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hewittalec
Level 1
Level 1
5 sign-ins First reply posted First question asked

Hi There,

 

I am using the 6EDL7141 IC in a BLDC design. I intend to use the internally generated 3.3V DVDD to power an MCU on the same board.

My problem is that the IC seems to begin generating the DVDD voltage on power up, but it quickly shuts off. I am not sure if the whole chip is going into shutdown mode, or just the regulator section. After DVDD shuts off with the bus voltage still applied, the IC continues to consume power. The duration of DVDD shutdown appears to be between 200ms and 2 seconds.

Also note that the DVDD ripple at 3.3V is considerable.

I will attach schematic and scope shot of DVDD during power up.

Please note on schematic that all grounds are tied together.

Any help is much appreciated. Thanks,

Alec

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1 Solution
Xiangrui
Moderator
Moderator
Moderator
500 replies posted 250 solutions authored 50 likes received

Hi,

I know it's not about hall sensor. If your MCU can be supplied with current under 200mA, then test it with following steps.

Firstly, try to change C13 to 4.7uF, C3 to 10uF. Small Capacitors can lead to a unstable power supply.

Then if it doesn't work. Please upload the circuit of MCU Pins and try to read out the fault register in 6EDL7141 to check if under voltage lock of DVDD happens.

BR,

Xiangrui 

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5 Replies
Xiangrui
Moderator
Moderator
Moderator
500 replies posted 250 solutions authored 50 likes received

Hi, Alec

Linear Regulator DVDD may have not enough supply capability to drive a MCU.

Please check how high the current does your MCU need.

Linear Regulator DVDD has maximal 300mA output current.

BR,

Xiangrui

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Vinay
Moderator
Moderator
Moderator
50 solutions authored 100 replies posted 250 sign-ins

Hello @hewittalec,

Good Day!

Thanks for posting your question in Infineon community and sorry for the inconvenience caused.

 

This might be issue with the loading of 6EDL7141 with MCU and hall sensor signals. As MCU, hall sensor signals are connected to DVDD, please kindly check DVDD_OCP threshold.

 

Kindly check the output of the LDO at the 6EDL7141 and at load (MCU) and if required add some capacitors at the load DVDD pin.

 

Please refer this thread Really bad DVDD ripple voltage when EN_DRV is pulled HIGH on 6EDL7141

 

Thank you!

 

Best Regards,
Vinay
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hewittalec
Level 1
Level 1
5 sign-ins First reply posted First question asked

Hi, thank you.

 

I do NOT have hall sensors. When I power DVDD externally, the total power consumption of the rest of the components not including the 6EDL7141 is 41mA @ 3.3V maximum.

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Xiangrui
Moderator
Moderator
Moderator
500 replies posted 250 solutions authored 50 likes received

Hi,

I know it's not about hall sensor. If your MCU can be supplied with current under 200mA, then test it with following steps.

Firstly, try to change C13 to 4.7uF, C3 to 10uF. Small Capacitors can lead to a unstable power supply.

Then if it doesn't work. Please upload the circuit of MCU Pins and try to read out the fault register in 6EDL7141 to check if under voltage lock of DVDD happens.

BR,

Xiangrui 

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Xiangrui, thank you.

Adding DVDD capacitance in fact solved the problem.

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