TLV61220： TLV61220 output problem(Iout 20ma+)

Hi Daohai,

please share the waveform of the VIN, SW and VOUT at VOUT=4V condition.

HI，this is PCB。Design 1 Reference tlv61220_PDF, Design 2 Reference EVM。

waveform should tomorrow.

thx..20191117.zip

HI,this is waveform .

Should I replace the all package with 0603 and re-layout pcb?  be better when the components are closer?

thx..

thx..

Hi Daohai,

the layout is not bad. the behavior is strange. 

did you observe the behavior in several board? all the board have the same performance, correct?

HI, i re-layout again and change the package(0603),Components are getting closer. i think it's better,but My boss is not satisfied with the efficiency of the power supply（@High Current）.

The PIN_SW   Frequency is 1M, and stable.

THIS is Results(about 3 test board),can i get better ?

should i change cap(TAN)  or inductance?

Hi Daohui,

what is current rating and DCR of the inductor?

did you measure the input voltage closed to the input pin of the IC? 

from the datasheet, the efficiency >90%

HI, the inductor,i din't change cap(TAN), the TAN is baddly than X5R on my PCB

yeah,very close with IC's PIN,both VIN and VOUT ,

but never mind ,my boss say ok...so, it's end...XD

Thanks for your help, but I still want to know where I am doing badly.

Hi Daohai,

the inductor is OK.

and the output capacitor must be ceramic capacitor, instead of TAN cap.

it is strange that the efficiency is only 80%. I'm not sure it is caused by the measurement method or the system board.

could you try to measure the efficiency in several boards?

HI,

I tested 4 boards, all of which are only 80% efficient(in high current).

the board layout by me(Reference tlv61220's pdf) ,not official EVM board.

Hi Daohai,

the data is strange as the efficiency should be closed the data in the datasheet.

I would you apply an EVM in TI.COM for reference? measure the efficiency with the EVM to check if the issue is caused by the bench setup.

HI, this is my layout, one of layout is reference EVM board,but efficiency is only 80% too.

i can't provide any more data.

is matter of PCB material??

i have no idea...TLV61220DBVR EVM20191118.zip

Hi Daohai,

it is low possibility that the issue is caused but PCB material. could you apply an EVM for reference, to check if the issue is caused by the board or measurement method.

Hi Daohai,

i found two layout in the files, which one is the correct?

Both correct, left is reference EVM ,right is reference 61220's pdf.

HI , It's tools and 3.7V lithium battery

Hi Daohai,

i'm not sure about the meaning, the left layout is not closed to the TLV61022EVM layout.there is no via between the COUT ground and IC ground pin in the TLV61220EVM layout

HI, right is tlv61220 EVM board

left is this ,another EVM board..am i wrong?

Hi Daohai,

it is not TLV61220EVM. I would suggest using the right comer layout in your board.

the output capacitor must be ceramic capacitor, not tan capacitor. 

how did you measure the input current when measuring the efficiency.