1
Features
c216 Safe management of fast charge
for NiCd and NiMH battery
packs.
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
peak voltahge (PVD), 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 bq24400 is a programmable,
monolithic IC for fast-charge manage-
ment of nickel cadmium (NiCd) and
nickel metal-hydride (NiMH) batter-
ies.
The bq24400 provides a number of
charge termination criteria:
c108 Peak voltage, PVD (for NiCd and
NiMH)
c108 Maximum temperature
c108 Maximum charge time
For safety, the bq24400 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
bq24400 uses trickle-charge to
condition the battery. For NiMH
batteries, the bq24400 provides an
optional top-off charge to maximize
the battery capacity.
The integrated high-frequency com-
parator allows the bq24400 to be the
basis for a complete, high-efficiency
power-conversion circuit.
bq24400
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
SLUS498 -SEPTEMBER 2001
TS Temperature-sense
input
RC Timer-program input
V
CC Supply-voltage input
MOD Modulation-control
output