional external component costs of a CCM
design. However, if the highest output current is required, CCM
should be employed following the guidelines below.
Data sheet maximum output current table (Table ±) represents
the maximum practical continuous output current for both
mostly discontinuous conduction mode (MDCM) and continuous
conduction mode (CCM) of operation that can be delivered
from a given LinkSwitch-TN device under the following
assumed conditions:
±. Buck converter topology.
2. The minimum DC input voltage is ≥70 V. The value of input
capacitance should be large enough to meet this criterion.
3. For CCM operation a KRP* of 0.4.
Topology Options
LinkSwitch-TN can be used in all common topologies, with or
without an optocoupler and reference to improve output voltage
tolerance and regulation. Table 2 provide a summary of these
configurations. For more information see the Application Note
– LinkSwitch-TN Design Guide.
4. Output voltage of ±2 VDC.
1. Efficiency of 715.
6. A catch/freewheeling diode with tRR ≤71 ns is used for MDCM
operation and for CCM operation, a diode with tRR ≤31 ns is
used.
7. The part is board mounted with SOURCE pins soldered to a
sufficient area of copper to keep the SOURCE pin tempera-
ture at or below ±00 °C.
*KRP is the ratio of ripple to peak inductor current.
5
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Rev. J 06/13
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