R01UH0823EJ0100 Rev.1.00
Page 254 of 1823
Jul 31, 2019
RX23W Group
12. Battery Backup Function
Figure 12.3
Operation Example of the VBATT Pin Power Voltage Monitor Flag
Figure 12.4
Operation Example of the Battery Backup Power Voltage Drop Detection Flag
12.3.2
VBATT Pin Voltage Monitoring Function
When the VCC is supplied, the VBATT pin voltage can be monitored. This function is disabled after a reset.
After the VBATT pin voltage drop detection enable bit (VBATTCR.VBTLVDEN) is set to 1, the VBATT pin voltage
level can be monitored by reading the VBATT pin voltage monitor flag (VBATTSR.VBTLVDMON).
VCC pin voltage
VBATT pin voltage
VBATT
operating range
Vdetvbt
VBATT pin voltage
monitor flag
1
0
VBATT pin voltage drop
detected
VBATT pin voltage < Vdetvbt
VBATT pin voltage rise
detected
VBATT pin voltage
Vdetvbt
VBATT pin voltage
Vdetvbt
VBATT
VCC
VDETBATT
VCC pin voltage
VBATT pin voltage
VBATT
operating
range
Battery backup power
voltage drop detection
flag
CPU writes 0 to the battery backup
power voltage drop detection flag
Undefined
1
0
VDETBATT
VCC
Power supply from
VCC pin
Power supply from VBATT pin
Power supply from
VCC pin
VBATT operating
voltage drop detected
VBATT operating
voltage rise detected
Outside the VBATT
operating range