DS2778G+T&R Maxim Integrated Products, DS2778G+T&R Datasheet - Page 37

• Manufacturer Part Number: DS2778G+T&R
• Description: IC FUEL GAUGE LI+ 2CELL 14-TDFN
• Manufacturer: Maxim Integrated Products

Specifications of DS2778G+T&R

• Function: Fuel, Gas Gauge/Monitor
• Battery Type: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 4 V ~ 9.2 V
• Operating Temperature: -20°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 14-TDFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

This command allows the bus master to specifically
address one DS2775/DS2776 on the 1-Wire bus. Only
the addressed DS2775/DS2776 responds to any sub-
sequent function command. All other slave devices
ignore the function command and wait for a reset pulse.
This command can be used with one or more slave
devices on the bus.
This command saves time when there is only one
DS2775/DS2776 on the bus by allowing the bus master
to issue a function command without specifying the
address of the slave. If more than one slave device is
present on the bus, a subsequent function command
can cause a data collision when all slaves transmit data
at the same time.
This command allows the bus master to use a process
of elimination to identify the 1-Wire net addresses of all
slave devices on the bus. The search process involves
the repetition of a simple three-step routine: read a bit,
read the complement of the bit, then write the desired
value of that bit. The bus master performs this simple
three-step routine on each bit location of the net
address. After one complete pass through all 64 bits,
the bus master knows the address of one device. The
remaining devices can then be identified on additional
iterations of the process. See Chapter 5 in Application
Note 937: Book of iButton Standards for a comprehen-
sive discussion of a net address search, including an
actual example.
After successfully completing one of the net address
commands, the bus master can access the features of
the DS2775/DS2776 with any of the function commands
described in the following paragraphs. The name of
each function is followed by the 8-bit op code for that
command in square brackets. The function commands
are summarized in Table 12. Table 13 details the
requirements for using the function commands.
This command reads data from the DS2775/DS2776
starting at memory address XXh. The LSb of the data in
address XXh is available to be read immediately after
the MSb of the address has been entered. Because the
address is automatically incremented after the MSb of
each byte is received, the LSb of the data at address
XXh + 1 is available to be read immediately after the
MSb of the data at address XXh. If the bus master con-
tinues to read beyond address FFh, data is read start-
Protector and Optional SHA-1 Authentication
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with
______________________________________________________________________________________
Search Net Address [F0h]
Match Net Address [55h]
Function Commands
Skip Net Address [CCh]
Read Data [69h, XXh]
ing at memory address 00h and the address is auto-
matically incremented until a reset pulse occurs.
Addresses labeled Reserved in the Memory Map con-
tain undefined data values (see Table 9). The Read
Data command can be terminated by the bus master
with a reset pulse at any bit boundary. Reads from EEP-
ROM block addresses return the data in the shadow
RAM. A Recall Data command is required to transfer
data from the EEPROM to the shadow. See the Memory
section for more details.
This command writes data to the DS2775/DS2776 start-
ing at memory address XXh. The LSb of the data to be
stored at address XXh can be written immediately after
the MSb of the address has been entered. Because the
address is automatically incremented after the MSb of
each byte is written, the LSb to be stored at address
XXh + 1 can be written immediately after the MSb to be
stored at address XXh. If the bus master continues to
write beyond address FFh, the data starting at address
00 is overwritten. Writes to read-only addresses,
reserved addresses, and locked EEPROM blocks are
ignored. Incomplete bytes are not written. Writes to
unlocked EEPROM block addresses modify the shadow
RAM. A Copy Data command is required to transfer
data from the shadow to the EEPROM. See the Memory
section for more details.
This command copies the contents of the EEPROM
shadow RAM to EEPROM cells for the EEPROM block
containing address XXh. Copy Data commands that
address locked blocks are ignored. While the Copy
Data command is executing, the EEC bit in the EEPROM
register is set to 1 and writes to EEPROM addresses are
ignored. Reads and writes to non-EEPROM addresses
can still occur while the copy is in progress. The Copy
Data command takes t
the next falling edge after the address is transmitted.
See Figure 27 for more information.
This command recalls the contents of the EEPROM
cells to the EEPROM shadow memory for the EEPROM
block containing address XXh.
This command locks (write protects) the block of
EEPROM memory containing memory address XXh.
The LOCK bit in the EEPROM register must be set to 1
before the Lock command is executed. To help pre-
vent unintentional locks, one must issue the Lock com-
mand immediately after setting the LOCK bit (EEPROM
EEC
time to execute, starting on
Recall Data [B8h, XXh]
Write Data [6Ch, XXh]
Copy Data [48h, XXh]
Lock [6Ah, XXh]
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