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LTC4057 Datasheet, PDF (10/12 Pages) Linear Technology – Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT
LTC4057- 4.2
APPLICATIO S I FOR ATIO
VCC Bypass Capacitor
Many types of capacitors can be used for input bypassing;
however, caution must be exercised when using multi-
layer ceramic capacitors. Because of the self resonant and
high Q characteristics of some types of ceramic capaci-
tors, high voltage transients can be generated under some
start-up conditions, such as connecting the charger input
to a live power source. Adding a 1.5Ω resistor in series
with an X5R ceramic capacitor will minimize start-up
voltage transients. For more information, refer to Applica-
tion Note 88.
Charge Current Soft-Start
The LTC4057 includes a soft-start circuit to minimize the
inrush current at the start of a charge cycle. When charg-
ing begins, the charge current ramps from zero to the full-
scale current over a period of approximately 100µs. This
has the effect of minimizing the transient current load on
the power supply during startup.
4057f
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