Power-On Sequence When Using Ram Backup - Renesas M32R/ECU Series User Manual

20

20.2.2 Power-On Sequence when Using RAM Backup

The diagram below shows a turn-on sequence of the power supply (5.0 V or 3.3 V) when using RAM backup.
VCCE,
VCC-BUS,
OSC-VCC 0V
AVCC
0V
0V
VREF
RESET#
0V
3.0V
VDDE
0V
Note 1: After turning on all power supplies and holding the RESET# pin low for an oscillation stabilization time,
release the RESET# pin back high (to deassert the reset input).
Note 2: Because of RAM backup, it is assumed that VDDE is 3.0 V or more. The diagram here is shown for the VCCE = 5 V case.
Notes: • Power-on limitations
VCCE = OCS-VCC
VDDE ≥ VCCE, OSC-VCC
• However, if the above power-on limitations cannot be met, sufficient evaluation must be made during system design
in order to ensure that no power will be applied to the microcomputer with a potential difference of 1 V or more.
For potential differences 0 V to 0.6 V, there is almost no in-flow current. The amount of in-flow current begins to increase
when the potential difference exceeds 0.6 V.
Figure 20.2.2 Power-On Sequence when Using RAM Backup
If VDDE is 3.0 V or more, there will be no problem even when
the limitations VDDE ≥ VCCE, OSC-VCC cannot be met.
(Note 1)
(Note 2)
20-4
POWER SUPPLY CIRCUIT
20.2 Power-On Sequence
32180 Group User's Manual (Rev.1.0)