BQ2060A_15 Datasheet, PDF (16/61 Pages) Texas Instruments – SBS v1.1-Compliant Gas Gauge IC

bq2060A
SLUS500D – OCTOBER 2001 – REVISED OCTOBER 2011
www.ti.com
Primary Charge Termination
The bq2060A terminates charge if it detects a charge-termination condition. A charge-termination condition
includes the following.
• ΔT/Δt:For ΔT/Δt, the bq2060A detects a change in temperature over many seconds. The ΔT/Δt 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 ΔT/Δt 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, ΔT/Δt detection is suspended. If Current()
drops below 256 mA or Temperature() below 25°C, the holdoff 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 bq2060A 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 80 s. The bq2060A uses
the VFC to measure current for current taper termination. The current must also remain above 0.5625/R_S mA
to qualify the termination condition.
Once the bq2060A detects a primary charge termination, it 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 bq2060A 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. The programmed percentage of FCC, Fast Charge
Termination %, is set in EE 0x4b. The bq2060A clears the FULLY_CHARGED bit when RelativeStateOfCharge()
is less than the programmed Fully Charged Clear %. The bq2060A broadcasts the fast-charge rate when the
FULLY_CHARGED bit is cleared and voltage and temperature permit. The bq2060A clears the
TERMINATE_CHARGE_ALARM when it no longer detects that the battery is being charged or it no longer
detects the termination condition. See Table 6 for a summary of BatteryStatus() alarm and status bit operation.
Display Port
General
The display port drives a 4- or 5-LED bar-graph display. The display is activated by a logic signal on the DISP
input. The bq2060A can display RM in either a relative or absolute mode with each LED representing a
percentage of the full-battery reference. In relative mode, the bq2060A uses FCC as the full-battery reference; in
absolute mode, it uses DC.
The DMODE bit in Pack Configuration programs the bq2060A for the absolute or relative display mode. The LED
bit in Control Mode programs the 4- or 5-LED option. A 5th LED can be used with the 4-LED display option to
show when the battery capacity is ≥ to 100%.
Activation
The display may be activated at any time by a high-to-low transition on the DISP input. This is usually
accomplished with a pullup resistor and a pushbutton switch. Detection of the transition activates the display and
starts a 4-s display timer. The timer expires and turns off the display whether DISP was brought low momentarily
or held low indefinitely. Reactivation of the display requires that the DISP input return to a logic-high state and
then transition low again. The second high-to-low transition must occur after the display timer expires. The
bq2060A requires the DISP input to remain stable for a minimum of 250 ms to detect the logic state.
If the EDV0 bit is set, the bq2060A disables the LED display. The display is also disabled during a VFC
calibration and should be turned off before entering low-power storage mode.
Display Modes
In relative mode, each LED output represents 20% or 25% of the RelativeStateOfCharge() value. In absolute
mode, each LED output represents 20% or 25% of the AbsoluteStateOfCharge() value. Table 7 and Table 8
show the display operation.
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