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EM78P259N/260N
8-Bit Microprocessor with OTP ROM
66 •
Product Specification (V1.2) 05.18.2007
(This specification is subject to change without further notice)
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. 6-22 and Fig. 6-23 show how to
create a protection circuit against residual voltage.
EM78P259N
EM78P260N
/RESET
Vdd
100K
Q1
1N4684
10K
33K
Vdd
Fig. 6-22 Residual Voltage Protection Circuit 1
/RESET
Vdd
Q1
Vdd
R3
R2
R1
EM78P259N
EM78P260N
Fig. 6-23 Residual Voltage Protection Circuit 2