AAT3601_08 Datasheet, PDF (22/37 Pages) Advanced Analogic Technologies – Total Power Solution for Portable Applications

PRODUCT DATASHEET
AAT3601178
Total Power Solution for Portable Applications
EN_SYS pin
CHGIN
CHGIN_OK
(Internal)
Charger current
ENBAT pin
STAT pin
LED current
SYSTEM ENABLE
(Internal)
SYSOUT
SYSOUT_OK
(Internal)
LDO1
LDO3
LDO5
RSTLPW pin
EN_PE pin
EN_NP pin
LDO2
DC/DC
LDO4
RSTIN pin
0mA
800mA
0mA
0mA
0mA
Battery voltage
0V
Enabling the System
3.4V
3.4V
1.24V
1.85V
800ms
reset
time
1.24V
1.85V
Shutdown
system
Enabling NP
Shutdown NP
3.4V
1.24V
1.85V
10ms
reset
time
Figure 2b: Power Up/Down Sequence; Case 2, Connecting the Adapter Automatically Starts the System.
Watchdog Timer Input (WDI)
The AAT3601 includes an internal watchdog timer that
can be controlled by a μP. After RSTIN goes high, the
watchdog timer must get clock edges on the WDI pin
from the processor. The WDI clock edges must be < 60ms
apart to reset the internal watchdog timer or the RSTIN
pin will become active low.
Battery Charger
Figure 4 illustrates the entire battery charging profile
which consists of three phases.
1. Preconditioning-Current Mode (Trickle) Charge
2. Constant-Current Mode Charge
3. Constant-Voltage Mode Charge
Preconditioning Trickle Charge
Battery charging commences only after the AAT3601 bat-
tery charger checks several conditions in order to main-
tain a safe charging environment. The System Operation
Flow Chart for the Battery Charger operation is shown in
Figure 5. The input supply must be above the minimum
operating voltage (UVLO) and the enable pin (ENBAT)
must be low (it is internally pulled down). When the bat-
tery is connected to the BAT pin, the battery charger
checks the condition of the battery and determines which
charging mode to apply.
Preconditioning-Current
Mode Charge Current
If the battery voltage is below the Preconditioning
Voltage Threshold V_MIN, then the battery charger initiates
precondition trickle charge mode and charges the battery
at 12% of the programmed constant-current magnitude.
For example, if the programmed current is 500mA, then
the trickle charge current will be 60mA. Trickle charge is
a safety precaution for a deeply discharged cell. It also
reduces the power dissipation in the internal series pass
MOSFET when the input-output voltage differential is at
its highest.
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3601.2008.07.1.1