DS2434 Dallas Semiconducotr, DS2434 Datasheet - Page 6

• Manufacturer Part Number: DS2434
• Description: Battery Identification Chip
• Manufacturer: Dallas Semiconducotr

MEMORY
The DS2434’s memory is divided into five pages, each page filling 32 bytes of address space. Not all of
the available addresses are used, however. Refer to the memory map of Figure 3 to see actual addresses
which are available for use.
The first three pages of memory consist of a scratchpad RAM and then either a nonvolatile RAM (pages 1
and 2) or SRAM (page 3). The scratchpads help insure data integrity when communicating over the 1-
Wire bus. Data is first written to the scratchpad where it can be read back. After the data has been
verified, a Copy Scratchpad command will transfer the data to the RAM (NV or SRAM). This process
insures data integrity when modifying the memory.
The fourth page of memory consists of registers which contain the measured temperature value and status
registers for the device; these registers are made from SRAM cells.
The fifth page of memory holds the ID number for the device and the cycle count registers in E
making these registers nonvolatile under all power conditions.
PAGE 1
The first page of memory has 24 bytes. It consists of a scratchpad RAM and a nonvolatile (E
These 24 bytes may be used to store any data the user wishes; such as battery chemistry descriptors,
manufacturing lot codes, gas gauge information, etc.
The nonvolatile portion of this page may be locked to prevent data stored here from being changed
inadvertently.
Both the nonvolatile and the scratchpad portions are organized identically, as shown in the memory map
of Figure 3. In this page, these two portions are referred to as NV1 and SP1, respectively.
PAGE 2
The second page of memory has 8 bytes. It consists of a scratchpad RAM and a nonvolatile (E
These eight bytes may be used to store any data the user wishes, such as battery chemistry descriptors,
manufacturing lot codes, gas gauge information, etc.
PAGE 3
The third page of memory has a full 32 bytes. It consists of a scratchpad RAM and an SRAM. This
address space may be used to store any data the user wishes, provided that, should the battery go dead and
power to the DS2434 is lost, this data may also be lost without serious repercussions. Data which must
remain even if power to the DS2434 is lost should be placed in either Page 1 or Page 2.
This section of memory may be used to store gas gauge and self-discharge information. If the battery dies
and this information is lost, it is moot because the user can easily determine that the battery is dead.
PAGE 4
The fourth page of memory is used by the DS2434 to store the converted value of battery temperature. A
2-byte status register is also provided.
TEMPERATURE REGISTERS (60h-61h)
The DS2434 can measure temperature without external components. The resulting temperature
measurement is placed into two temperature registers. These registers are SRAM, and therefore will hold
the values placed in them until the battery voltage falls below the minimum V
6 of 20
DD
specified. The first
2
2
2
) RAM.
) RAM.
DS2434
RAM,