RX8804CE
Page - 31
ETM59E-05
8.8. Temperature Compensation Function
8.8.1. Temperature Compensation Function
During the production process of the RTC, we are programming the individual characteristics of the built-in crystal
into the non-volatile memory of the RTC. The build-in temperature sensor measures the actual temperature of the
module and compensates the oscillation frequency of the crystal oscillator using the stored compensation data. This
way not only the time information is temperature compensated, but as well the FOUT signal, even when outputting
32.768 kHz. This function works in the supply voltage range VTEM.
8.8.2. Related Registers for Temperature Compensation Function
Table 56 Temperature Compensation Register
Address
Function
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
0F
Control 2
CSEL1
CSEL0
UIE
TIE
AIE
RESET
1) CSEL1, CSEL0 (Compensation Interval Select 1, 0) bit
This bit sets an interval of a temperature compensation operation.
Current consumption decreases when increasing the Compensation Interval by means CSEL1, 0. CSEL1, 0 is set
at the time of initial power-up to (
“0”, “1”).
Table 57 CSEL bit
CSEL0,1
CSEL1
CSEL0
Compensation interval
Write / Read
0
0
0.5 s
0
1
2.0 s
Default
1
0
10 s
1
1
30 s
Even if the power supply voltage falls below V
TEM
and a VDET bit is set to
“1”, the temperature compensation operation is
performed again if the supply voltage raises above V
TEM
.