BQ27505 Datasheet, PDF (27/42 Pages) Texas Instruments – System-Side Impedance Track™ Fuel Gauge

Not Recommended for New Designs
bq27505
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SLUS884 – FEBRUARY 2009
Table 5-3. Operation Configuration Bit Definition
bit7
bit6
bit5
bit4
bit3
bit2
bit1
bit0
High byte
RESCAP BATG_OVR INT_BREM PFC_CFG1 PFC_CFG0
IWAKE
RSNS1
RSNS0
Low byte INT_FOCV IDSELEN
SLEEP
RMFCC
SOCI_POL BATG_POL BATL_POL
TEMPS
RESCAP = No-load rate of compensation is applied to the reserve capacity calculation. True when set. Default is 0.
BATG_OVR = BAT_GD override bit. If the gauge enters Hibernate only due to the cell voltage, the BAT_GD will not negate. True when set.
Default is 0.
INT_BERM = Battery removal interrupt bit. The SOC_INT negates 1ms when the battery removal interrupt is enabled. True when set. The
default is 0.
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 5-6). Default is 0/0/1.
INT_FOCV = Indication of the measurement of the OCV during the initialization. The SOC_INT will negate during the first measurement if
this bit is set. True when set. Default is 0.
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.
SOCI_POL = SOC interrupt polarity is active-low. True when cleared. Default is 0.
BATG_POL = BAT_GD pin is active-low. True when cleared. Default is 0.
BATL_POL = BAT_LOW pin is active-high. True when set. Default is 1.
TEMPS = Selects external thermistor for Temperature( ) measurements. True when set. Default is 1.
Some bq27505 pins are configured via the Operation Configuration B data flash register, as indicated in
Table 5-4. This register is programmed/read via the methods described in Section 4.2.1: Accessing the
Data Flash. The register is located at subclass = 64, offset = 9.
Table 5-4. Operation Configuration B Bit Definition
bit7
bit6
bit5
bit4
bit3
bit2
bit1
bit0
WRTEMP
BIE
BL_INT
GNDSEL
BattGdInit
–
–
–
WRTEMP = Enables the temperature write. The temperature could be written by the host. True when set. Default is 0.
BIE = Battery insertion detection enable. When the battery insertion detection is disabled, the gauge relies on the host command to set the
BAT_DET bit. True when set. Default is 1.
BL_INT = Battery low interrupt enable. True when set. Default is 0.
GNDSEL = The ADC ground select control. The Vss (Pin D1) is selected as ground reference when the bit is clear. Pin A1 is selected when
the bit is set. Default is 1.
BattGdInit = BAT_GD will be asserted during the initialization. It is for application that needs the system be powered up ASAP. True when
set. Default is 0.
5.3.2 Pin Function Code Descriptions
The bq27505 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 bq27505 measures battery temperature under discharge and relaxation
conditions. The charger does not receive any information from the bq27505 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_GD pin until cell temperature recovers. See Section 5.6.2, 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.
5.3.3 BAT_LOW Pin
The BAT_LOW pin provides a system processor with an electrical indicator of battery status. The signaling
on the BAT_LOW pin follows the status of the [SOC1] bit in the Flags( ) register. Note that the polarity of
the BAT_LOW pin can be inverted via the [BATL_POL] bit of Operation Configuration.
Copyright © 2009, Texas Instruments Incorporated
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FUNCTIONAL DESCRIPTION
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