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EM78P809N
8-Bit Microcontroller
current leakage from the /RESET pin is about ± 5 μ A, it is recommended that R should
not be greater than 40K. In this way, the /RESET pin voltage is held below 0.2V. The
diode (D) acts as a short circuit at the moment of power down. The capacitor C will
discharge rapidly and fully. Rin, the current-limited resistor, will prevent high current or
ESD (electrostatic discharge) from flowing to pin /RESET.
EM78P809N
4.18.2 Residue-Voltage Protection
When battery is replaced, device power (V
The residue-voltage may trip below V
cause a poor power-on reset. Fig.35 and Fig.36 show how to build the residue-voltage
protection circuit.
60 •
Vdd
/RESET
Fig. 35. External Power-Up Reset Circuit
Vdd
EM78P809N
Q1
/RESET
40K
Fig. 36. Residue Voltage Protection Circuit 1
R
Rin
C
) is taken off but residue-voltage remains.
DD
minimum, but not to zero. This condition may
DD
33K
10K
1N4684
Product Specification (V1.0) 07.26.2005
(This specification is subject to change without further notice)
D
Vdd
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