Renesas Technology, Tools FAQs
Last Updated: July 5, 2000
Document Number: 01051025_e
Q.
Is the power supply (VDD) to the emulator MCU in the M37902T-RPD-E pod only supplied from the ICE system? How is the
power supply (VCC) from the target configured in the pod? When there is electric potential difference in the power supplied to the
pod and the target power supply, what happens to the I/O port output, etc.?
A.
The supply (VDD) of the emulator MCU is first connected to the jumper switch in the following configurations.
5V : 5.0 ± 0.1V is supplied regardless of the target supply system.
3.3V : 3.3 ± 0.1V is supplied regardless of the target supply system.
SENSE: voltage difference ± 0.1V is supplied from the ICE by sensing the target system supply voltage. If there is no target
connected or the supply of the target is more than 5V, the ICE supplies 5V power to the MCU automatically.
In any situation, the power is always generated and supplied by the ICE yet still monitors the target voltage supply. If there is a
miss-matched switch setting or a slight voltage difference between the ICE and the target, a leaking current will continually flow
from all pins of the emulation MCU at the 5V/3.3V setting.
When using a 5.0V MCU, to lesson the difference with the target supply voltage (ex. 4.5V), please set the jumper switch to the
"SENSE" position, which will minimize any leaking current problem.
When you use the 3.3V version MCU, if you set the switch to the "SENSE" position without connection to target, 5V power will be
supplied to the MCU, which may damage the MCU.
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