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Is there trouble if two kinds of power are turn on/off simultaneously?

Latest Updated:03/24/2009

Question:

The hardware manual states as follows in "Caution" of the absolute maximum rating:"When powering on, First turn on the 3.3V power. And when powering off, in the reverse order of powering-on, first turn off the 1.7V/ 1.8V/ 1.9V/ 2.0V power."
1. Are there no problems if two kinds of powers are turned on/off simultaneously?
2. What problem occur when the order of powering on/off is not followed?

Answer:

If two kinds of power supply voltage satisfy the following formula, there is no problem.

Voltage of 1.5V/1.7V/1.8V/1.9V/2.0V power ≤ Voltage of 3.3V power

Power ON interval of 3.3V power and 1.5V/1.7V/1.8V/1.9V/2.0V power is recommended to be within 1ms but please note that this is reference value. The pin states remain undefined untill all power is supplied and a high level is input at the CA pin and a low level at the /RESETpin.The system design must ensure that these undefined states do not cause erroneous system operation.

Suitable Products
SH7700 Series
SH7729R
SH7727
SH7720
SH7709S
SH7706
SH7705