AP6714

1.8MHz SYNCHRONOUS BOOST CONVERTER

AP6714 Rev. 4

12 of 15

FEBRUARY 2009

www.diodes.com

Power On Wave

Power On Wave

Figure. 27

Figure. 28

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:

OUT

IN

OUT

OUT

MIN

V

V

f

V

V

I

C

×

Δ

×

−

×

=

)

(

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

Typical Operating Characteristics

(Continued)

Application Information