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# OPA192: Questions about ESD protection diode placed between IN- and VDD terminal

Part Number: OPA192

One of my customers is evaluating OPA192 for their new products.
At this moment, they have the following questions.

Q1. We can see a ESD diode is placed between IN- and VDD terminal in Figure 65 on page 29 of OPA192 datasheet (Ver SBOS620E).
How much is the allowable DC current value of the ESD diode? Is it 10mA?

Q2. If IN- input current is less than 10mA as Absolute maximum ratings table, Is the diode not damaged even if IN- voltage is higher than VDD voltage + 0.5V?

Q3. Can IN- terminal be applied a voltage less than 0.5V when VDD voltage is 0V?

Best regards,

Kazuya.

• Hi Kazuya,

yes, limiting the input current <10mA will make the OPA192 survive situations when the input voltage goes negative. But the OPA192 will not work properly then, as the common mode input voltage range for standard operation is  (V–) – 0.1V...(V+) + 0.1V.

Kai

• Hi Nakai-san,

Q1: Agreed with Kai, 10 mA is the maximum.

Q2: The diode voltage will change over temperature.  At colder temperatures, the forward voltage of the diode will be higher for the same current.  So, if you force 10 mA of current, the voltage can be as high as 1 V at -40 C; on the other hand, it can be as low as 0.3 V at 125C.  It is the current that will cause failures, so as long as it is kept to < 10 mA, the voltage can be higher than 0.5 V and the device will still survive.

Q3: Yes, the same limitation applies when the supply voltage is 0 V.  The device will survive as long as current is kept < 10 mA.  The voltage across the diode at a fixed current will change over temperature, same as I mentioned above.  If you force 0.5 V, at 125C, you may get > 10 mA current, which would violate the specification.

Best Regards,
MIke

• Hi Michael and Kai,