em78p5842 ELAN Microelectronics Corp, em78p5842 Datasheet - Page 36

• Manufacturer Part Number: em78p5842
• Description: 8-bit Micro-controller
• Manufacturer: ELAN Microelectronics Corp

VII.12 Power on Considerations
its steady states. EM785840 power on reset voltage range is 1.6V ~ 2.0V. Under customer application, VDD must
drop to below 1.6V and remains OFF for 10uS before power can be switched on again. This way, EM785840 will
reset and work normally. The extra external reset circuit will work well if VDD can rise at very fast speed (50mS
or less). However, under most cases where critical applications are involved, extra devices are required to assist in
solving the power-up problems.
VII.13 External Power on Reset circuit
pulse. The pulse width should be kept long enough for VDD to reach minimum operation voltage. The diode D
acts as a short circuit at the moment of power down. The capacitor C will discharged rapidly and fully.
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* This specification is subject to change without notice.
By Setting code option “P71S” to 1, /RESET pin is selected. Next figure is an external RC to produce the reset
Any micro-controller is not guaranteed to start to operate properly before the power supply stabilizes at
Fig 15: The relative of IRC and ERIC mode’s normal and sleep mode
operation
RESET
Fig 15: External power on reset circuit 1
/RESET
VDD
Reset
Reset
R
C
34
D
ERC or IRC2 : ON
ERC or IRC2 : ON
IRC1 : ON
PLL : turn off
IRC1 : ON
PLL : turn off
(CPU stop)
Normal
Mode
Sleep
Mode
run"SLEP"
EM785840/5841/5842
8-bit Micro-controller
2004/11/10 V1.2