Application constraints

AN3432

12/24

Doc ID 019041 Rev 1

Figure 8.

STPS20L45C and STPS2045C conduction losses versus junction

temperature

For a first consideration the lower is the forward voltage the higher is the efficiency. However,

for a Schottky diode, a lower forward voltage causes a higher leakage current. This is its

main technological trade off.

Diode reverse losses

When the diode is reversed bias, all the cells bridged by the diode generate photocurrent.

Most of the time, in bypass application, the leakage current induces reverse losses. They

increase with the junction temperature and can be calculated using Equation 13.

Equation 13

0

1

2

3

4

5

6

7

8

9

10

-40

-20

0

20

40

60

80

100

120

140

160

180

200

Pcond (W)

STPS2045C

STPS20L45C

I sc = 8 A

Tj (°C)

)

C

125

Tj

(

c

R

R

R

j

rev

e

)·

C

125

,

V

(

I·

V

)

T

(

P

°

−

°

=