1
Features
c216 Safe management of fast charge
for NiCd and NiMH
c216 High-frequency switching con-
troller for efficient and simple
charger design
c216 Pre-charge qualification for
detecting shorted, damaged, or
overheated cells
c216 Fast-charge termination by
∆T/∆t maximum temperature,
and maximum charge time
c216 Selectable top-off mode for
achieving maximum capacity in
NiMH batteries
c216 Programmable trickle-charge
mode for reviving deeply dis-
charged batteries and for post-
charge maintenance
c216 Built-in battery removal and in-
sertion detection
c216 Sleep mode for low power con-
sumption
General Description
The bq24401 is a programmable,
monolithic IC for fast-charge manage-
ment of nickel cadmium (NiCd) and
nickel metal-hydride (NiMH).
Depending on the chemistry, the
bq24401 provides a number of
charge termination criteria:
c108 Rate of temperature rise, ∆T/∆t
(for NiCd and NiMH)
c108 Maximum temperature
c108 Maximum charge time
For safety, the bq24401 inhibits fast
charge until the battery voltage and
temperature are within user-defined
limits. If the battery voltage is below
the low-voltage threshold, the
bq24401 uses trickle-charge to
condition the battery. For NiMH
batteries, the bq24401 provides an
optional top-off charge to maximize
the battery capacity.
The integrated high-frequency com-
parator allows the bq24401 to be the
basis for a complete, high-efficiency
power-conversion circuit.
bq24401
SNS Current-sense input
V
SS System ground
LED Charge-status
output
BAT Battery-voltage
input
1
PN-2000.eps
8-Pin DIP or Narrow SOIC
or TSSOP
2
3
4
8
7
6
5
SNS
LED
BAT
V
SS
MOD
V
CC
TS
RC
Pin Connections Pin Names
Programmable NiCd/NiMH
Fast-Charge Management Device
SLUS497–SEPTEMBER 2001
TS Temperature-sense
input
RC Timer-program input
V
CC Supply-voltage input
MOD Modulation-control
output