Rev. 2.00, 09/03, page 624 of 690
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Power-off order
1. In the reverse order of powering-on, first turn off the 1.5 V power, then turn off the 3.3 V
power within 1 ms. It is recommended that this interval will be as short as possible.
2. Pin states are undefined while only the 1.5 V power is off. The system design must ensure
that these undefined states do not cause erroneous system operation.
3. When the power is turned off, make sure that the voltage of the 1.5 V power is lower than
that of the 3.3 V power.
Waveforms and recommended times at power on/off are shown in figure 25.1.
tpwu
VccQ: 3.3 V power
VccQ (min) voltage
VccQ (min)
attain time
Vcc (min)
attain time
Vcc: 1.5 V power
Vcc (min) voltage
Vcc/2 level voltage
Normal operation term
States undefined
term
Operation stopped
Clock oscillation started
Oscillation settling time
Cancel the power-on reset and
go to normal operation
tunc
GND
tpwd
Figure 25.1 Power On/Off Sequence
Recommended Power On/Off Times
Item
Symbol
Max. Permitted
Value
Unit
VccQ to Vcc power-on time interval
tpwu
1
ms
VccQ to Vcc power-off time interval
tpwd
1
ms
State undefined term
tunc
10
ms
The recommended times shown above do not require strict settings.
The state undefined term indicates that pins are at the power rising stage. The pin state is stabilized
at VccQ (min) attain time. However, a power-on reset (
RESETP) is accepted successfully only
after VccQ (min) attain time and clock oscillation settling time. Set the state undefined term less
than 10 ms.
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