TPS51225B output is 5V and 3.3V, Vin is 8V,the output is right . but Vin is less than 8V ,such as 7V, the output is less than 5V ,3.3V is right. I read the data sheet Vin range is 5.5~24 . Why the output isn't 5V when the Vin less than 8V?
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TPS51225B output is 5V and 3.3V, Vin is 8V,the output is right . but Vin is less than 8V ,such as 7V, the output is less than 5V ,3.3V is right. I read the data sheet Vin range is 5.5~24 . Why the output isn't 5V when the Vin less than 8V?
Hello,
7Vin/5Vout should be OK, Need you provide more information to review.
When Vin>8V, 5Vout=? When Vout<8V, 5Vout=? and What's the loading value for 5Vout?
Please upload schematic for review.
Hi,
Most of Schematic looks OK, BUT for output cap of both 3.3V/5V, I found there were only MLCC 22uf/10uf cap, no E-cap or pos-cap, right? if so it may cause Loop unstable, because there is some requirement for output cap ESR/cout for 51225, please refer to Equation2 in DS, So I just suspect this cause the Vout abnormal, and I suggest you to change 10UF MLCC to 1pcs E-cap or pos-cap to re-check.
By the way, whether the 5Vout can be OK with no loading? and Please catch SW and Vout, Vin waveform before and after change ouput cap, waiting for your check result...
Finally, just by the way, better also change 3.3V output cap to pos-cap to make sure loop stable.
Good to hear your result, This question can be closed now.