BQ27505-J4 Datasheet, PDF (33/38 Pages) Texas Instruments – System-Side Impedance Track™ Fuel Gauge

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bq27505-J4
SLVSA40 – DECEMBER 2009
6.1.3 Reading Application Status
The Application Status data flash location contains cell profile status information, and can be read using
the ApplicationStatus( ) extended command (0x6a). The bit configuration of this function/location is shown
in Table 6-1.
Table 6-1. ApplicationStatus( ) Bit Definitions
Application
bit7
bit6
bit5
bit4
bit3
bit2
bit1
Configuration
Byte
—
—
—
—
—
—
—
LU_PROF = Last profile used by fuel gauge. Cell0 last used when cleared. Cell1 last used when set. Default is 0.
bit0
LU_ PROF
6.2 APPLICATION-SPECIFIC FLOW AND CONTROL
The bq27505-J4 supports only one type of battery profile. This profile is stored in both the Def0 and Def1
profiles. When a battery pack is inserted for the first time, the default profile is copied into the Packn
profiles. Then the Impedance Track™ algorithm begins gas gauging, regularly updating Packn as the
battery is used.
When an existing pack is removed from the bq27505-J4 and a different (or same) pack is inserted, cell
impedance is measured immediately after battery detection (see section First OCV and Impedance
Measurement). The bq27505-J4 chooses the profile which is closest to the measured impedance, starting
with the Pack n profiles. That is, if the measured impedance matches Pack 0, then the Pack 0 profile is
used. If the measured impedance matches Pack 1, then the Pack 1 profile is used. If the measured
impedance does not match the impedance stored in either Pack 0 or Pack 1, the battery pack is deemed
new (none of the previously used packs). Either Def0/Def1 profile is copied into either the Pack 0 or Pack
1 profile, overwriting the oldest Pack n profile.
7 COMMUNICATIONS
7.1 I²C INTERFACE
The bq27505-J4 supports the standard I²C read, incremental read, quick read, one byte write, and
incremental write functions. The 7 bit device address (ADDR) is the most significant 7 bits of the hex
address and is fixed as 1010101. The 8-bit device address will; therefore, be 0xAA or 0xAB for write or
read, respectively.
Host generated
bq27505 generated
S ADDR[6:0] 0 A CMD [7:0] A DATA [7:0] A P
S ADDR[6:0] 1 A DATA [7:0]
(a) 1-byte write
(b) quick read
S ADDR[6:0] 0 A CMD [7:0] A Sr ADDR[6:0] 1 A DATA [7:0] N P
(c) 1- byte read
NP
S ADDR[6:0] 0 A
CMD [7:0]
A Sr ADDR[6:0] 1 A
(d) incremental read
DATA [7:0]
A ...
DATA [7:0]
NP
S ADDR[6:0] 0 A CMD[7:0] A DATA [7:0] A DATA [7:0]
(e) incremental write
(S = Start , Sr = Repeated Start , A = Acknowledge , N = No Acknowledge , and P = Stop).
A ... A P
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COMMUNICATIONS
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