BQ2060SS Datasheet, PDF (14/59 Pages) Texas Instruments – SBS V1.1-COMPLIANT GAS GAUGE IC

bq2060
SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005
www.ti.com
• Overvoltage: An overvoltage condition exists when the bq2060 measures the battery voltage to be more
than the Overvoltage Margin above the ChargingVoltage() or a Li-ion cell voltage has exceeded the
overvoltage limit programmed in Cell Under-/Overvoltage. Overvoltage Margin is programmed in EE 0x48
and Cell Under-/Overvoltage in EE 0x4a (least significant nibble). On detecting an overvoltage condition, the
bq2060 sets the ChargingCurrent() to zero and sets the TERMINATE_CHARGE_ALARM bit in
BatteryStatus(). The bq2060 clears the TERMINATE_ CHARGE_ALARM bit when it detects that the battery
is no longer being charged (DISCHARGING bit set in BatteryStatus()). The bq2060 continues to broadcast
zero charging current until the overvoltage condition is cleared. The overvoltage condition is cleared when
the measured battery voltage drops below the ChargingVoltage() plus the Overvoltage Margin or when the
CVOV bit is reset.
• Over-Temperature: An over-temperature condition exists when Temperature() is greater than or equal to the
Max T value programmed in EE 0x45 (most significant nibble). On detecting an over-temperature condition,
the bq2060 sets the ChargingCurrent() to zero and sets the OVER_TEMP_ALARM and
TERMINATE_CHARGE_ ALARM bit in BatteryStatus() and the CVOV bit in Pack Status. The
over-temperature condition is cleared when Temperature() is equal to or below (Max T– 5°C).
• Overcharge: An overcharge condition exists if the battery is charged more than the Maxmum Overcharge
value after RM = FCC. Maximum Overcharge is programmed in EE 0x2e–0x2f. On detecting an overcharge
condition, the bq2060 sets the ChargingCurrent() to zero and sets the OVER_CHARGED_ALARM,
TERMINATE_CHARGE_ ALARM, and FULLY_CHARGED bits in BatteryStatus(). The bq2060 clears the
OVER_ CHARGED_ALARM and TERMINATE_CHARGE_ ALARM when it detects that the battery is no
longer being charged. The FULLY_CHARGED bit remains set and the bq2060 continues to broadcast zero
charging current until RelativeStateOfCharge() is less than Fully Charged Clear% programmed in EE
0x4c.The counter used to track overcharge capacity is reset with 2mAh of discharge.
• Under-Temperature: An under-temperature condition exists if Temperature() < 0°C. On detecting an
under-temperature condition, the bq2060 sets ChargingCurrent() to zero. The bq2060 sets ChargingCurrent()
to the appropriate pre-charge rate or fast-charge rate when Temperature() ≥ 0°C.
Primary Charge Termination
The bq2060 terminates charge if it detects a charge-termination condition. A charge-termination condition
includes the following.
• ∆T/∆t: For ∆T/∆t, the bq2060 detects a change in temperature over many seconds. The ∆T/∆t setting is
programmable in both the temperature step, DeltaT (1.6°C – 4.6°C), and the time step, DeltaT Time (20
s–320 s). Typical settings for 1°C/minute include 2°C/120 s and 3°C/180 s. Longer times are required for
increased slope resolution. The DeltaT value is programmed in EE 0x45 (least significant nibble) and the
Delta T Time in EE 0x4e.
In addition to the ∆T/∆t timer, a holdoff timer starts when the battery is being charged at more than 255 mA
and the temperature is above 25°C. Until this timer expires, ∆T/∆t detection is suspended. If Current() drops
below 256 mA or Temperature() below 25°C, the hold-off timer resets and restarts only when the current and
temperature conditions are met again. The holdoff timer is programmable (20 s–320 s) with Holdoff Time
value in EE 0x4f.
• Current Taper: For current taper, ChargingVoltage() must be set to the pack voltage desired during the
constant-voltage phase of charging. The bq2060 detects a current taper termination when the pack voltage is
greater than the voltage determined by Current Taper Qual Voltage in EE 0x4f and the charging current is
below a threshold determined by Current Taper Threshold in EE 0x4e, for at least 40 s. The bq2060 uses the
VFC to measure current for current taper termination. The current polarity must remain positive as measured
by the VFC during this time.
Once the bq2060 detects a primary charge termination, the bq2060 sets the TERMINATE_CHARGE_ALARM
and FULLY_CHARGED bits in BatteryStatus(), and sets the ChargingCurrent() to the maintenance charge rate
as programmed in Maintenance Charging Current EE 0x1c–0x1d. On termination, the bq2060 also sets RM to a
programmed percentage of FCC, provided that RelativeStateOfCharge() is below the desired percentage of FCC
and the CSYNC bit in Pack Configuration EE 0x3f is set. If the CSYNC bit is not set and RelativeStateOfCharge()
is less than the programmed percentage of FCC, the bq2060 clears the FULLY_CHARGED bit in
BatteryStatus(). The programmed percentage of FCC, Fast Charge Termination %, is set in EE 0x4b. The
14