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Need suggestion for a OP Amp with short circuit protection feature

PYTsai
Genius 9275 points
Other Parts Discussed in Thread: TLV9002, OPA2990

Hi 

We are looking for an OP AMP with short circuit protection feature, can you help recommend.

the requirement are below 

1. output current 20mA, 1MHz GBW,

2. single supply VCC > 15V，

3. with output short circuit protection 

Thanks!

  • 0
    Guru 140200 points

    Hi Pytsai,

    the most OPAmps have a short circuit protection.

    What do you actually mean by "20mA"? Minimum guaranteed output current? Or maximum output current during current limit?

    By the way, there are other methods to limit the output current to a very precise value. For instance, by putting a current limiting resistor into the feedback loop as shown in this training video:

    Kai

  • 0 in reply to kai klaas69
    TI__Genius 9275 points

    Hi Kai,

    The OP AMP need to be able to source or sink 20 mA continuously. while if in short circuit condition happen continuously, the op AMP can not be damaged. 

    How do i know from datasheet that if an op amp have short circuit protection or not ?

  • 0 in reply to PYTsai
    Guru 140200 points

    Hi Pytsai,

    it's usually specified in the datasheet.

    Let's take the TLV9002 as an example: Open the datasheet and look at section 7.1 (absolute maximum ratings), section 7.10 (bottom of page 16), figure 33 and section 8.3.1.

    Kai

  • Former Member
    0 Former Member in reply to PYTsai

    Hello PYTsai,

    Kai is correct.  Most op amps have continuous short-circuit output capabilities.  This means that they are capable of continuously being under short circuit conditions at the output.  There is no time limitation.  See, for example, the datasheet of the OPA2990, which is a good candidate for you.

    Also of value is the note regarding excessive heating.  You can use this resource for further help calculating expected heat.

    From figure 44 of the same datasheet, you can see that the short-circuit output current varies across temperature.  There will be some variation in this value from device to device as this is a typical specification and not guaranteed by a max/min.  However, I think this will have plenty of margin for you application.

    Please check figures 14 and 15 of the datasheet to ensure the output swing is close enough to rail.  Note that the load is connected to Vs/2 for these cases.  So you may have better output swing to GND if your load is tied to GND.

    Regards,

    Daniel