Hi All,
We have a TXS0206 issue ... in simple SD card buffer application.
Although our card can potentially have different VCCA/B, the supplies are connected in this case, so VCCA = VCCB = 3.3V
The A side signals are all LVCMOS33, and the SD card is 3.3V
WP is left unconnected.
If EN = 1, CD = pulled high, we can see CLKA propagated to CLKB correctly.
However, for the purposes of the issue, EN can be high or low.
All is well, until CD is switched low, either when an SD card is inserted, or with a temporary jumper, at which point the part crowbars the supplies, and with no supply protection, kills the part. This happens regardless of whether CD is low at power-up, or if CD is switched low with power on.
On further investigation, and live part, a 27R resistor between CD and GND is pulled to 2.5V, i.e. sourcing ~100mA
This happens even if all the other signals are tristate.
We've looked at the obvious things (shorts, layout etc), and there appears to be nothing obvious.
The only visible issue (in relation to earlier posts), is that some of the signals (DAT1, DAT2) are unused and floating on both ports. I don't see why that would be an issue, given the on-chip pullups.
It's possible it's a manufacturing issue, but it occurs on multiple boards.
Has anyone else seen anything similar?
Thanks
Julie