Datasheet

Pin Descriptions
DCMD
Discharge-before-charge control input
The DCMD
input controls the conditions
that enable discharge-before-charge. DCMD
is pulled up internally. A negative-going
pulse on DCMD
initiates a discharge to end-
of-discharge voltage (EDV) on the BAT pin,
followed by a new charge cycle start. Tying
DCMD
to ground enables automatic
discharge-before-charge on every new charge
cycle start.
DSEL
Display select input
This three-state input configures the charge
status display mode of the LED
1
and LED
2
outputs. See Table 2.
VSEL
Voltage terminationselect input
This three-state input controls the voltage-
termination technique used by the bq2004.
When high, PVD is active. When floating,
-∆V is used. When pulled low, both PVD and
-∆V are disabled.
TM
1
–
TM
2
Timer mode inputs
TM
1
and TM
2
are three-state inputs that
configure the fast charge safety timer, voltage
termination hold-off time, “top-off”, and
trickle charge control. See Table 1.
TCO
Temperature cut-offthreshold input
Input to set maximum allowable battery
temperature. If the potential between TS
and SNS is less than the voltage at the TCO
input, then fast charge or top-off charge is ter
-
minated.
TS
Temperature senseinput
Input, referenced to SNS, for an external
thermister monitoring battery temperature.
BAT
Battery voltage input
BAT is the battery voltage sense input, refer
-
enced to SNS. This is created by a high-
impedance resistor-divider network con
-
nected between the positive and the negative
terminals of the battery.
SNS
Charging current sense input
SNS controls the switching of MOD based on
an external sense resistor in the current
path of the battery. SNS is the reference po
-
tential for both the TS and BAT pins. If
SNS is connected to V
SS
, then MOD switches
high at the beginning of charge and low at
the end of charge.
LED
1
–
LED
2
Charge status outputs
Push-pull outputs indicating charging
status. See Table 2.
V
SS
Ground
V
CC
V
CC
supply input
5.0V,±10% powerinput.
MOD
Charge current control output
MOD is a push-pull output that is used to
control the charging current to the battery.
MOD switches high to enable charging cur-
rent to flow and low to inhibit charging
current flow.
DIS
Discharge control output
Push-pull output used to control an external
transistor to discharge the battery before
charging.
INH
Charge inhibit input
When low, the bq2004 suspends all charge
actions, drives all outputs to high imped
-
ance, and assumes a low-power operational
state. When transitioning from low to high,
a new chargecycle is started.
2
bq2004