DS2751
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TEMPERATURE MEASUREMENT
The DS2751 uses an integrated temperature sensor to continually measure battery temperature.
Temperature measurements are updated in the Temperature Register every 220ms in two’s-complement
format with a resolution of 0.125°C over a ±127°C range. The Temperature Register format is shown in
Figure 7.
Figure 7. TEMPERATURE REGISTER FORMAT
MSB—Address 18 LSB—Address 19
S 2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
X X X X X
MSb LSb MSb LSb
Units: 0.125°C
PROGRAMMABLE I/O
To use the PIO pin as an output, write the desired output value to the PIO bit in the Special Feature
Register. Writing a 0 to the PIO bit enables the PIO output driver, pulling the PIO pin to V
SS
. Writing a 1
to the PIO bit disables the output driver, allowing the PIO pin to be pulled high or used as an input. To
sense the value on the PIO pin, read the PIO bit. The DS2751 turns off the PIO output driver and sets the
PIO bit high when in sleep mode or when DQ is low for more than t
SLEEP
(2.2s), regardless of the state of
the PMOD bit.
MEMORY
The DS2751 has a 256-byte linear address space with registers for instrumentation, status, and control in
the lower 32 bytes, with lockable EEPROM and SRAM memory occupying portions of the remaining
address space. All EEPROM and SRAM memory is general-purpose except addresses 31h and 33h,
which should be written with the default values for the Status Register and Current Offset Register,
respectively. When the MSB of any two-byte register is read, both the MSB and LSB are latched and held
for the duration of the Read Data command to prevent updates during the read and to ensure
synchronization between the two register bytes. For consistent results, always read the MSB and the LSB
of a two-byte register during the same Read Data command sequence.
EEPROM memory is shadowed by RAM to eliminate programming delays between writes and to allow
the data to be verified by the host system before being copied to EEPROM. All reads and writes to/from
EEPROM memory actually access the shadow RAM. In unlocked EEPROM blocks, the Write Data
command updates shadow RAM. In locked EEPROM blocks, the Write Data command is ignored. The
Copy Data command copies the contents of shadow RAM to EEPROM in an unlocked block of
EEPROM but has no effect on locked blocks. The Recall Data command copies the contents of a block of
EEPROM to shadow RAM regardless of whether the block is locked or not.
