APL3208A データシートの表示（PDF） - Anpec Electronics
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APL3208A Datasheet PDF : 17 Pages
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APL3208A/B/C
Application Information
RBAT Selection
Connect the VBAT pin to the positive terminal of battery
through a resistor R for battery OVP function. The R
BAT
BAT
limits the current flowing from VBAT to battery in case of
VBAT pin is shortened to ACIN pin under a failure mode.
The
recommended
value
of
R
BAT
is
200kΩ.
In
the
worse
case of an IC failure, the current flowing from the VBAT
pin to the battery is:
(30V-3V)/ 200kΩ =135µA
where the 30V is the maximum ACIN voltage and the 3V
is the minimum battery voltage. The current is so small
and can be absorbed by the charger system.
Capacitor Selection
The input capacitor is for decoupling and prevents the
input voltage from overshooting to dangerous levels. In
the AC adapter hot plug-in applications or load current
step-down transient, the input voltage has a transient
spike due to the parasitic inductance of the input cable. A
50V, X7R, dielectric ceramic capacitor with a value be-
tween 1µF and 4.7µF placed close to the ACIN pin is
recommended.
The output capacitor of CHG_DET is for CHG_DET volt-
age decoupling. And also can be as the input capacitor of
the charging circuit. At least, a 1µF, 10V, X7R capacitor is
recommended.
Layout Consideration
In some failure modes, a high voltage may be applied to
the device. Make sure the clearance constraint of the PCB
layout must satisfy the design rule for high voltage. The
exposed pad of the TDFN2x2-8 performs the function of
channeling heat away. It is recommended that connect
the exposed pad to a large copper ground plane on the
backside of the circuit board through several thermal vias
to improve heat dissipation. The input and output capaci-
tors should be placed close to the IC. The high current
traces like input trace and output trace must be wide and
short.
Copyright © ANPEC Electronics Corp.
11
Rev. A.2 - Nov., 2009
www.anpec.com.tw
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