ds2437 Maxim Integrated Products, Inc., ds2437 Datasheet - Page 2

• Manufacturer Part Number: ds2437
• Description: Smart Battery Monitor
• Manufacturer: Maxim Integrated Products, Inc.

Applications for the smart battery pack monitor include portable computers, portable/cellular telephones,
and handheld instrumentation battery packs in which it is critical to monitor real-time battery
performance. Used in conjunction with a microcontroller in the battery pack or host system, the DS2437
provides a complete smart battery pack solution that is fully chemistry-independent. The customization
for a particular battery chemistry and capacity is realized in the code programmed into the
microcontroller and DS2437 EEPROM, and only a software revision is necessary should a designer wish
to change battery pack chemistry.
DETAILED PIN DESCRIPTION
OVERVIEW
The block diagram of Figure 1 shows the seven major components of the DS2437:
1. 64-bit lasered ROM
2. temperature sensor
3. battery voltage A/D
4. battery current A/D
5. current accumulators
6. real-time clock
7. 40-byte nonvolatile user memory
Each DS2437 contains a unique 64-bit lasered ROM serial number so that several battery packs can be
charged/monitored by the same host system. Furthermore, other Dallas products featuring the same
1-Wire bus architecture with a 64-bit ROM can reside on the same bus; refer to the Dallas "Automatic
Identification Data Book" for the specifications of these products.
Communication to the DS2437 is via a 1-Wire port. With the 1-Wire port, the memory and control
functions will not be available until the ROM function protocol has been established. The master must
first provide one of four ROM function commands: 1) Read ROM, 2) Match ROM, 3) Search ROM, or 4)
Skip ROM. These commands operate on the 64-bit lasered ROM portion of each device and can singulate
a specific device if many are present on the 1-Wire line as well as indicate to the bus master how many
and what types of devices are present. After a ROM function sequence has been successfully executed,
the memory and control functions are accessible and the master may then provide any one of the six
memory and control function commands.
2, 4, 7, 10,
12, 14, 15
PIN
11
13
16
1
3
5
6
8
9
SYMBOL
VSENS+
VSENS-
AGND
VAD
GND
V
DQ
NC
X2
X1
DD
DESCRIPTION
Data Input/Out: for 1-Wire operation: open drain
ADC Input: input for general purpose A/D
Battery Input: connection for battery current to be monitored (see text)
Battery Input: connection for battery current to be monitored (see text)
Analog Ground: must be at the same potential as GND
Digital Ground: must be at the same potential as AGND
Crystal Input: connection for 32.768 kHz for RTC operation
Crystal Input: connection for 32.768 kHz for RTC operation
V
No Connect
DD
Pin: input supply voltage
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DS2437