XC9220/XC9221
Series
■OPERATIONAL
EXPLANATION (Continued)
●
Setting of Coil Value
Recommended inductance value of coil by oscillation frequency is shown in the chart below.
FOSC (kHz)
300
500
1000
L (μH)
22.0
10.0
4.7
However, the more current change in each pulse becomes larger, the more output ripple voltage becomes
higher when dropout voltage is high. This may lead to instability. In this case,
increasing the coil
inductance value will make Ipk_AC small, and it makes output stable.
Ipk_AC = (V
IN
– V
OUT
) x V
OUT
/ (V
IN
x L x FOSC)
L: Coil inductance value
FOSC: Oscillation frequency
Please do not exceed the coil rating. Coil peak current is determined by the following equation.
Ipk = I
OUT
+ Ipk_AC / 2
10/22
TOREX [ TOREX SEMICONDUCTOR ]
