AP6714 Datasheet, PDF (12/15 Pages) Diodes Incorporated – 1.8MHz SYNCHRONOUS BOOST CONVERTER

AP6714
1.8MHz SYNCHRONOUS BOOST CONVERTER
Typical Operating Characteristics (Continued)
Power On Wave
Power On Wave
Figure. 27
Figure. 28
Application Information
„ Input Capacitor Selection
The input filter capacitor reduces peak currents drawn from the input source and reduces input switching
noise .In most applications a 10uF is recommended.
„ Output Capacitor Selection
The major parameter necessary to define the output capacitor is the maximum allowed output voltage ripple
of the converter. This ripple os determined by two parameters of the capacitor, the capacitance and the ESR
(Equivalent Series Resistance). It is possible to calculate the minimum capacitance needed for the defined
ripple, supposing that ESR is zero, by using Equation below:
C _MIN
=
I _OUT × (V_OUT − V_IN )
f × ΔV ×V_OUT
where
f =the switching frequency
△V =the maximum allowed ripple
„ Shutdown Mode
The AP6714 converter will stop switching by setting EN pin Low, and is turned on by pulling it high. If this
feature is not used, the EN pin should be tied to VCC pin to keep the regulator output on all the time. To
ensure proper operation, the signal source used to drive the EN pin must be able to swing above and below
the specified turn-on/off voltage thresholds listed in the Electrical Characteristics section under VIL and VIH.
AP6714 Rev. 4
12 of 15
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FEBRUARY 2009
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