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[v1-10] 2018-Apr-25

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AS39513 − Detailed Description

Battery Check

Before executing any measurement it is possible to check the

status of the battery by performing the so called Battery Check.

It is executed if the System parameter BATCHK is set to 1, then

a coarse battery check is enabled. The reason of performing this

check is that the power-on-reset only ensures that the battery

voltage is enough for the logic to function but it does not

guarantee that the battery voltage is within the tolerances for

accurate measurements.

The battery check involves the following steps. First, the battery

check sensor elements are enabled. There is a brief wait for the

analog circuits to settle. Using the battery type determined

during RESET mode, the battery check comparator output will

indicate if the battery voltage is acceptable. If it is, then the rest

of the logging continues, if it is not, the logging stops, and the

error flag, present in the System parameter, LOWBAT is set. Note

that if a logging event was skipped because of low battery, the

measurement counter is still incremented to give some

indication of how many measurements were skipped. Because

the battery may be too weak for a reliable write, the

measurement counter will not be written to EEPROM if the

battery voltage check has failed.

Figure 10:

Battery Check Threshold Voltages

Battery Type

BCKSEL [1:0]

Threshold Voltage (V)

1.5V

1.2

2.2

2.1

2.0

1.9

AS39513 데이터시트(PDF) 19 Page - ams AG