TPS63020: output have a step

Betty Guo

Part Number: TPS63020

Hi,

customer schematic as below. C41,C45,C44 is NC, input is 5V, output IS 5V/2A.

Here is the test summary

1. remove C42, connect PS and VINA, use NPN to control EN, found the output have a step, the voltage of step is about 2.28V

2. PlaceC42, connect PS and VINA, use NPN to control EN, found the output will ring at 2.2V

3. place C42, connect PS,EN and VINA,the output is normal, not step.

waveforms:

1. Blue is EN , Yellow is output

Why the ouput have a step when use NPN control EN pin? how to reduce this?thank you

over 3 years ago

0 Jasper Li over 3 years ago

TI__Mastermind 46905 points

Hi Betty,

did you measure the input voltage waveform? i'm thinking if the UVLO is triggered.

0 Betty Guo over 3 years ago in reply to Jasper Li

TI__Expert 7300 points

Jasper,

input voltage doesn't trigger the UVLO,below yellow is input voltage,green is output

0 Jasper Li over 3 years ago in reply to Betty Guo

TI__Mastermind 46905 points

Betty,

the step period is actually right at the UVLO region. could you delay the EN signal? only enable the IC when the VIN voltage is ready.

0 Betty Guo over 3 years ago in reply to Jasper Li

TI__Expert 7300 points

Hi Jasper,

one more question, I see the UVLO threhhold is 1.5V in VINA pin. Can we connect the VINA pin to supply voltage, connect and control the EN and PS together?

and, as the summary 2 in the first post, why place the C42, device can't work?

thanks

0 Jasper Li over 3 years ago in reply to Betty Guo

TI__Mastermind 46905 points

hi Betty,

the VINA need a stable voltage, i would not suggest connecting the VINA to supply voltage directly.

did you measure measure the voltage level at every pins to check if the voltage is OK?

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TPS63020: output have a step