BQ2023 Datasheet, PDF (12/27 Pages) Texas Instruments – SINGLE-WIRE ADVANCED BATTERY MONITOR IC FOR CELLULAR AND PDA APPLICATIONS

bq2023
SINGLEĆWIRE ADVANCED BATTERY MONITOR IC
FOR CELLULAR AND PDA APPLICATIONS
SLUS480B – MAY 2001
APPLICATION INFORMATION
initialization and selected states
initialization
After the SDQ pin has been driven low for at least 480 µs and then is driven high, the bq2023 will issue a
presence pulse. After the presence pulse is sent, the bq2023 is initialized.
selected
After successful completion of a ROM function command, the bq2023 is in the selected state.
ROM function commands
Figure 8 illustrates the four ROM function commands. On the successful completion of a ROM function
command, the bq2023 will respond to a memory/status function command.
read ROM
When the bq2023 is initialized, the read ROM command, 33 hex, directs the bq2023 to transmit the contents
of the 64 bit ID ROM in order, starting with the least significant bit 0. After the bq2023 transmits the 64th bit, the
bq2023 is in the selected state.
match ROM
When the bq2023 is initialized, the match ROM command, 55 hex, directs the bq2023 to compare the next 64
bits received to its own ID ROM contents. If each of the received bits matches, then the bq2023 is selected.
search ROM
When the bq2023 is initialized, the search ROM command, F0 hex, directs the bq2023 to transmit each bit of
the ID ROM twice but in a different form each time, and then to receive a bit. First the true value of the bit is
transmitted; then the complement of the bit is transmitted. Then, the bq2023 receives a bit. This received bit
is compared to the true bit. This process is repeated and the bq2023 compares all bits received to the contents
of the ID ROM. If the received bits match the contents of the ID ROM the bq2023 is selected.
skip ROM
When the bq2023 is initialized, the SKIP ROM command, CC hex, directs the bq2023 to be selected.
memory function commands
Six memory function commands allow reading of all registers, flash, and RAM, and allow modification of flash
and RAM locations. There are two types of read-memory command, the write data memory, the program profile
byte command, and the flash erase command. The bq2023 responds to the memory function commands only
after it is selected by a ROM function command.
read memory-page CRC
The read memory/page CRC command reads part or all of the 271 memory addresses shown in the register
map with 8-bit CRCs generated at 32-byte page boundaries.
The flowchart in Figure 9 illustrates that when the bq2023 is in the selected state, the read memory/page CRC
command, C3 hex, directs the bq2023 to load the next two bytes (low byte and high byte of the starting address)
into the address counter. Individual bytes of address and data are transmitted least significant bit first. An 8-bit
CRC of the command byte and address bytes is computed and transmitted by the bq2023. When the bq2023
detects a start frame for read time slots it transmits data from the 271 bytes of data memory field as pointed to
by the address counter. After each byte of data is transmitted, the address counter is incremented. If the end
of a page is reached, the bq2023 calculates and transmits an 8-bit CRC that is the result of shifting into the CRC
generator all of the data bytes from the initial starting byte to the last byte of the current page. Once the 8-bit
CRC has been transmitted, data are transmitted from memory as pointed to by the address counter, which at
this point is the start of the next page. This sequence will continue until the final page and its accompanying CRC
are transmitted. The read memory/page CRC command sequence can be terminated at any point by issuing
a reset pulse.
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