BQ2019PW Datasheet, PDF (7/27 Pages) Texas Instruments – ADVANCED BATTERY MONITORIC

bq2019
ADVANCED BATTERY MONITOR IC
SLUS465E – DECEMBER 1999 – REVISED FEBRUARY 2003
APPLICATION INFORMATION
BAT+
C1
0.1 µF
HDQ
Q1^†
C3^Ĕ
0.01 µF
U1
REG
STAT
VCC
SR
R3
100 Ω
R4
100 Ω
VSS
HDQ
DC
OSC
D1
5.6 V
R2
R6
100 Ω
100 Ω
D2
5.6 V
R7
100 kΩ
C2
0.1 µF
R1
0.02 Ω
1W
STAT
BAT–
PACK–
R5
100 kΩ
1%
† _{Q1 and C3 are omitted and Vcc is connected to BAT+ for single cell lithium ion applications}
functional description
The bq2019 measures the voltage drop across a low-value series-current sense-resistor between the SR and
VSS pins using a voltage to frequency converter. This information is placed into various internal counter and
timer registers. Using information from the bq2019, the system host can determine the battery state-of-charge,
estimate self-discharge, and calculate the average charge and discharge currents. During pack storage
periods, the use of an internal temperature sensor doubles the self-discharge count rate every 10° above 25°C.
Optionally, the VFC offset is calibrated and automatically compensated for in the charge counter registers.
Access to the registers and control of the bq2019 is accomplished by a single-wire interface through a
register-mapped command protocol that includes placing the device in the low-power mode, resetting the
hardware register, programming flash from RAM, and transferring flash data to RAM.
The bq2019 can operate directly from three or four nickel-chemistry cells or a single Li-Ion cell as long as V_CC
is between 2.8 V and 5.5 V. To reduce cost in multicell applications, power to the bq2019 may be regulated using
a low-cost external FET with the REG pin.
REG output
The bq2019 can operate directly from three or four nickel-chemistry cells or from a single Li-Ion cell as long as
V_CC is between 2.8 V and 5.5 V. To facilitate the power supply requirements of the bq2019, the REG output is
used with an external low-threshold n-JFET when regulation from a higher source potential is required. The
REG output remains active in sleep mode. For applications that do not need the REG output, operating current
is reduced by turning off the operational amplifier with the DISREG bit in the MODE/WOE register. For more
details, refer to the MODE/WOE Register section.
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