OPA4990: OPA4990IRUCR

Hi Minglai,

footnote 2 of "absolute maximum ratings" given in section 6.1 of datasheet says

"(2) Short-circuit to ground, one amplifier per package. Extended short-circuit current, especially with higher supply voltage, can cause
excessive heating and eventual destruction. See the Thermal Protection section for more information."

So, yes, 80mA is the short-circuit current per channel but the short-circuit time is "continuous" only for one channel at a time and only if the OPAmp isn't overheating by this.

Assume your OPAmp is powered by +/-20V and the output is shorted to signal ground. Then a heat of 20V x 80mA = 1.6W has to be dissipated within the OPA4990. With a junction to ambient thermal resistance of 54°/W of WQFN package the die will heat up 54°C/W x 1.6W = 86°C over the ambient temperature. And if your ambient temperature is 85°C then your OPAmp will be barbecued at a die temperature of 85°C + 86°C = 171°C. And this with only one short-circuited output.

A good remedy against frequently happening short-circuits during normal operation is to add a current limiting resistor to the output. And/or decrease the supply voltage to a reasonable value.

Kai

Hello Minglai,

I agree with Kai's statements. to answer in order.

1) Yes

2) Slightly if op amp limits the current or significantly if the load does. In any case, there is less voltage dropped across the op amp; less power dissipated

3) It doesn't. OL out Z applies in linear operation range, shorts are not linear operation. 

4) Yes,

Hello Minglai, 

Looks like the RUC is out of stock but you are able to request samples of the RTE package: 

Your regional TI field office should be able to get samples to you. 

All the best,
Carolina