! NoteS on Use

1. Checking for Intermittent Oscillation

2. PWM/PFM Automatic Switching

3. Ratings

Use the XC9502 series and peripheral components within the limits of their ratings.

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.

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.

XC9502 Series

2ch. Step-up / down DC/DC Controller ICs

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