Application schematic

AN2123

12/15

IGBT modules suitable for TD351 are indicated in bold. For the FP50R12KE3 and 6MBI75S-120

modules, the source (charging) peak current will be limited to 0.75 A in worst-case conditions instead of

the theoretical 0.8 A or 0.9 A peak values; this usually doesn’t affect the application performance.

An external buffer will be required for higher power applications.

A reference schematic is shown in Figure 17. It uses a bootstrap principle for the high-side driver supply.

A very simple voltage regulator is used in front of the TD351 high-side driver. In this way, the bootstrap

supply voltage can be made significantly higher than the target driver supply, and the voltage across the

Cb bulk capacitor can exhibit large voltage variations during each cycle with no impact on the driver

operation.

Gate resistor Rg depends on the IGBT. It should be noted that the applications only use two supplies

referenced to the ground level.

Table 1.

Recommended gate resistors

Eupec:

FPxxR12KE3

15

25

40

50

75

A

Rgate

75

36

27

18

5

Ω

Ipeak

0.2

0.4

0.55

0.8

3A

Fuji:

6MBIxxS-120

10

15

25

35

50

75

100

A

Rgate

120

82

51

33

24

16

12

Ω

Ipeak

0.12

0.2

0.3

0.45

0.6

0.9

1.3

A

App. Power

1.5

234

57

11

15

kW