Appendix E Usage Notes; Power Supply Rise And Fall Order - Renesas Hitachi H8S/2194 Series Hardware Manual

E.1

Power Supply Rise and Fall Order

Figure E.1 shows the order in which the power supply pins rise when the chip is powered on, and
the order in which they fall when the chip is powered down. If the power supply voltages cannot
rise and fall simultaneously, power supply operations should be carried out in this order.
At power-on, wait until the microcomputer section power supply (V
prescribed voltage, then raise the other analog power supplies.
At power-down, drop the analog power supplies first, followed by the microcomputer section
power supply (V ).
CC
When powering up and down, ensure that the voltage applied to the pins does not exceed the
respective power supply voltage.
V , AV
CC CC
SV
CC
V : Microcomputer section power supply voltage
CC
AV : A/D converter power supply voltage
CC
SV : Servo section power supply voltage
CC
Vin : Pin applied voltage
In power-down modes (except sleep mode), the analog power supplies can be turned off to
reduce current dissipation. When the microcomputer section power supply (V
the backup voltage in a power-down mode, the order shown in figure E.2 should be followed.
Make sure that the voltage applied to the pins does not exceed the respective power supply
voltage.
The A/D converter power supply (AV
microcomputer section power supply (V
is turned off inside the device. At this time, the AV

Appendix E Usage Notes

Vin
Figure E.1 Power Supply Rise and Fall Order
) should be set to the same potential as the
CC
). In all power-down modes except sleep mode, AV
CC
) has risen to the
CC
Vin
current dissipation is defined as AISTOP.
CC
Rev. 2.0, 11/00, page 1033 of 1037
V , AV
CC CC
SV
CC
) is dropped to
CC
CC