buenos
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hi
I designed a digital board with 2 main DCDC converters: 3.3V and 5V. They are working from a 20V adapter input or from a 16V battery pack.
If i use a battery pack, both DCDCs are producing a few 100 Hz noise, instead of a DC level. From the adapter input, they work fine.
In the case of the battery, if i measure the DCDC input voltage by oscilloscope, its DC, nut jumping. Only the DCDC outputs are jumping.
Why?
The 2 DCDCs: TPS40057, LM3489MM. the system power selector is with the ISL6255 battery charger.
I designed a digital board with 2 main DCDC converters: 3.3V and 5V. They are working from a 20V adapter input or from a 16V battery pack.
If i use a battery pack, both DCDCs are producing a few 100 Hz noise, instead of a DC level. From the adapter input, they work fine.
In the case of the battery, if i measure the DCDC input voltage by oscilloscope, its DC, nut jumping. Only the DCDC outputs are jumping.
Why?
The 2 DCDCs: TPS40057, LM3489MM. the system power selector is with the ISL6255 battery charger.