EM78P259N/260N
8-Bit Microprocessor with OTP ROM
6.12.3 Residual Voltage Protection
When the battery is replaced, device power (Vdd) is removed but the residual voltage
remains. The residual voltage may trip below Vdd minimum, but not to zero. This
condition may cause a poor power-on reset. Fig. 6-21 and Fig. 6-22 show how to
create a protection circuit against residual voltage.
Vdd
Vdd
EM78P259N
EM78P260N
33K
Q1
10K
/RESET
100K
1N4684
Fig. 6-21 Residual Voltage Protection Circuit 1
Vdd
Vdd
R1
EM78P259N
EM78P260N
Q1
R3
/RESET
R2
Fig. 6-22 Residual Voltage Protection Circuit 2
66 •
Product Specification (V1.0) 06.16.2005
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
