TIDA-01505: The Q8 design technical problem, And U4 peripheral device parameters

Tommy

Part Number: TIDA-01505

In the schematic of TIDA-01505:

1、Why use Q8(DXT2222A-13) for the UCC28C43QDRQ1? AND does it necessary to use SOT-89 package?

2、When we design a new application. How should we design the peripheral parameters of U4(TL431AQDBZRQ1), such as R70 & C68 & C71 in the image below:

0 Xun over 3 years ago

Hi Tommy,

For 1): Q8 is to add lead edge blanking feature, this is optional, you can remove this circuit

2): Yes, R70 & C68 & C71 are needed to add compensation network and making the converter stable.

0 Tommy over 3 years ago in reply to Xun

Thanks for your answer.

about the R70 & C68 & C71 selection, Is there a reference formula to help design?

0 Xun over 3 years ago in reply to Tommy

Hi Tommy,

The compensation is usually done and adjusted through bode plot measurement. For estimation please refer to the design guide page 17.

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