AAT3680
Lithium-Ion/Polymer
Linear Battery Charge Controller
Charge Status
Sleep / Charge Complete
Temp., OC, OV Fault
Battery Conditioning
Output Status
STAT Level
HI / HI / HI / HI
LO / LO / HI / HI
LO / LO / LO / LO
LO / LO / LO / HI
LO / HI / HI / HI
Constant Current Mode
Constant Voltage Mode
Figure 4: Microcontroller Interface Logic Output.
maximum battery charge constant voltage thresh-
Protection Circuitry
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.
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.
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.
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
Preconditioning
(Trickle Charge)
Phase
Constant Current
Phase
Constant Voltage
Phase
Output Charge
Voltage (VCH
)
Preconditioning
Voltage Threshold
(VMIN
)
Regulation
Current
(ICHARGE(REG)
)
Trickle Charge
and Termination
Threshold
Figure 5: Typical Charge Profile.
3680.2006.03.1.6
9
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
