EM78P312N
8-Bit Microcontroller
Vdd
/RESET
R
C
D
EEMM7788PP381029NN
Rin
Fig. 5-34 External Power-Up Reset Circuit
5.18.2 Residue-Voltage Protection
When battery is replaced, device power (VDD) is taken off but residue-voltage remains.
The residue-voltage may trip below VDD minimum, but not to zero. This condition may
cause a poor power-on reset. Fig.35 and Fig. 36 show how to build the residue-voltage
protection circuit.
Vdd
Vdd
33K
EM78P312N
EM78P809N
Q1
10K
/RESET
40K
1N4684
Fig. 5-35 Residue Voltage Protection Circuit 1
Vdd
Vdd
R1
EM78P312N
EM78P809N
Q1
/RESET
R2
40K
Fig. 5-36 Residue Voltage Protection Circuit 2
Product Specification (V1.0) 10.03.2006
(This specification is subject to change without further notice)
• 55
ELAN [ ELAN MICROELECTRONICS CORP ]
