AAT2550
Total Power Solution for Portable Applications
System Operation Flow Chart
ADP
Voltage
Yes
ADP
Yes
UVLO
Yes
Output
Output
ADPP
ADPP
Switch
Switch
On
On
Test
Power Select
V
P > VUVLO
ADP > VADPP
No
No
Sleep
No
Sleep
Mode
Mode
ADP
ADP
Loop
Loop
Enable
Timing
Power On
Power On
Reset
Reset
Fault
Conditions Monitor
Yes
OV, OT
Thermal
Loop Enable
Enable
Thermal Loop
No
Expire
Shutdown
Shut Down
Mode
No
Mode
Yes
Battery
Temp. Monitor
No
Yes
Yes
Battery
Battery
Device Temp. Monitor
Recharge Test
VRCH > VBAT
No
Temp. Fault
Temp. Fault
<TS<VTS2
VTS1
TJ > 110°C
Charge
Charge
Safety
Timer
Timer
Safety
Yes
Yes
Thermal Loop
Thermal Loop
Current
Current
Low Current
Low Current
Set
Preconditioning Test
VMIN > VBAT
Reduction in ADP
Reduction in ADP
Conditioning
Conditioning
Charging Mode
Charging Mode
Charge
Charge
No
Current
Current
Current Phase Test
Charging
Charging
> VBAT
VCH
Mode
Mode
No
Voltage
Voltage
Yes
Voltage Phase Test
IBAT> IMIN
Charging
Charging
Mode
Mode
No
Charge
Charge
Completed
Completed
junction over-temperature threshold is 140°C with
15°C of hysteresis. Once an over-temperature or
over-current fault conditions is removed, the output
voltage automatically recovers.
Current Limit and Over-Temperature
Protection
For overload conditions, the peak input current is
limited. To minimize power dissipation and stresses
under current limit and short-circuit conditions,
switching is terminated after entering current limit
for a series of pulses. Switching is terminated for
seven consecutive clock cycles after a current limit
has been sensed for a series of four consecutive
clock cycles.
Under-Voltage Lockout
The under-voltage lockout circuit prevents the
device from improper operation at low input volt-
ages. Internal bias of all circuits is controlled via the
VIN input. Under-voltage lockout (UVLO) guaran-
tees sufficient VIN bias and proper operation of all
internal circuitry prior to activation.
Thermal protection completely disables switching
when internal dissipation becomes excessive. The
16
2550.2006.07.1.0
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
