Rev. P 06/22

8

LinkSwitch-TN2

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Table 2 (cont). Common Circuit Configurations using LinkSwitch-TN2.

Topology

Basic Circuit Schematic

Key Features

Low-Side

Buck-Boost –

Optocoupler

Feedback

1. Output referenced to input

2. Positive output (V

O) with respect to +VIN

3. Step up/down – V

O > VIN or VO < VIN

4. Optocoupler feedback

- Accuracy only limited by reference choice

- Low cost non-safety rated optocoupler

- No pre-load required

5. Fail-safe – output is not subjected to input

voltage if the internal power MOSFET fails

6. Minimum no-load consumption

LinkSwitch-TN2

PI-7848-031616

+

BP/M

FB

D

S

VO

VIN

+

LinkSwitch-TN2 Layout Considerations

In the buck or buck-boost converter configuration, since the SOURCE

pins in LinkSwitch-TN2 are switching nodes, the copper area

connected to SOURCE should be minimized to minimize EMI within

the thermal constraints of the design.

In the boost configuration, since the SOURCE pins are tied to DC

return, the copper area connected to SOURCE can be maximized to

improve heat sinking.

Figures 9a, 9b and 9c are printed circuit board layout design

examples for the circuit schematic shown in Figure 8. The loop

formed between the LinkSwitch-TN2, inductor (L1), freewheeling

diode (D1), and output capacitor (C2) should be kept as small as

possible. The BYPASS pin capacitor C1 should be located physically

close to the SOURCE (S) and BYPASS (BP) pins. To minimize direct

coupling from switching nodes, the LinkSwitch-TN2 should be placed

away from AC input lines. It may be advantageous to place capacitors

C4 and C5 in-between LinkSwitch-TN2 and the AC input. The second

rectifier diode D4 is optional, but may be included for better EMI

performance and higher line surge withstand capability.

Figure 9a. Recommended Printed Circuit Layout for LinkSwitch-TN2 using P Package.