BQ2084DBTR-V150 Datasheet, PDF (26/69 Pages) Texas Instruments – SBS v1.1-COMPLIANT GAS GAUGE WITH LED DELAY

bq2084-V150
SLUS758 – JUNE 2007
Permanent Failure Flag (PF Flag)
PF Flag DF 0x11e contains the flag indicating if the /SAFE output has been activated.
STATE
b7
b6
b5
b4
b3
b2
Clear
0
0
0
0
0
0
Set
0
1
1
0
0
1
PF FLAG
The PF Flag indicates that the SAFE output of the bq2084-V150 has been activated.
0x00 SAFE output high (default)
0x66 SAFE output activated
An example circuit using the SAFE output to blow a fuse is shown in Figure 2.
www.ti.com
b1
b0
0
0
1
0
Figure 2. Example SAFE Circuit Implementation
Low-Power Modes
The bq2084-V150 enters sleep mode when the charge and discharge current is less than the threshold
programmed in Sleep Current Threshold DF 0xfc, the SMBus lines are low for at least 2s, and bit 12 of Misc.
Configuration DF 0x2a is set to zero. Additionally, PRES must be pulled high if the NR bit in Misc Config is set to
0. The bq2084-V150 wakes up periodically to monitor voltage and temperature and to apply self-discharge
adjustment. The sleep period is set in Sleep Timer DF 0xfe. The bq2084-V150 wakes up at a period set by
Sleep Current Multiplier DF 0xfd multiplied by Sleep Time to measure current. The bq2084-V150 comes out of
sleep when either of the SMBus lines go high or when the current is measured and it is greater than the Sleep
Current Threshold.
The sleep current threshold, SLP (mA), is stored in Sleep Current Thresh DF 0xfc as:
Sleep Current Thresh = SLP(mA)/0.5
The wake-up period for current measurement, WAT(s), is set using the following formula:
Sleep Current Multiplier x Sleep Time = WAT(s)
During sleep mode, both charge and discharge FETs are turned off if the NR bit in Misc Config is cleared. If the
bq2084-V150 is in Non-Removable mode where NR=1, then the discharge FET retains its state on entry to
sleep.
Shutdown Mode
The bq2084-V150 goes into shutdown, in which all FETs are turned off and the pack electronics are powered
down (including the bq2084-V150), when SBS.Voltage() falls below Shutdown Voltage DF 0x7c-0x7d and
Voltage at the Pack pin is less than VPACK threshold (DF 0x131, 0x132) both for 2 consecutive samples (1 to 2
s).
26
Submit Documentation Feedback