MAX1666S Datasheet, PDF (12/16 Pages) Maxim Integrated Products – Advanced Lithium-Ion Battery-Pack Protector

Advanced Lithium-Ion
Battery-Pack Protector
Overcharge/Overdischarge
Current Protection
The MAX1666 checks for overcharge or overdischarge
current in standby and sample states. The thresholds
are factory preset to 200mV and 300mV, respectively.
A charge current makes PKN go below GND. A dis-
charge current makes PKN go above GND. When PKN
exceeds the threshold, a fault is acknowledged. CGO
goes high when the overcharge threshold is exceeded.
DSO goes high when the overdischarge threshold is
exceeded. An internal 550ms timer starts. At the end of
550ms, DSO or CGO goes low, while the MAX1666
rechecks for an overcharge/overdischarge fault. A per-
sistent fault causes DSO and CGO to return high and
restarts the 550ms timer again.
Truth Table
The MAX1666 has a total of eight signal inputs and six
outputs. Table 2 lists all the possible states.
Applications Information
Choosing an External MOSFET
The external P-channel MOSFETs act as a gated switch
to enable or disable the charging/discharging process.
CGO controls the MOSFET for normal charging of the
battery. TKO controls the MOSFET for trickle charge of
the cells. DSO controls the discharging MOSFET. Use
different MOSFETs to optimize each function depending
on the maximum charge and discharge rates. Table 3
lists some suitable MOSFETs in a small SO-8 package.
Layout Considerations and Bypassing
As with all printed circuit board designs, a careful lay-
out is suggested. Minimize lead lengths to reduce loss-
es in the traces.
Table 3. MOSFET Selection
P-CHANNEL MOSFETs MAXIMUM DRAIN CURRENT (A)
IRF7404
5.3
IRF7406
4.7
Si4431
4.5
Si4947 (dual)
2.5 EA
12 ______________________________________________________________________________________