BQ2085 Datasheet, PDF (17/56 Pages) Texas Instruments – SBS-COMPLIANT GAS GAUGE IC FOR USE WITH THE bq29311

bq2085
SLUS541 – OCTOBER 2002
DISPLAY PORT
General
The display port drives a 3-, 4-, or 5-LED bar-graph display. The display is activated by a logic signal on the DISP
input. The bq2085 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 bq2085 uses FCC as the full-battery reference;
in absolute mode, it uses Design Capacity (DC).
The DMODE bit in Pack Configuration DF 0x28 programs the bq2085 for the absolute or relative display mode.
The LED bits program the 3-, 4-, or 5-LED option.
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 four second display timer. 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 can be detected only after the
display timer expires. If unused, the DISP input must be pulled up to V_CC.
If the EDV0 bit is set, the bq2085 disables the LED display.
Display Modes
In relative mode, each LED output represents 20%, 25%, or 33% of the RelativeStateOfCharge( ) value. In
absolute mode, each LED output represents 20%, 25% or 33% of the AbsoluteStateOfCharge( ) value. Table 7
shows the display options for 5 LEDs Table 8 for 4 LEDs, and Table 9 for 3 LEDs.
In either mode, the bq2085 blinks the LED display if RemainingCapacity( ) is less than Remaining
CapacityAlarm( ). The display is disabled if EDV0 = 1.
Table 7. Display Mode for Five LEDs
CONDITION
RELATIVE OR ABSOLUTE
StateOfCharge( )
EDV0 = 1
<20%
≥20%, < 40%
≥40%, < 60%
≥60%, < 80%
≥80%
FIVE-LED DISPLAY OPTION
LED1
OFF
ON
ON
ON
ON
ON
LED2
OFF
OFF
ON
ON
ON
ON
LED3
OFF
OFF
OFF
ON
ON
ON
LED4
OFF
OFF
OFF
OFF
ON
ON
LED5
OFF
OFF
OFF
OFF
OFF
ON
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