BQ35100 Datasheet, PDF (14/26 Pages) Texas Instruments – Lithium Primary Battery Fuel Gauge

bq35100
SLUSCM6A – JUNE 2016 – REVISED JULY 2016
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S
ADDR[6:0]
0 A CMD[7:0] N P
Figure 8. Attempt To Read an Address Above 0x7F (Nack Command)
S ADDR[6:0] 0 A CMD[7:0] A DATA[7:0]
A DATA[7:0] N _{. . .} N P
Figure 9. Attempt at Incremental Writes (nack All Extra Data Bytes Sent)
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 0x7F
Data From
addr 0x00
Figure 10. Incremental Read at the Maximum Allowed Read Address
The I²C engine releases both SDA and SCL if the I²C bus is held low for Bus Low Time. If the gas 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.
7.4 Device Functional Modes
The bq35100 is intended for systems where the battery electronics are required to consume a very low average
current. To achieve this, the device is intended to be fully powered off when not required through control of the
GAUGE_ENABLE (GE) pin. When this pin is low, then the device is fully powered down with no measurements
being made and no data, unless in flash, is retained.
An example system current profile is shown along with the state of GAUGE_ENABLE to reduce the average
power consumption of the battery electronics.
GE HIGH
0
GE LOW
Figure 11. Power Consumption
The average power consumption of the bq35100 is an average of the periods where GAUGE_ENABLE is high
AND low over a given period.
For example, if the system enters a high power state (500 µA) for 30 s every 4 hours, the average current will be:
500 µA × 30 s / 4 h = 1.042 µA
The flowchart below highlights the operational flow and conditional decisions.
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