DS2438Z データシートの表示（PDF） - Dallas Semiconductor -> Maxim Integrated
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DS2438Z Datasheet PDF : 29 Pages
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THRESHOLD REGISTER FORMAT Table 6
TH2
TH2 TH1 0 0 0 0 0 0
MSb
LSb
TH1
0
0
0
1
1
0
1
1
DS2438
THRESHOLD
None (default)
±2 LSB
±4 LSB
±8 LSB
The Charging Current Accumulator (CCA) is a two-byte nonvolatile read/write counter which represents
the total charging current the battery has encountered in its lifetime. It is only updated when current
through RSENS, is positive; i.e., when the battery is being charged. Similarly, the Discharge Current
Accumulator (DCA) is a two-byte nonvolatile counter which represents the total discharging current the
battery has encountered over its lifetime.
The CCA and DCA can be configured to function in any of three modes: disabled, enabled with shadow-
to-EEPROM, and enabled without shadow-to-EEPROM. When the CCA and DCA are disabled (by
setting either the IAD bit or the CA bit in the Status/Configuration Register to “0”), the memory in page
07h is free for general purpose data storage. When the CCA and DCA are enabled (by setting both IAD
and CA to “1”), page 07h is reserved for these registers, and none of the bytes in page 07h should be
written to via the 1-Wire bus. When the CCA and DCA are enabled, their values are automatically
shadowed to EEPROM memory by setting the EE bit in the Status/Configuration Register to “1”. When
these registers are configured to shadow to EEPROM, the information will accumulate over the lifetime
of the battery pack and will not be lost when the battery becomes discharged. Shadow-to-EEPROM is
disabled when the EE bit is “0”. Table 7 illustrates the format of the CCA and DCA registers. Table 8
summarizes the modes of operation for ICA, CCA and DCA.
CCA/DCA REGISTER FORMAT Table 7
27
26
25 24
23
22
21
20 LSB
MSb
(unit = 15.625 mVHr) LSb
215 214 213 212 211 210 29 28 MSB
ICA/CCA/DCA MODES OF OPERATION Table 8
IAD Bit
CA Bit
EE Bit
ICA
CCA/DCA
0
X
X
Inactive
Inactive
1
0
X
Active
Inactive
1
1
0
Active
Active
1
1
1
Active
Active
CCA/DCA Copy-
to-EEPROM
Inactive
Inactive
Inactive
Active
8 of 29
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