R01UH0823EJ0100 Rev.1.00
Page 249 of 1823
Jul 31, 2019
RX23W Group
12. Battery Backup Function
12.
Battery Backup Function
12.1
Overview
When the voltage at the VCC pin is dropped, power can be supplied to the realtime clock (RTC) and the sub-clock
oscillator placed in the battery backup power area from the battery backup power pin (VBATT pin).
When the battery backup function is not used, connect the VBATT pin to the VCC pin and disable the battery backup
function (set the VBATTCR.VBATTDIS bit to 1).
The VBATT pin voltage level and battery backup power voltage drop detection can be confirmed by reading the VBATT
status register.
shows the configuration of the battery backup function.
Figure 12.1
Configuration of Battery Backup Function
Sub-clock
oscil
lat
or
XCIN
XCOUT
RTCIC0,
RTCIC1 pin
VCC
VBATT
Battery backup power area
Switch
control
VBATT pin voltage monitor flag
(VBATTSR.VBTLVDMON)
RTC
Battery backup power voltage drop
detection flag
(VBATTSR.VBATRLVDETF)
Internal
reference
voltage
(Vdetvbt
detection)
+
-
Vdetvbt
Internal
reference
voltage
(VDETBATT
detection)
+
-
VDETBATT
0
1
Voltage drop
detection
circuit
< 1.8 V
Voltage
regulator for
backup power
area