BQ27741-G1_14 Datasheet, PDF (18/39 Pages) Texas Instruments – Single Cell Li-Ion Battery Fuel Gauge with Integrated Protection

bq27741-G1
SLUSBF2 – JULY 2013
www.ti.com
I²C Interface
The fuel gauge supports the standard I²C read, incremental read, one-byte write quick read, and 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 is therefore 0xAA or 0xAB for write or read, respectively.
Host Generated
GG Generated
S ADDR[6:0] 0 A CMD[7:0] A DATA[7:0] A PP
S ADDR[6:0] 1 A DATA[7:0]
(a)
(b)
S ADDR[6:0] 0 A CMD[7:0] A Sr ADDR[6:0] 1 A DATA[7:0] N P
( c)
NP
S ADDR[6:0] 0 A CMD[7:0] A Sr ADDR[6:0] 1 A DATA[7:0] A . . . DATA[7:0] N P
(d)
Figure 4. Supported I²C Formats
(a) 1-byte write
(b) Quick read
(c) 1-byte read
(d) Incremental read (S = Start, Sr = Repeated Start, A = Acknowledge, N = No Acknowledge, and P = Stop).
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 fuel gauge 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).
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] N PPP
Attempt to read an address above 0x7F (NACK command):
S ADDR[6:0] 0 A CMD[7:0] N PPP
Attempt at incremental writes (NACK all extra data bytes sent):
S ADDR[6:0] 0 A CMD[7:0] A DATA[7:0] A DATA[7:0] N . . . N P
Incremental read at the maximum allowed read address:
S ADDR[6:0] 0 A CMD[7:0] A Sr ADDR[6:0] 1 A DATA[7:0] A DATA[7:0] N P
Address
0x7F
Data from
addr 0x74
Data from
addr 0x00
The I²C engine releases both SDA and SCL if the I²C bus is held low for t_(BUSERR). If the fuel gauge was holding
the lines, releasing them frees the master to drive the lines. If an external condition is holding either of the lines
low, the I²C engine enters the low-power sleep mode.
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