SCALE Driver

2SD106AI Data Sheet

IGBT-Driver.com

Page 9

Collector sense and dimensioning of Rth

The 2SD106AI dual

driver has a collector-

sense

circuit

to

protect

the

power

semiconductors. It is

shown in Fig. 4

Its basic operating

mode can be ob-

tained

from

the

brochure

entitled:

“Description

and

Application

Manual

for Scale Drivers”.

To correspond more

effectively

to

the

turn-on characteristic

of the IGBTs, the

SCALE drivers do not use a static reference voltage to compare the voltage at the

collector. Instead, the reference is used as shown in Fig. 5.

Value Rth

Reaction time Vth1

Vth2

22k

4.9 s

4.8V

3.2V

2.35V (1 Diode)

27k

5.7 s

5.6V

3.9V

3.05V (1 Diode)

33k

6.8 s

6.5V

4.7V

3.25V (2 Diodes)

39k

7.6 s

7.3V

5.6V

4.15V (2 Diodes)

47k

9 s

8.4V

6.8V

5.35V (2 Diodes)

Table 1 Reference resistor, reaction time and turn-off threshold

Notes on Table 1

The values for “Vth1” and “Vth2” are listed in Table 1 as a function of the reference

resistance Rth.

The value in the “Vth1” column corresponds to the voltage threshold after the response

time has elapsed.

The value in the “Vth2” column corresponds to the voltage which is set up statically

across the resistor Rth. This static value is typically reached after between 10 and 15µs.

Rm

V+

V+

Ca

Cx

Rthx

Gx

Ex

Rthx

RGx

Dm (2 x 1N4007)

SCALE Driver Module

IGD 001

4

5

150uA

1.4mA

OVERCURRENT

MEASURING

Fig. 4 Collector-sense circuit principle