AAT3698 Datasheet, PDF (17/21 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
Charger Output Capacitor (BAT)
The AAT3698-1/-2 only requires a 1μF ceramic capacitor
on the BAT pin to maintain circuit stability. This value
should be increased to 10μF or more if the battery con-
nection is made at any distance from the charger output.
If the AAT3698-1/-2 is used in applications where the
battery can be removed from the charger, such as desk-
top charging cradles, an output capacitor greater than
10μF may be required to prevent the device from cycling
on and off when no battery is present.
Linear Regulator Output Capacitor (LDOOUT)
For proper load voltage regulation and operational stabil-
ity, a capacitor is required between LDOOUT and GND.
The output capacitor connection to the LDO regulator
ground pin should be made as directly as practically pos-
sible for maximum device performance. Since the regu-
lator has been designed to function with very low ESR
capacitors, multilayer ceramic capacitors in the 1.0μF to
10μF range are recommended for best performance.
Applications utilizing the exceptionally low output noise
and optimum power supply ripple rejection of the
AAT3698-1/-2 should use a value of 2.2μF or greater for
the LDO’s output capacitor.
Printed Circuit Board
Layout Recommendations
For proper thermal management and to take advantage
of the low R_DS(ON) of the AAT3698-1/-2, a few circuit
board layout rules should be followed: IN and BAT should
be routed using wider than normal traces, and GND
should be connected to a ground plane. To maximize
package thermal dissipation and power handling capac-
ity of the AAT3698-1/-2 TDFN33-14 package, solder the
exposed paddle of the IC to the thermal landing of the
PCB, where the thermal landing is connected to the
ground plane. If heat is still an issue, multi-layer boards
with dedicated ground planes are recommended. Also,
adding more thermal via holes on the thermal landing
would help transfer heat to the PCB effectively.
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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