A7986A DC-DC Design not working

[martinpetkovic]

Posted on April 26, 2016 at 13:07

Hi to all,

please help!!I made a DC-DC converter from 9-30V input and 5V output. You can find in the attachment a pdf print from the eDesign Suite.The Cin that I'm using is: C1210C335K5RACTUThe L is: B82477G4153MThe Cout is: LMK325BJ476MM-POn pin 2 I'm getting pulses with around 500kHz which is OK.But, the waveform that I'm getting on pin 1, which is also attached, has additional pulses that are strange to me.For output currents greater than 1.5A the power supply is not working. The output voltage drops to around 4V and it is unstable.I run out of ideas, please tell me your thoughts.  #a7986a

[martinpetkovic]

Posted on April 26, 2016 at 15:09

Additional info.

In the attachment are additional 3 waveforms where the circuit performed ''good'' and bad. ________________ Attachments : Uin_16V_Uout_5V_Iout_2A_-_OK.jpg : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006Htzf&d=%2Fa%2F0X0000000ab7%2FF7HBPA7TGLi1IhJ7wtQj2xCWvXvKVczq4jQDxIWQs1I&asPdf=falseUin_30V_Uout_2.2V_Iout_1.5A_-_Not_OK.jpg : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006Htq5&d=%2Fa%2F0X0000000aXa%2FZjgmUIq5vi4HSRRLppge8VrBcBZ1Qzlq9AgYykSAFJE&asPdf=falseUin_30V_Uout_5V_Iout_1.2A_-_OK.jpg : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006Htq6&d=%2Fa%2F0X0000000aXb%2Fe.bMzS0Pq5CTNWa3JsD7ylr7IUdqFbrJL2FRc4WC2Ao&asPdf=false