SCALE Driver

2SD315AI Data Sheet

Page 10

INTELLIGENT POWER ELECTRONICS

Collector sense and dimensioning of Rth

The 2SD315AI dual driver has a collector-sense circuit to protect the power semicon-

ductors. It is shown in Fig. 4

Its basic operating mode can be obtained 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.

In order to ensure that the 2SD315AI can be applied as universally as possible, the

components Ca (response time capacitor) and Rm (attenuation resistor) are not

integrated in the driver as shown in Fig. 4, but must be connected externally. Whereas

Ca can be matched to the specific application, a standard value of 180Ω is

recommended for Rm. The ground terminal of Ca should be connected to the COMx

pin.

Rm

180R

Ca

Cx

Rthx

Gx

Ex

Rthx

RGx

Dm

(2 x 1N4007)

SCALE Driver 2SD315A

150uA

1,4mA

OVERCURRENT

MEASURING

+VDD

+VDD

COMx

Fig. 4 Collector-sense circuit principle