em78p5842 ELAN Microelectronics Corp, em78p5842 Datasheet - Page 37

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

POR reset voltage is influenced in process or temperature. For some application, a constant reset voltage is
important. Next circuit will support a adjust reset voltage. By adjusting R41 and R46, POR reset voltage will be a
constant (Vpor) and the potential on /RESET pin will drop to 0 when VDD drop to below Vpor. Next plot show
the relative between VDD and Vpor. When R41 = 3.9M ohm and R46 = 910K ohm, /RESET will keep to 0 if
VDD is below 2.24V and will active after VDD upper to 2.1V.
__________________________________________________________________________________________________________________________________________________________________
* This specification is subject to change without notice.
VDD
2.24V
910K
2.1V
3M9
R41
R46
VDD
Fig 17: The relative between VDD and Vpor
Fig 16: External power on reset circuit 2
22M
R44
2M2
C1815
R42
Q3
330K
C1815
R43
35
Q2
104
C31
S10
/RESET
VDD
RESET
RESET
T
EM785840/5841/5842
8-bit Micro-controller
2004/11/10 V1.2