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H330S Hardware User Manual
Page 26 of 44
5.1.4 VRTC
VRTC is the power supply of the RTC inside the module, and it can be used as the backup power signal
as well.
Minimum Value
Recommended Value
Unit
1.71
1.8
1.89
V
VRTC input voltage
(RTC is in normal)
0.5
1.8
1.89
V
VRTC input current
(RTC is in normal)
1.0
uA
The reference design of VRTC circuit is as follows:
Figure 5- 1 VRTC Reference Design
Note:
R8 is a current-limiting resistor, used to ensure the VRTC module works properly, free from
being affected by peripheral circuits. R8≥1k ohm
VRTC power consumption current<1uA
The value of C9 will affect the retaining time of RTC after VBAT powers off. The retaining
time of RTC can be roughly calculated by the following formula:
T= (1.8-0.5)*C/1=1.3C, unit: second. Namely, if the value of C9 is 100uF, the retaining time of
RTC will be around 130s.
