An issue was recently discovered on the PicoZed 7015/7030 SOMs where we are pulling the enable pin on one of the on board regulators to a voltage higher than the maximum pin rating.
The TPS54618 is used to provide core power to the SOM. This device is powered by 5V from the carrier board. In our schematic, we are pulling the ENABLE pin on this device up to Vin through a 10k resistor. This particular device has an internal pullup on the ENABLE line, making the external pullup unnecessary. The maximum voltage rating for the ENABLE pin is 4V, which is exceeded when pulling up the pin to Vin through the 10k resistor. In extreme cases, applying this higher voltage to the pin may cause the ENABLE to short to ground, resulting in the inability to turn on this regulator.
The easiest fix for this issue is to remove R52. Interoperability with our carrier cards is not affected as we pull this line low to disable and allow it to float to enable. Another option is to use a voltage divider on the carrier card to limit the maximum voltage on the pin. The SVDK kit ships with both a 7015 and a carrier, when used together this issue is not present (a voltage divider is used on the carrier that limits the maximum voltage the pin sees). R52 should still be removed from these SOMs as well though as it’s population in the design of the SOM is still an error. Please remove this resistor from all 7015 and 7030 SOMs, if you feel you cannot perform this rework, please contact Avnet online or through your local Avnet resource to arrange for us to perform this rework for you at no charge.
