UCC28C41: Flybuck System cannot boot，the occasional failure

wen guangcai

Part Number: UCC28C41

UCC28C41 use in Flybuck System, Schematic Design VCC input voltage 12V, VCC input resistance 4.7K,The phenomenon is as follows:
1、When UCC28C41 cannot boot,VCC input voltage measure is 1.53V;

2、When short input resistance 4.7K,Flybuck System recover and start;

3、After successful startup, it rarely appears subsequently;

4、we use mosfet Qg is 62 nC;

We need your help to provide a solution, thank you.

2 个月前

0 Eirwen 2 个月前

TI__Mastermind 29835 points

已经收到了您的案例，调查需要些时间，感谢您的耐心等待。

0 wen guangcai 2 个月前回复 Eirwen

Prodigy 10 points

这个是部分原理图，希望对问题分析有所帮助；

0 Eirwen 1 个月前回复 wen guangcai

TI__Mastermind 29835 points

您能否发送剩余的电路？（可以通过站内私信发送）

0 wen guangcai 1 个月前回复 Eirwen

Prodigy 10 points

请问如何通过站内私信发送，我花了一些时间尝试了几回，无法找到站内私信发送

0 Eirwen 1 个月前回复 wen guangcai

TI__Mastermind 29835 points

您看下页面左上角的未读消息，我给您发了私信

0 wen guangcai 1 个月前回复 Eirwen

Prodigy 10 points

我把相关资料通过私信发送给您了

0 Eirwen 1 个月前回复 wen guangcai

TI__Mastermind 29835 points

The issue is likely showing up because the startup resistor cannot provide enough current for the UCC2841 device to remain on when the UVLO turn-on threshold is reached.

Since this application is just a 12-V input fly-buck, there is no need to have a start-up resistor; this resistor can be removed and replaced by a short or zero-ohm resistor. The VDD pin can be connected directly to the input voltage of 12V with no startup resistor.

The start-up resistor is traditionally added for applications with a high input voltage where a small amount of current turns-on the controller and then the controller depends on auxiliary winding for receiving power in steady-state.

0 wen guangcai 1 个月前回复 Eirwen

Prodigy 10 points

谢谢，您的回答给我很大帮助；

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UCC28C41: Flybuck System cannot boot，the occasional failure