Improvement of turn-off capability for new high-temperature TRIACs

AN2777

6/13

Doc ID 14748 Rev 1

2

Improvement of turn-off capability for new high-

temperature TRIACs

As shown previously (for example in Figure 5), (dI/dt)c drastically decreases with the die

temperature. For example, the BTB12-600CW capability would be 35% lower at 150 °C

depends on the rms load current (as given in the equation below), the TRIAC at 150 °C

would be able to drive loads with 35% lower power.

Equation 1

Of course, such a load power derating cannot be accepted. Compensating for this derating

would lead appliance designers to use a higher current TRIAC, if they wanted to increase

the working temperature. STMicroelectronics has improved the design of the device to

improve the TRIAC turn-off capability.

The following simulation indicates the results that can be obtained with the design

improvements. Figure 6 gives the simulation result of two different devices. One is able to

turn-off, the other one not.

Figure 6.

Simulation results for two different TRIACs

This breakthrough design has strongly improved device performance for high temperature

applications.

The new high-temperature TRIAC family features very high commutation capabilities. For

example, Figure 7 compares the BTB12-600CW with a new high-temperature T1235H-6

device. This figure shows that the turn-off capability is approximately four times higher with

the new device over the whole temperature range.

3

)

Hz

(

)

A

(

RMS

)

ms

/

A

(

OFF

10

F

2

2

I

dt

/

dI

·

·

·

·

-

π

=

1

2

3

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

9.970E-04

9.990E-04

1.001E-03

1.003E-03

1.005E-03

1.007E-03

IT (A)

time (s)

Improved structure

Reference structure