TS-7970 Errata: Difference between revisions
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| Fixed in REV C | | Fixed in REV C | ||
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If the console jumper is not installed the silabs has USB VBUS, but no data signals. This puts the USB device into a locked up state while it waits to communicate on this bus. | If the console jumper is not installed the silabs has USB VBUS, but no data signals. This puts the USB device into a locked up state while it waits to communicate on this bus. Due to this lockup it is unable to monitor voltages and turn on the SW_5V to the reset of the board. The fix is to disconnect VBUS from the silabs which is done on the REV C PCB. A cable without VCC can be made to work around the issue, or submit an RMA. | ||
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Revision as of 11:54, 13 February 2017
| Issue | Status | Description |
| RS232 prevents booting on REV A | Workarounds available, fixed in REV B |
Early TS-7970 REV A boards may fail to boot if RS232 is connected before the board is powered. A small amount of RS232 idle negative voltage leaks from the transceiver to the FET controlling the switched 5V. The FET will not toggle while the output has a negative voltage, so the 5V rail never comes up. If this is a concern or if the issue is seen, we can rework the board to have a 2.5ohm resistor from SW_5V to 5V_A on U47 pins 4 and 5. REV A boards shipped after 01/13/2016 include this fix. |
| Boot is prevented if the USB Device port (not host) is plugged in without the console enable jumper. | Fixed in REV C |
If the console jumper is not installed the silabs has USB VBUS, but no data signals. This puts the USB device into a locked up state while it waits to communicate on this bus. Due to this lockup it is unable to monitor voltages and turn on the SW_5V to the reset of the board. The fix is to disconnect VBUS from the silabs which is done on the REV C PCB. A cable without VCC can be made to work around the issue, or submit an RMA. |