em78p809n ELAN Microelectronics Corp, em78p809n Datasheet - Page 64

• Manufacturer Part Number: em78p809n
• Description: 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

EM78P809N
8-Bit Microcontroller
60 •
4.18.2 Residue-Voltage Protection
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.
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.
EM78P809N
/RESET
EM78P809N
Vdd
Fig. 35. External Power-Up Reset Circuit
/RESET
Vdd
Fig. 36. Residue Voltage Protection Circuit 1
40K
Q1
Rin
(This specification is subject to change without further notice)
DD
minimum, but not to zero. This condition may
DD
R
C
) is taken off but residue-voltage remains.
Product Specification (V1.0) 07.26.2005
1N4684
10K
33K
D
Vdd