DC-DC Circuit Calculator

Input voltage v Output voltage v Output current ma Output voltage ripple factor the mv (pp) and Operating frequency khz

1: The polarity reversal. 2: Boost. 3: The step-down. Three typical circuit, the automatic calculation of the external components parameters
to use: enter the parameters you want in the left central box, then click the "schematic" button to calculate and refresh it automatically to all relevant external components parameters and the corresponding standard circuit drawings, the design of dc-dc circuit of intelligent and efficient.
Warning: If you enter the parameters of more than 34,063 the limit, it will automatically pop up a warning window to remind you to change them.
Special input : To design a polarity reversal circuit with a negative sign in front of the numbers of input or output voltage, for example,-5v.

This is a dc-dc power conversion IC, the application is relatively broad, generic cheap and easy to purchase. Polarity inversion efficiency up to 65%, boost efficiency up to 90% step-down efficiency up to 80%, conversion efficiency and operating frequency is proportional to the filter capacitor.

In addition, the output power is mainly, such as> 250 ~ 300ma through external expansion of the power tube to expand the current bipolar or mos-type expansion flow tube can be formula and other parameters and their meaning in detail See the lowest part of the details can be.

External components nominal meaning and value of the formula:

Vout (output voltage) = 1.25V (1 + of R1/R2)

Ct ( timing capacitor ) : determine the internal operating frequency. Ct = 0.000 004 * Ton, (operating frequency)

Ipk = 2 * Iomax * T / toff

Rsc ( limited to flow resistance): determine the output current. Rsc = 0.33/Ipk

Lmin ( inductance): Lmin = (Vimin-Vces) * Ton / Ipk

Co (filter capacitors): Determine the output voltage ripple factor, Co = Io * ton / Vp-p (ripple factor)

Fixed value parameters:

Vces = 1.0V ton / toff = (Vo + Vf-Vimin) / (Vimin-Vces) Vimin: instability in the input voltage when the minimum

Vf = 1.2V fast switching diode forward voltage drop

Other manuals parameters:

Attention in practical applications:

1: fast switching diode can choose IN4148, occasions that require high efficiency must be used or IN5819

The 2:34063 able to withstand the voltage, that is, enter the absolute value of the output voltage can not exceed 40V, or can not secure and stable.