AAT3680
Lithium-Ion/Polymer
Linear Battery Charge Controller
Charge Status
Sleep / Charge Complete
Temp., OC, OV Fault
Battery Conditioning
Constant Current Mode
Constant Voltage Mode
Output Status
HI / HI / HI / HI
LO / LO / HI / HI
LO / LO / LO / LO
LO / LO / LO / HI
LO / HI / HI / HI
STAT Level
Figure 4: Microcontroller Interface Logic Output.
Protection Circuitry
The AAT3680 is a highly integrated battery man-
agement system IC including several protection
features. In addition to battery temperature moni-
toring, the IC constantly monitors for over-current
and over-voltage conditions. If an over-current sit-
uation occurs, the AAT3680 latches off the pass
device to prevent damage to the battery or the sys-
tem, and enters shutdown mode until the over-cur-
rent event is terminated.
An over-voltage condition is defined as a condition
where the voltage on the BAT pin exceeds the
maximum battery charge voltage. If an over-volt-
age condition occurs, the IC turns off the pass
device until voltage on the BAT pin drops below the
maximum battery charge constant voltage thresh-
old. The AAT3680 will resume normal operation
after the over-current or over-voltage condition is
removed. During an over-current or over-voltage
event, the STAT will report a FAULT signal.
In the event of a battery over-temperature condi-
tion, the IC will turn off the pass device and report
a FAULT signal on the STAT pin. After the system
recovers from a temperature fault, the IC will
resume operation in the 1X trickle charge mode to
prevent damage to the system in the event a defec-
tive battery is placed under charge. Once the bat-
tery voltage rises above the trickle charge to con-
stant current charge threshold, the IC will resume
the constant current mode.
Preconditioning
(Trickle Charge)
Phase
Constant Current
Phase
Constant Voltage
Phase
Output Charge
Voltage (V
CH
)
Preconditioning
Voltage Threshold
(V
MIN
)
Regulation
Current
(I
CHARGE(REG)
)
Trickle Charge
and Termination
Threshold
Figure 5: Typical Charge Profile.
3680.2006.03.1.6
9
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
