BQ27425-G1 Datasheet, PDF (24/32 Pages) Texas Instruments – System-Side Impedance Track™ Fuel Gauge With Integrated Sense Resistor

bq27425-G1
SLUSAI6 – NOVEMBER 2011
www.ti.com
I²C INTERFACE
The bq27425 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
bq27425 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 DATA [7:0]
(d) incremental read
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).
Figure 3. Supported I²C Formats
A ... A P
The "quick read" returns data at the address indicated by the address pointer. The address pointer, a register
internal to the I²C communication engine, increments whenever data is acknowledged by the bq27425 or the I²C
master. "Quick writes" function in the same manner and are a convenient means of sending multiple bytes to
consecutive command locations (such as two-byte commands that require two bytes of data).
The following command sequences are not supported:
Attempt to write a read-only address (NACK after data sent by master):
S ADDR[6:0] 0 A CMD[7:0]
A DATA[7:0]
NP
Attempt to read an address above 0x6B (NACK command):
S
ADDR[6:0]
0 A CMD[7:0] N P
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