My customer's application uses TXS0108E to interface an OMAP3530 (1.8V) to a 5V RSV232 device. TXS0108E port A, with VCCA at 1.8V, is connected to the OMAP; port B with VCCB at 5V is connected to the 232 driver. In the TXS0108E data sheet, VIL is listed under Recommended Operating Conditions as 0.15V max. OMAP VOL is 0.2V max, so there is a question of whether this configuration will work in the long term. It works in the prototype, but...
1. VIL is listed under Recommended Operating Conditions as 0.15V max. If this is the "recommended" value, what is the real limit? I would expect VIL to be listed under Electrical Characteristics.
2. Is the TXS0108E application described above OK? If not, what is the recommendation?
1. This VIL is the condition we tested under to obtain the VOL and other parameters on the datasheet. To match the VOL max and min listed in the datasheet, a VIL of 0.15V is required. However, the device should work find with a marginally higher VIL of 0.2V. The VOL may be slightly higher than the max in the datasheet, but I don't predict any issues. The performance will be consistent.
2. Yes, the TXS0108 will operate correctly in the application you describe.
Thanks for your response.
I gather from your response to (1) that the TXS0108E VOL is related to its VIL (and current going through the switch). This makes sense.
However, if I were the design engineer being grilled by a panel of reliability engineers at a design review, I would still be very nervous, with no hard numbers or graphs to defend the design.
Is there a VIL vs VOL graph or any other hard data that you can refer me to so that we can eliminate any doubt that it "should work"?
Unfortunately, I don't have of this data handy. I will see what I can do.
I've seen a VOL of <1V up to a VIL of 0.7V. (If theres the opportunity to do some in house testing up to this VIL, this may put the reliability engineers at ease. )
I've also attached an IBIS model of the device, which may be helpful.
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