m48t201v STMicroelectronics, m48t201v Datasheet - Page 23

• Manufacturer Part Number: m48t201v
• Description: 5.0 Or 3.3v Timekeeper Supervisor
• Manufacturer: STMicroelectronics

Figure 10. Crystal accuracy across temperature
Figure 11. Calibration waveform
3.11
Frequency (ppm)
NORMAL
POSITIVE
CALIBRATION
NEGATIVE
CALIBRATION
–100
–120
–140
–160
–20
–40
–60
–80
Battery low warning
The M48T201Y/V automatically performs battery voltage monitoring upon power-up and at
factory-programmed time intervals of approximately 24 hours. The Battery Low (BL) Bit, Bit
D4 of Flags Register 7FFF0h, will be asserted if the battery voltage is found to be less than
approximately 2.5V. The BL Bit will remain asserted until completion of battery replacement
and subsequent battery low monitoring tests, either during the next power-up sequence or
the next scheduled 24-hour interval.
If a battery low is generated during a power-up sequence, this indicates that the battery is
below approximately 2.5V and may not be able to maintain data integrity in the SRAM. Data
should be considered suspect and verified as correct. A fresh battery should be installed.
20
0
–40
–30
–20
–10
0
10
Temperature C
F
F = -0.038
20
T
30
0
ppm
= 25 C
C
2
(T - T
40
0
)
2
50
10%
60
70
80
AI00999
AI00594B
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