8-Bit Microcontroller with OTP ROM Specification Sheet

EM78P447N
8-Bit Microcontroller with OTP ROM
Product Specification (V1.1) 03.30.2005
• 29
(This specification is subject to change without further notice)
4.11 Residue-Voltage Protection
When battery is replaced, device power (Vdd) is taken off but residue-voltage remains.
The residue-voltage may trips below Vdd minimum, but not to zero. This condition may
cause a poor power on reset. Fig.16 and Fig.17 show how to build the residue-voltage
protection circuit.
EM78P447N
/RESET
Vdd
40K
Q1
1N4684
10K
33K
Vdd
Fig. 14 The Residue Voltage Protection Circuit 1
EM78P447N
/RESET
Vdd
Q1
Vdd
40K
R2
R1
Fig. 15 The Residue Voltage Protection Circuit 2