11

bq27320

www.ti.com

SLUSCG9A – FEBRUARY 2016 – REVISED MARCH 2016

Product Folder Links: bq27320

Submit Documentation Feedback

Copyright © 2016, Texas Instruments Incorporated

Feature Description (continued)

Information is accessed through a series of commands, called Standard Commands. Further capabilities are

provided by the additional Manufacturer Access Control subcommand set. Both sets of commands, indicated by

the general format Command(), are used to read and write information contained within the device control and

status registers, as well as its data flash locations. Commands are sent from system to gauge using the bq27320

manufacture, or end-equipment operation.

Cell information is stored in the device in non-volatile flash memory. Many of these data flash locations are

accessible during application development. They cannot, generally, be accessed directly during end-equipment

operation. Access to these locations is achieved by either use of the bq27320 device’s companion evaluation

software, through individual commands, or through a sequence of data-flash-access commands. To access a

desired data flash location, the correct data flash address must be known.

The key to the bq27320 device’s high-accuracy gas gauging prediction is Texas Instruments CEDV algorithm.

This algorithm uses cell measurements, characteristics, and properties to create state-of-charge predictions

across a wide variety of operating conditions and over the lifetime of the battery.

The device measures charge and discharge activity by monitoring the voltage across a small-value series sense

resistor (5 m

attached to the device, FCC is learned based on cell current and on cell voltage under-loading conditions when

the EDV2 threshold is reached.

The device external temperature sensing is optimized with the use of a high accuracy negative temperature

coefficient (NTC) thermistor with R25 = 10.0 k

Ω ±1%. B25/85 = 3435K ± 1% (such as Semitec NTC 103AT).

Alternatively, the bq27320 can also be configured to use its internal temperature sensor or receive temperature

data from the host processor. When an external thermistor is used, a 18.2-k

Ω pull-up resistor between BI/TOUT

and TS pins is also required. The bq27320 uses temperature to monitor the battery-pack environment, which is

used for fuel gauging and cell protection functionality.

To minimize power consumption, the device has different power modes: NORMAL, SNOOZE, SLEEP,

HIBERNATE, and BAT INSERT CHECK. The bq27320 passes automatically between these modes, depending

upon the occurrence of specific events, though a system processor can initiate some of these modes directly.

For complete operational details, refer to the bq27320 Technical Reference Manual (SLUUBE6).

NOTE

Formatting Conventions in this Document:

Commands:

italics

with

parentheses()

and

no

breaking

spaces;

for

example,

RemainingCapacity()

Data Flash: italics, bold, and breaking spaces; for example, Design Capacity

Register bits and flags: italics with brackets [ ]; for example, [TDA]

Data flash bits: italics, bold, and brackets [ ]; for example, [LED1]

Modes and states: ALL CAPITALS, for example; UNSEALED mode

8.3.1 Data Commands

8.3.1.1 Standard Data Commands

The bq27320 uses a series of 2-byte standard commands to enable system reading and writing of battery

information. Each standard command has an associated command-code pair, as indicated in Table 1 (see the

bq27320 Technical Reference Manual [SLUUBE6]). Because each command consists of two bytes of data, two

corresponding two bytes of data.