AN2002

Using the Demoboard for the TD350 Advanced IGBT Driver

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2.1 Input stage

The TD350 can be driven by either a pulse transformer or an optocoupler. The demoboard is set up to

use an optocoupler. The TD350 IN pin is clamped to 5V by a zener diode D2 and its bleeding resistor

R11=10K (see demoboard schematic on Figure 4). To interface the demoboard with the system, the IN1

pin of the input connector can simply be connected to a low-side optocoupler, as show on Figure 5. An

optional filtering capacitor can be added (for instance 47pF) in the event of a highly noisy environment,

although the TD350 already includes a filtering on input signals and rejects signals smaller than 100ns

The demoboard can be modified to be driven by a pulse transformer by implementing the optional

components R2, R3, R4 and C8. The principle of operation with a pulse transformer is explained in

AN1944.

Figure 2: Demoboard layout

Figure 3: Demoboard PCB: Silk-screen, top-layer and bottom-layer previews