bq24401
Programmable NiCd/NiMH
Fast-Charge Management Device
Features
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Safe management of fast charge
for NiCd and NiMH
High-frequency switching con-
troller for efficient and simple
charger design
Pre-charge qualification for
detecting shorted, damaged, or
overheated cells
Fast-charge termination by
鈭員/鈭唗
maximum temperature,
and maximum charge time
Selectable top-off mode for
achieving maximum capacity in
NiMH batteries
Programmable trickle-charge
mode for reviving deeply dis-
charged batteries and for post-
charge maintenance
Built-in battery removal and in-
sertion detection
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
b q 2 4 4 0 1 p r ov i de s a n u m b e r o f
charge termination criteria:
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Rate of temperature rise,
鈭員/鈭唗
(for NiCd and NiMH)
Maximum temperature
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
t he l o w - v o l t a g e t h r es ho l d , t h e
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.
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Pin Connections
Pin Names
SNS
V
SS
Current-sense input
System ground
Charge-status
output
Battery-voltage
input
TS
RC
V
CC
MOD
Temperature-sense
input
Timer-program input
Supply-voltage input
Modulation-control
output
SNS
VSS
LED
BAT
1
2
3
4
8
7
6
5
MOD
VCC
RC
TS
LED
BAT
8-Pin DIP or Narrow SOIC
or TSSOP
PN-2000.eps
SLUS497鈥揝EPTEMBER 2001
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