BQ2954 Datasheet, PDF (2/18 Pages) Texas Instruments – Lithium Ion Charge Management IC with Integrated Switching Controller

bq2954
Pin Descriptions
TPWM
TM
Time-out programming input
Sets the maximum charge time. The resistor
and capacitor values are determined using
Equation 5. Figure 10 shows the resistor/ca-
pacitor connection.
CHG
Charge active output
An open-drain output is driven low when the
battery is removed, during a temperature
pend, when a fault condition is present, or
when charge is done. CHG can be used to
disable a high-value load capacitor to detect
quickly any battery removal.
BAT
Battery voltage input
Sense input. This potential is generally de-
veloped using a high-impedance resistor di-
vider network connected between the posi-
tive and the negative terminals of the bat-
tery. See Figures 6 and 7 and Equation 1.
VCOMP Voltage loop compensation input
Connects to an external R-C network to sta-
bilize the regulated voltage.
ICOMP Current loop compensation input
Connects to an external R-C network to sta-
bilize the regulated current.
ITERM Charge full and minimum current termi-
nation select
Three-state input is used to set IFULL and
IMIN for fast charge termination. See Table 4.
SNS
Charging current sense input
Battery current is sensed via the voltage devel-
oped on this pin by an external sense-resistor.
TS
Temperature sense input
Used to monitor battery temperature. An exter-
nal resistor-divider network sets the lower and
upper temperature thresholds. (See Figures 8
and 9 and Equations 3 and 4.)
BTST
LCOM
V_SS
V_CC
MOD
LED₁–
LED₂
DSEL
CSEL
Regulation timebase input
Uses an external timing capacitor to ground
to set the pulse-width modulation (PWM)
frequency. See Equation 7.
Battery test output
Driven high in the absence of a battery in or-
der to provide a potential at the battery ter-
minal when no battery is present.
Common LED output
Common output for LED1-2. This output is
in a high-impedance state during initiali-
zation to read programming input on DSEL
and CSEL.
Ground
V_CC supply
5.0V, ±10%
Current-switching control output
Pulse-width modulated push/pull output used
to control the charging current to the battery.
MOD switches high to enable current flow and
low to inhibit current flow. (The maximum
duty cycle is 80%.)
Charger display status 1–2 outputs
Drivers for the direct drive of the LED dis-
play. These outputs are tri-stated during
initialization so that DSEL and CSEL can be
read.
Display select input (shared pin with
LED₂)
Three-level input that controls the LED1–2
charge display modes.
Charge sense-select input (shared pin
with LED₁)
Input that controls whether current is
sensed on low side of battery or high side of
battery. A current mirror is required for
high-side sense.
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