An application example

AN4021

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Doc ID 022588 Rev 1

Figure 6.

Maximum reverse losses versus the junction temperature

As shown on Figure 6, the reverse losses increase exponentially with the temperature.

For ST Bipolar diodes, the doping being platinum, the leakage current is very low resulting in

negligible reverse losses.

For Schottky diode, there is a trade-off between the forward voltage drop and the reverse

leakage current. In order to improve the efficiency of a Switch Mode Power Supply, a

Schottky diode with a low forward voltage to the detriment of higher leakage current would

be preferred.

In this case, the heat sink size will be larger in order to keep the junction temperature of the

diode low enough and avoid a thermal runaway phenomenon. (Refer to the AN1542).

0,0

0,4

0,8

1,2

1,6

2,0

2,4

2,8

3,2

3,6

4,0

4,4

4,8

5,2

5,6

6,0

6,4

25

35

45

55

65

75

85

95

105

115

125

135

145

155

P

T (°C)

j