EP3003 Datasheet, PDF (10/12 Pages) Eorex Corporation – 2-CH, 600mA Synchronous Step-down Converter

EP3003
Input Capacitor Selection
The input capacitor reduces the surge current drawn from the input and switching noise from the device.
The input capacitor impedance at the switching frequency shall be less than input source impedance to
prevent high frequency switching current passing to the input. A low ESR input capacitor sized for
maximum RMS current must be used. Ceramic capacitors with X5R or X7R dielectrics are highly
recommended because of their low ESR and small temperature coefficients. A 10µF ceramic capacitor
for most applications is sufficient.
Output Capacitor Selection
The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop
stability. The output capacitor must have low impedance at the switching frequency. Ceramic capacitors
with X5R or X7R dielectrics are recommended due to their low ESR and minimization of large
temperature and voltage coefficients. The output ripple ΔV_OUT is determined by:
( ) _ΔVOUT
≤ ^{VOUT × VIN − VOUT}
V_IN × f_OSC × L
× _{⎜⎜⎝⎛}
ESR
+
8×
1
f _OSC
× C3 ^{⎟⎟⎠⎞}
Rev.01
10