SN8P2740 Series
ADC, OP-amp, Comparator 8-Bit Micro-Controller
The LVD (low voltage detector) is built-in Sonix 8-bit MCU to be brown out reset protection. When the VDD drops and
is below LVD detect voltage, the LVD would be triggered, and the system is reset. The LVD detect level is different by
each MCU. The LVD voltage level is a point of voltage and not easy to cover all dead-band range. Using LVD to
improve brown out reset is depend on application requirement and environment. If the power variation is very deep,
violent and trigger the LVD, the LVD can be the protection. If the power variation can touch the LVD detect level and
make system work error, the LVD can‟t be the protection and need to other reset methods. More detail LVD information
is in the electrical characteristic section.
The LVD is three levels design (2.0V/2.4V/3.6V) and controlled by LVD code option. The 2.0V LVD is always enable for
power on reset and Brown Out reset. The 2.4V LVD includes LVD reset function and flag function to indicate VDD
status function. The 3.6V includes flag function to indicate VDD status. LVD flag function can be an easy low battery
detector. LVD24, LVD36 flags indicate VDD voltage level. For low battery detect application, only checking LVD24,
LVD36 status to be battery status. This is a cheap and easy solution.
086H
PFLAG
Read/Write
After reset
Bit 7
NT0
R/W
-
Bit 6
NPD
R/W
-
Bit 5
LVD36
R
Bit 4
LVD24
R
Bit 3
Bit 2
C
R/W
0
Bit 1
DC
R/W
0
Bit 0
Z
R/W
0
-
-
-
0
0
Bit 5
Bit 4
LVD36: LVD 3.6V operating flag and only support LVD code option is LVD_H.
0 = Inactive (VDD > 3.6V).
1 = Active (VDD ≦ 3.6V).
LVD24: LVD 2.4V operating flag and only support LVD code option is LVD_M.
0 = Inactive (VDD > 2.4V).
1 = Active (VDD ≦ 2.4V).
LVD Code Option
LVD
LVD_L
LVD_M
LVD_H
Available
-
LVD_MAX
Available
2.0V Reset
2.4V Flag
2.4V Reset
3.6V Flag
3.6V Reset
Available
Available
Available
-
-
-
-
-
-
-
-
-
-
Available
Available
-
Available
LVD_L
If VDD < 2.0V, system will be reset.
Disable LVD24 and LVD36 bit of PFLAG register.
LVD_M
If VDD < 2.0V, system will be reset.
Enable LVD24 bit of PFLAG register. If VDD > 2.4V, LVD24 is “0”. If VDD ≦2.4V, LVD24 flag is “1”.
Disable LVD36 bit of PFLAG register.
LVD_H
If VDD < 2.4V, system will be reset.
Enable LVD24 bit of PFLAG register. If VDD > 2.4V, LVD24 is “0”. If VDD ≦2.4V, LVD24 flag is “1”.
Enable LVD36 bit of PFLAG register. If VDD > 3.6V, LVD36 is “0”. If VDD ≦3.6V, LVD36 flag is “1”.
LVD_MAX
If VDD < 3.6V, system will be reset.
Note:
1. After any LVD reset, LVD24, LVD36 flags are cleared.
2. The voltage level of LVD 2.4V or 3.6V is for design reference only. Don’t use the LVD indicator as
precision VDD measurement.
SONiX TECHNOLOGY CO., LTD
Page 39
Version 2.0
SONIX [ SONIX TECHNOLOGY COMPANY ]
