BQ27541-V200_1007 Datasheet, PDF (33/43 Pages) Texas Instruments – Single Cell Li-Ion Battery Fuel Gauge for Battery Pack Integration

bq27541-V200
www.ti.com
SLUSA11 – FEBRUARY 2010
HDQ serial communication is normally initiated by the host processor sending a break command to the bq27541.
A break is detected when the DATA pin is driven to a logic-low state for a time t_(B) or greater. The DATA pin
should then be returned to its normal ready high logic state for a time t_(BR). The bq27541 is now ready to receive
information from the host processor.
The bq27541 is shipped in the I2C mode. TI provides tools to enable the HDQ peripheral.
HDQ HOST INTERRUPTION FEATURE
The default bq27541 behaves as an HDQ slave only device. If the HDQ interrupt function is enabled, the
bq27541 is capable of mastering and also communicating to a HDQ device. There is no mechanism for
negotiating who is to function as the HDQ master and care must be taken to avoid message collisions. The
interrupt is signaled to the host processor with the bq27541 mastering an HDQ "message". This message is a
fixed message that will be used to signal the interrupt condition. The message itself is 0x80 (slave write to
register 0x00) with no data byte being sent as the command is not intended to convey any status of the interrupt
condition. The HDQ interrupt function is not public and needs to be enabled by command.
When the SET_HDQINTEN subcommand is received, the bq27541 will detect any of the interrupt conditions and
assert the interrupt at one second intervals until the CLEAR_HDQINTEN command is received or the count of
HDQHostIntrTries has lapsed.
The number of tries for interrupting the host will be determined the data flash parameter named
Configuration.Register.HDQHostIntrTries.
Low Battery Capacity
This feature will work identically to SOC1. It will use the same data flash entries as SOC1 and will trigger
interrupts as long as SOC1 = 1.
Temperature
This feature will work identically to Charge Inhibit. It will used the same DF entries as Charge Inhibit and will
trigger interrupts as long as CHG_INH = 1.
Copyright © 2010, Texas Instruments Incorporated
Product Folder Link(s): bq27541-V200
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