BQ27510-G1 Datasheet, PDF(23/39 Page) Texas Instruments – System-Side Impedance Track™ Fuel Gauge With Direct Battery Connection

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bq27510-G1

www.ti.com ..................................................................................................................................................................................................... SLUS927 â APRIL 2009

RESCAP = No-load rate of compensation is applied to the reserve capacity calculation. True when set. Default is 0.

BAT_GD override bit. If the gauge enters HIBERNATE only due to the cell voltage, the BAT_GD will not

BATG_OVR = negate. True when set. Default is 0. If both current and voltage are below the HIBERNATE thresholds, the

voltage condition check above is precedent over the current condition check

PFC_CFG1/PFC_CFG0 =

Pin function code (PFC) mode selection: PFC 0, 1, or 2 selected by 0/0, 0/1, or 1/0, respectively. Default is

PFC 1 (0/1).

IWAKE/RSNS1/RSNS0 = These bits configure the current wake function (see Table 11). Default is 0/0/1.

IDSELEN = Enables cell profile selection feature. True when set. Default is 1.

SLEEP = The fuel gauge can enter sleep, if operating conditions allow. True when set. Default is 1.

RMFCC = RM is updated with the value from FCC, on valid charge termination. True when set. Default is 1

BATL_POL = BAT_LOW pin is active-high. True when set. Default is 1.

BATG_POL = BAT_LOW/BAT_GD pin is active-low. True when cleared. Default is 0.

BAT_FN = Selects BAT_LOW (bit clear) or /BAT_GD (bit set) function on pin 12. Default is 0.

TEMPS = Selects external thermistor for Temperature( ) measurements. True when set. Default is 1.

Pin Function Code Descriptions

The bq27510 has three possible pin-function variations that can be selected in accordance with the circuit

architecture of the end application. Each variation has been assigned a pin function code, or PFC.

When the PFC is set to 0, only the bq27510 measures battery temperature under discharge and relaxation

conditions. The charger does not receive any information from the bq27510 about the temperature readings, and

therefore operates open-loop with respect to battery temperature.

A PFC of 1 is like a PFC of 0, except temperature is also monitored during battery charging. If charging

temperature falls outside of the preset range defined in data flash, a charger can be disabled via the

BAT_LOW/BAT_GD pin, until cell temperature recovers. See Section Charge Inhibit for additional details.

Finally when the PFC is set to 2, the battery thermistor can be shared between the fuel gauge and the charger.

The charger has full usage of the thermistor during battery charging, while the fuel gauge uses the thermistor

exclusively during discharge and battery relaxation.

The PFC is specified in Operation Configuration [PFC_CFG1, PFC_CFG0]. The default is PFC = 1.

BAT_LOW/BAT_GD Pin

The BAT_LOW/BAT_GD is a multiplex pin. The function is defined by [BAT_FN] as a system processor with an

electrical indicator of battery status. It the BAT_LOW function is activated, the signaling on the multiplexed pin

follows the status of the [SOC1] bit in the Flags( ) register. Note that the polarity of the pin output can be inverted

via the [BATL_POL] bit of the Operation Configuration.

The bq27510 must operate in conjunction with other electronics in a system appliance, such as chargers or other

ICs and application circuits that draw appreciable power. After a battery is inserted into the system, there should

be no charging or discharging current higher than C/20, so that an accurate OCV can be read. The OCV is used

for helping determine which battery profile to use, as it constitutes part of the battery impedance measurement.

When a battery is inserted into a system, the Impedance Trackâ¢ algorithm requires that no charging of the

battery takes place and that any discharge is limited to less than C/20âthese conditions are sufficient for the fuel

gauge to take an accurate OCV reading. To disable these functions, the BAT_LOW/BAT_GD pin is merely

negated from the default setting. Once an OCV reading has be made, the BAT_LOW/BAT_GD pin is asserted,

thereby enabling battery charging and regular discharge of the battery. The Operation Configuration

[BATG_POL] bit can be used to set the polarity of the battery good signal, should the default configuration need

to be changed.

In PFC 1, the BAT_LOW/BAT_GD pin is also used to disable battery charging when the bq27510 reads battery

temperatures outside the range defined by [Charge Inhibit Temp Low, Charge Inhibit Temp High]. The

BAT_LOW/BAT_GD line is returned to deserted state once temperature falls within the range [Charge Inhibit

Temp Low + Temp Hys, Charge Inhibit Temp High â Temp Hys].

Product Folder Link(s): bq27510-G1

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