XC9502 Series
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NoteS on Use
2ch. Step-up / down DC/DC Controller ICs
1. Checking for Intermittent Oscillation
The XC9502 series is subject to intermittent oscillation in the proximity of the maximum duty if the step-down ratio is low (e.g.,
from 4.2 V to 3.3 V) or a heavy load is applied where the duty ratio becomes high. Check waveforms at EXT under your operating
conditions. A remedy for this problem is to raise the inductance of coil L or increase the load capacitance CL.
2. PWM/PFM Automatic Switching
If PWM/PFM automatic switching control is selected and the step-up ration is low (e.g., from 4.5V to 5.0V) or the step-down ratio is
high (e.g., from 10.0V to 1.0 V), the control mode remains in PFM setting in the whole load range, since the duty ratio under
continuous-duty condition is smaller than the PFM duty ratio of the XC9502 series. The output voltage's ripple voltage becomes
substantially high under heavy load conditions, with the XC9502 series appearing to be producing an abnormal oscillation. If this
operation becomes a concern, set pins PWM1 and PWM2 to High to set the control mode to PWM setting. For use under the
above-mentioned condition, measured data of PWM/PFM automatic switching control shown on the data sheets are available up
to IOUT = 100 mA.
3. Ratings
Use the XC9502 series and peripheral components within the limits of their ratings.
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TOREX [ TOREX SEMICONDUCTOR ]
