FMEA perspective open short Phenomenon.

[takashitakahash]

Hi community.

FMEA perspective.

1. About the unused terminal of 10 k-pulldown are USB_DCAP, USBx_VBUS, USBx_VBUS_DETECT,

These terminals GND short or terminal OPEN, what events do you considered?

Increase in dark current and Terminal damage?

Why not go until TFT function stop?

Or TFT function stop?

2.  About the unused terminal of 10 k-pullup is DCU0_TCON6,

These terminals3.3v short or terminal OPEN, what events do you considered?

Increase in dark current and Terminal damage?

Why not go until TFT function stop?

Or TFT function stop?

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[richard_stulens]

Hi Takahashi-san,

USB_DCAP and  USBx_VBUS are the output and the input of the 3p0_LDO. This LDO supplies 3.0V to the USB PHY.

The input of the LDO is USBx_VBUS. USBx_VBUS_DETECT is an input to comparators in the PHY.

When the USB is not used (neither USB0 or USB1) then these terminals can be tied to GND over a 10K resistor to prevent them to float.

Optionally a capacitor on USB-DCAP can be installed and then the VBUS and VBUS_DETECT can be left floating.

The USB signals are not related to the DCU (TFT) module.

I do not understand the question about DCU_TCON6 there are no recommendations for this. The recommendations in the data sheet are for power supplies of analog modules. Analog modules consume power also when there is not clock.

DCU_TCON outputs are digital outputs. If they are not used they can still be configured as output and drive them low. They will nor consume power in this state an the output is low impedance which is good for ESD protection. Obviously you can put 10K resistor to GND as well if the customer prefers that.

Best regards,

Richard