AAT3698 Datasheet, PDF (13/21 Pages) Skyworks Solutions Inc. – 1.6A Linear Li-Ion Battery Charger in a 3x3 TDFN Package

DATA SHEET
AAT3698
1.6A Linear Li-Ion Battery Charger in a 3x3 TDFN Package
POK = high
Power Fail
STAT = POK = high
POK = low
Charger Off
STAT = high,
POK = low
Any States
EN = high or V_IN ≤ V_BAT or V_BOVP ≤ V_BAT
EN = low & V_IN ≥ V_BAT ≤ V_BOVP
Pre-Charge
STAT = POK = low
Charge Complete
STAT = high, POK = low
Charge Off for AAT3698-1
Charge On for AAT3698-2
V_BAT < V_MIN V_BAT ≥ V_MIN
V_BAT < V_RCH
(AAT3698-1 only)
I_BAT = I_TERM
Fast Charge
STAT = POK = low
V_BAT ≥ V_CO(REG)
Voltage Mode
Charge
STAT = POK = low
T_LOOP
T_LOOP
Figure 2: Charger Operational State Diagram.
Charge Status Output
The AAT3698-1/-2 provides battery charging status via
the charge status indication pin (STAT). This pin is inter-
nally connected to an N-channel open-drain MOSFET,
which can be used as a logic signal or to drive an exter-
nal LED. The STAT pin pulls high to indicate charge
completion. The charge completion occurs only when the
EN pin is pulled high or the charge current reaches its
charge termination current level. The status pin indicates
the conditions as described in Table 1.
Charge Status
V_IN > V_UVLO
V_IN > V_OVP
The charge current is below its termination level
EN pin is pulled high
Battery is charging and the charge current is above
its termination level.
STAT
High
High
High
High
Low
Table 1: LED Status Indicator.
Enable / Disable
The AAT3698-1/-2 provides an enable function to turn the
charger IC on and off. The enable (EN) pin is internally
pulled down with 200kΩ. When EN is pulled down or left
floating, the device begins normal operation. When EN is
pulled to a logic high level, the AAT3698-1/-2's charging
circuit will be shut down and forced into sleep state. The
over-voltage protection/LDO circuit remains active even
in sleep state. In sleep state, charging is halted regardless
of the battery voltage or charging state. When the device
is re-enabled, the charge control circuit automatically
resets and resumes charging functions with the appropri-
ate charging mode based on the battery charge state and
measured cell voltage at the BAT pin.
Under-Voltage Lockout (UVLO)
The AAT3698-1/-2 has a typical under-voltage lockout
threshold of 3V. When the input voltage is less than the
UVLO level, OVP and the charger are turned off. The
UVLO is designed with 150mV hysteresis to ensure circuit
stability.
Over-Voltage Protection
In normal operation, the OVP protection device acts as a
load switch, connecting the power source from IN to
INCHR. This switch is designed with very low resistance
to minimize the voltage drop between the power source
and the charger and to reduce the power dissipation.
When the voltage on the power source exceeds the OVP
trip point, V_OVP, the switch immediately turns off and dis-
connects the load and the charger from the power source
and preventing damage to any downstream components.
Simultaneously, the fault flag is raised, alerting the sys-
tem. If an over-voltage condition is applied at the time of
the device enable, the switch remains open (OFF).
Power OK Output Flag
The Power OK flag (POK) is an active-low open-drain
power good reporting output. A pull-up resistor should
be connected from POK to another system power volt-
age. In the event of an under-voltage or over-voltage
condition, POK will be de-asserted. After the over-volt-
age fault is released, POK will be asserted. POK will be
also de-asserted when V_IN is lower than V_BAT when
EN is low. When EN is high, POK is asserted only after
UVLO and OVP conditions.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
201902B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 27, 2012
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