AN2252

Application circuit description

13/21

The number of turns of primary winding W2 was optimized so as to achieve the turns ratio

W2/ W1 at which the current transformer follows the current gain of the ESBT and thus

provides proportional base current bias for the ESBT over the whole specified input voltage

range and output load range. An overview of the major parameters for each winding is given

in Table 6.

2.3

PCB Layout

The PCB is designed as a single-sided board made of FR-4 material with a 70µm copper

plating, solder and silk screen mask. The assembled board contains only throughhole

components. The outline dimensions are 139 x 61mm. The top side of the assembly can be

seen in Figure 8.

Figure 8.

Assembly schematic

Figure 9. represents the PCB layout of the copper connections. The holes for through hole

components are not shown.

Table 5.

Current transformer core parameters

Description

Value

Shape

R13×7×4.5

Material

Fi 340

Inductance Factor A

2200

Table 6.

Current transformer winding parameters

Start Pin

End Pin

No. of turns

Wire diameter [mm]

Wire material

Inductance [H]

3

5

12

0.355

CuLL

6

1

3

0.355

CuLL