DS2437S Maxim Integrated Products, DS2437S Datasheet - Page 14

• Manufacturer Part Number: DS2437S
• Description: IC MONITOR SMART BATTERY 16-SSOP
• Manufacturer: Maxim Integrated Products

Specifications of DS2437S

• Function: Battery Monitor
• Battery Type: Smart Batteries
• Voltage - Supply: 2.7 V ~ 10 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

DS2437
MEMORY MAP
The DS2437’s memory is organized as shown in Figure 7. The memory consists of a scratchpad RAM
and storage SRAM/EEPROM. The scratchpad helps 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 appropriate page in memory (pages 0-2
are primarily volatile SRAM, pages 3-7 are EEPROM). This process insures data integrity when
modifying the memory.
The DS2437’s memory is organized as 64 bytes of memory in eight 8-byte pages. Each page has its own
th
scratchpad space, organized as 8 bytes of memory. When reading a scratchpad, there is a 9
byte which
may be read with a Read Scratchpad command. This byte contains a cyclic redundancy check (CRC)
byte, which is the CRC over all of the 8 bytes in the currently selected scratchpad. This CRC is
implemented in the fashion described in the section titled “CRC Generation.”
Page 0 (00h)
The first page contains the most frequently accessed information of the DS2437, and most locations are
volatile read-only bytes with the exception of the Status / Configuration Register (Byte 0).
The Status / Configuration Register is a nonvolatile read/write byte which defines which features of the
DS2437 are enabled and how they will function. The register is formatted as follows:
IAD = Current A/D Control Bit. 1 = the current A/D and the ICA are enabled, and current measurements
will be taken at the rate of 32 Hz; 0 = the current A/D and the ICA have been disabled.
CA = Current Accumulator Configuration. 1 = CCA/DCA are enabled, and data will be stored and can be
retrieved from page 7, bytes 4-7; 0 = CCA/DCA is disabled, and page 7 can be used for general
EEPROM storage.
E2? = Current Accumulator Shadow Selector bit. 1 = CCA/DCA counter data will be shadowed to
EEPROM each time the respective register is incremented by 0.32C; 0 = CCA/DCA counter data will not
be shadowed to EEPROM. The CCA/DCA could be lost as the battery pack becomes discharged. If the
CA bit in the status/configuration register is set to 0, the E2? bit will have no effect on the DS2437
functionality.
AD = Voltage A/D Input Select Bit. 1 = the battery input (VDD) is selected as the input for the DS2437
voltage A/D converter; 0 = the general purpose A/D input (VAD) is selected as the voltage A/D input.
For either setting, a Convert V command will initialize a voltage A/D conversion.
TB = Temperature Busy Flag. 1 = temperature conversion in progress; 0 = temperature conversion
complete.
NVB = Nonvolatile Memory Busy Flag. 1 = Copy from Scratchpad to EEPROM in progress; 0 =
Nonvolatile memory not busy. A copy to EEPROM may take from 2 ms to 10 ms (taking longer at lower
supply voltages).
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