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OPA2365-Q1: Reliability with Vs=5.5V

Antonio Fadhel
Genius 9410 points
Part Number: OPA2365-Q1
Other Parts Discussed in Thread: LMH6619-Q1, OPA2365

Hi Team,

The OPA2365-Q1 datasheet lists Vs=5.5V as the test condition for some of the electrical specs. However, 5.5V is both the max recommended voltage and abs max of the device. Is 5.5V nominal supply operation acceptable? Or should it be lowered to ensure that with supply DC setpoint inaccuracies and any potential transients it stays below this voltage?

Also, what would be the expected reliability impact of running with a 5.5V supply?

Thanks,

Antonio

  • 0
    Guru 279070 points

    The 5.5 V limit indeed exists to allow a nominal 5 V supply with loose tolerances; 5.5 V is the worst case of a 5 V ± 10 % supply.

    With an absolute maximum rating of 5.5 V, a voltage of 5.501 V might, in theory, blow the device up. Can you guarantee that your power supply will never go that high?

    The AHC logic family Designer's Guide says:

    Input voltages greater than 7 V must be avoided to preclude damage to the gate oxide of the input stage. This damage is not necessarily permanent, but will adversely affect the expected lifetime of the circuit. The gate oxide of AHC devices is only 200 Å thick. An input voltage of 7 V corresponds to a field strength over the gate oxide of 350 kV/cm. Although breakdown of the oxide is expected only at input voltages above 10 V, electrons tunnel increasingly into the gate oxide at field strengths greater than 350 kV/cm, influencing characteristics of the transistors and causing failure.

    I do not know what the gate oxide thickness of the OPA2365-Q1 is. Anyway, with an opamp, this degradation will certainly affect the analog characteristics.

    If you actually need voltages higher than 5 V, you should use another opamp like the LMH6619-Q1.

  • 0
    Guru 140200 points

    Hi Antonio,

    if you can guranatee that the supply voltage never rises above 5.5V, not even very briefly, then you can supply the OPA2365 with 5.500V. But usually you need to have some headroom for limited input ripple rejection, output regulation spikes, manufacturing tolerances of voltage regulation, etc. Then you should use a standard voltage regulator delivering a +/-5% toleranced 5.0V supply voltage.

    Kai