The TVccd signal on the NETIMPRESS is not a terminal for supplying power
to the target board, but rather an input terminal with the following two main roles:
1. It monitors whether power is being supplied to the target board.
(If the voltage falls below the threshold voltage, a TVCC TOO LOW error will occur.)
* Confirm that power is being supplied to the target at the start of programming.
* Confirm that the target power supply voltage does not drop during programming.
2. Adjustment of the signal input/output interface voltage with the target.
* The voltage level input to the TVccd (e.g., 3.3V or 5V) becomes the signal
input/output interface voltage with the target.
* Generation of power supply for the I/F buffer IC.
Based on the voltage input to the TVccd, the operational amplifier
on the NETIMPRESS probe hardware (such as PHX400) performs current
amplification, which is then used as the power supply for the output stage
buffer IC.
This configuration is designed to prevent large currents from being drawn
from the target side.
The current consumption of a TVccd is almost zero due to the high input
impedance of the circuit, maximum 300uA (0.3mA). (As stated in the
DC characteristics specifications for PHX400, PHX401, and PHX403)