DS2435 View Datasheet(PDF) - Dallas Semiconductor -> Maxim Integrated

Part Name

Description

Manufacturer

DS2435

Battery Identification Chip with Time/Temperature Histogram

Dallas Semiconductor -> Maxim Integrated 

DS2435

MEMORY

The DS2435’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 4 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,

time/temperature histogram registers, elapsed time counter, 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, the cycle count registers and the histogram

bin limits in E2 RAM, 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 (E2) RAM.

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 4. 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 (E2) RAM.

These 8 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, such as gas gauge and self-discharge

information. Should the battery go dead and power to the DS2435 is lost, this data may also be lost. Data

which must remain even if power to the DS2435 is lost should be placed in either Page 1 or Page 2.

PAGE 4

The fourth page of memory is used by the DS2435 to store the converted value of battery temperature, the

time/temperature histogram data, and the elapsed time counter. A 2-byte status register is also provided.

TEMPERATURE REGISTERS (60h-61h)

The DS2435 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 VDD specified. The first

register, at address 60h, provides ½°C resolution for temperatures between 0°C and 127 ½°C, formatted

as follows:

4 of 24

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