em78p134n ELAN Microelectronics Corp, em78p134n Datasheet - Page 51

• Manufacturer Part Number: em78p134n
• Description: 8-bit Microcontroller With Otp Rom
• Manufacturer: ELAN Microelectronics Corp

Product Specification (V1.6) 06.02.2010
(This specification is subject to change without further notice)
5.11.2 Residual Voltage Protection
When the battery is replaced, device power (Vdd) is removed but residual voltage
remains. The residual voltage may trip below Vdd minimum, but not to zero. This
condition may cause a poor power-on reset. Figure 5-21 and Figure 5-22 show how to
create a protection circuit against residual voltage.
5.12 Code Option Register
The EM78P134N has Code Option words that are not part of the normal program
memory. The option bits cannot be accessed during normal program execution.
Code Option Register and Customer ID Register arrangement distribution:
Bit 12~Bit 0
Word 0
Figure 5-21 Residual Voltage Protection Circuit 1
Figure 5-22 Residual Voltage Protection Circuit 2
/RESET
/RESET
VDD
VDD
100K
Q1
Q1
R3
Bit 12~Bit 0
Word 1
8-Bit Microcontroller with OTP ROM
10K
1N4684
33K
R1
R2
VDD
VDD
Bit 12~Bit 0
Word 2
EM78P134N
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