TPS61170: TPS61170 doesn't work.

Emilija Zukauskaite

Part Number: TPS61170

Hi,

I'm having issues with TPS61170 design. First of all, it wasn't boosting the voltage to 12V. I replaced the diode and now its boosting but not in a right way. It gives 10V output instead of 12V. And the diode voltage drop is 10V - Vin! I don't really understand why. For example, I apply 8V, then I get 2V voltage across the diode. If I apply 7V, I get 3V across the diode. I replaced the IC and it is doing the same thing. Please help me!

I connected CTRL pin to VIN.

Thank you.

Emilija

over 6 years ago

0 Helen chen over 6 years ago

TI__Mastermind 40080 points

Dear Sir,

The upper side resistor is of wrong value. it should be 87.6k ohm.

0 Emilija Zukauskaite over 6 years ago in reply to Helen chen

Expert 1100 points

Dear Helen,

Yes, sorry I mixed up the designs. I meant to provide 10V with this design so it is correct.

What about the diode drop? Is it normal to have Vout-Vin drop across the diode?

Thank you.

Regards,
Emilija

0 Emilija Zukauskaite over 6 years ago in reply to Emilija Zukauskaite

Expert 1100 points

Dear Helen,

I tested the design and I get only 77% efficiency instead of 85% simulated.
I used 3.5Vin and I get 10V out at 0.1A.
I use SRN5040TA-220M inductor with low DC resistance of 123mohms. The simulation uses SDR0302-220ML which has 660 mohm resistance.
I use MBR0530T1G schttky diode with a similar voltage drop of 0.39V.
Do you have any ideas why the efficiency would be lower?

Thank you.

Regards,
Emilija

0 Jasper Li over 6 years ago in reply to Emilija Zukauskaite

TI__Mastermind 46905 points

Hi Emilija,
1. could you share the layout?
2. could you measure the VIN, VOUT waveform to check if the IC is stable.

0 Helen chen over 6 years ago in reply to Emilija Zukauskaite

TI__Mastermind 40080 points

Dear Sir,

How do you measure the efficiency? Did you measure the Vin and Vout on the board? because if the input trace is long, there will be voltage drop across the cable and results in low efficiency.

0 Emilija Zukauskaite over 6 years ago in reply to Jasper Li

Expert 1100 points

Hi Jasper,

Please see the layout attached. I will measure the waveforms next week as I dont have an access to oscilloscope.

Thank you.

0 Emilija Zukauskaite over 6 years ago in reply to Helen chen

Expert 1100 points

Hi Helen,

I measured Vin from the power supply and Vout on the board. And I measure the input and output current using the same multimeter. I found that I was using a resistor to simulate the load which was low power. It was getting hot and the resistance slightly dropped. I ordered new resistors with a correct power rating, so I can test it properly. Is there anything else I can do meanwhile?

Thank you.
Regards,
Emilija

0 Helen chen over 6 years ago in reply to Emilija Zukauskaite

TI__Mastermind 40080 points

Hi Emilija,

Thanks for the update! Please meaure Vin on the board next time after get the new load.

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TPS61170: TPS61170 doesn't work.