NEC PD703114 User Manual page 591

<2> Reset timing
V (5 V)
DD
REGIN (3.3 V)
RESET (input)
Internal REGRES5 (5 V)
Undefined
Internal RES5 (5 V)
Undefined
Internal RES3 (3.3 V)
Undefined
Note The internal system reset signal stays active for at least 4 system clocks after the reset status caused by
the RESET pin is released.
<3> Description
A reset operation at power-on (power supply application) must guarantee "regulator output stabilization
time + oscillation stabilization time" from power-on until reset acknowledgment due to the low level width
of the RESET signal.
Cautions 1. The V850E/IA2 has an internal regulator that generates 3.3 V from a 5 V system
power supply. Therefore, 3.3 V system power is supplied after the lapse of the
regulator output stabilization time after 5 V power was supplied. When supplying
the two power supplies from external supplies with the regulator turned off, be sure
to supply 5 V system power first.
2. The V850E/IA2 is internally reset after 3.3 V system power has been supplied.
During the regulator output stabilization time, the internal circuits may not be reset
when only 5 V system power is being supplied. Consequently, the pins may output
undefined levels. For this reason, the V850E/IA2 makes the pins listed in (a) below
that may affect the application system (mainly the I/O pins of the internal timers) go
into a high-impedance state (refer to (b) and (c) below).
Note that pins other than those to be controlled do not go into a high-impedance
state unless supplied with 3.3 V system power.
The pins listed in (a) may also output undefined levels until a 5 V reset (internal
RES5) occurs (after the power was supplied until VDD reaches approximately 1.8 V
(reference value)) if the 5 V system power supply is gradually stabilized.
undefined level output time depends on how rapidly the power supply is stabilized.
Attention must be paid when the system requires several tens of ms for the 5 V
system power to stabilize.
CHAPTER 13 RESET FUNCTION
Active low
Active low
Active high
Active high
Regulator
Oscillation
output
stabilization time
stabilization
time
User's Manual U15195EJ5V0UD
Analog delay
Note
Reset release
The
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