BQ24085_17 Datasheet, PDF (19/42 Pages) Texas Instruments – 750-mA Single-Chip Li-Ion and Li-Pol Charge Management IC With Thermal Regulation

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bq24085, bq24086, bq24087, bq24088
SLUS784E – DECEMBER 2007 – REVISED DECEMBER 2015
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I_TMR Current - mA
Figure 14. bq24085/6/7/8 Oscillator Linearity vs I_TMR
R_TMR 30 KΩ – 100 KΩ
8.3.12 Charge Termination Detection and Recharge
The charging current is monitored during the voltage regulation phase. Charge termination is indicated at the
STATx pins (STAT1 = Hi-Z; STAT2 = Low ) once the charge current falls below the termination current threshold
I_(TERM). A deglitch period t_DGL(TERM) is added to avoid false termination indication during transient events.
Charge termination is not detected if the charge current falls below the termination threshold as a result of the
thermal loop activation. Termination is also not detected when charger enters the suspend mode, due to
detection of invalid pack temperature or internal thermal shutdown.
Table 6 describes the termination latch functionality.
Table 6. Termination Latch Functionality
TERMINATION DETECTED LATCHED WHEN
I_(OUT) < I_(TERM) AND t > t_DGL(TERM) AND V_(OUT) > V_(RCH)
TERMINATION LATCH RESET AT
CE rising edge or OVP detected
New charging cycle started; see state diagram
Termination disabled
The termination function is DISABLED:
1. In bq24085/6/7/8 the termination is disabled when the TMR pin is left open (floating).
2. In bq24087, leaving the TMR pin open (floating) does not disable the termination. The only way to disabled
termination in bq24087 is to have TE = high.
3. Thermal regulation or thermal shutdown.
4. Invalid battery pack temperature (TS fault).
8.3.13 Battery Absent Detection – Voltage Mode Algorithm
The bq24085/6/7/8 provides a battery absent detection scheme to reliably detect insertion and removal of battery
packs. The detection circuit applies an internal current to the battery terminal, and detects battery presence
based on the terminal voltage behavior. Figure 15 has a typical waveform of the output voltage when the battery
absent detection is enabled and no battery is connected.
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