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Is the OPA549 pad connected to V-?

ito.akio_prm
Prodigy 50 points

Other Parts Discussed in Thread: OPA549

It seems that the contents described in the operational amplifier OPA549 data sheet and the actual operation of the product are not consistent, so please check.

In the POWER SUPPLIES section of the OPA549 data sheet p.8, it is stated that "Package tab is internally connected to V-; however, do not use the tab to conduct current."　However, when using an actual device, V- voltage does not appear on Tab. Also, when measuring the resistance between the V-pin and Tab with OPA549 alone, it is isolated. Am I correct in understanding that the data sheet description is incorrect?

  • 0
    TI__Guru 73511 points

    Without connecting Tab to the negative supply (V-), it is isolated from process substrate by a layer of oxide (Tab floats).  For this reason, for the best OPA549 AC performance, the Tab should be biased externally (at the PCB level) at the negative supply.