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SN74AC245: Overshoot / undershoot tolerance

Shibuya
Intellectual 2985 points
Part Number: SN74AC245

Hello

My customer is asking about overshoot/undershoot tolerance of the device. They are using competitor's AC245 now and going to replace it to our part. The attached file is waveform of input pin of the current device. Overshoot / undershoot exceeds absolute max rating, but the customer got following guarantee from the competitor (it is not described in datasheet). 

input voltage absolute max rating :  -0.5V  -  VCC+0.5V

Overshoot : VCC + 3.0V (tw = 10ns),    VCC + 1.5V (tw = 100ns)

Undershoot : GND - 3.0V (tw = 10ns),  GND - 1.5V (tw = 100ns)

  * tw (pulse width) : measured at GND - 0.5V and VCC + 0.5V

Do we have this kind of spec?  

Can we accept the overshoot / undershoot voltage to replace the comeptitor part?

Best regards,

Tetsuro

SN74AC245NS.xlsx

  • 0
    TI__Guru* 96681 points

    Hello Shibuya-san,

    The VCC abs max rating is 7V, so the input voltage abs max rating is Vcc + 0.5 = 7.5V -- beyond this value we cannot guarantee that the gate oxide will survive the transient events at the input - there is no time limitation on this requirement.

    The input clamp diode will help to limit the current, and many customers choose to use these diodes to limit the voltage from events like this, but TI doesn't guarantee any type of specific spike suppression or performance from the clamp diodes.