WEBENCH® Tools/TLV61046A: TLV61046A

Hi Hanh:

May you help to catch the waveform of Vin, Vou, SW, and better with Icoil? We could do better analysis with details information. 

Hi Minqiu

Thanks for your reply

I have a some picture of the Vout and SW waveform can send immediately now

Best Regards !

Hi Hanh:

According to the waveform of SW pin, the load or the loop is not stable.

Please confirm the load condition. Is it easy to replace the OLED with a constant resistance with about 50ma load？

If the issue is still exist, please share the information/part number about the inductance and Cin, Cout. Thanks for your understanding~

Hi Minqiu !

26 Jul 2019 16:28:52 of the piture is Vout of waveform, if i add big Capacitor at Vout Pin, waveform will nice however whistles from the inductor still comming out.

Best Regards !

Hi Minqiu:

Yes, That it is,with a constant resistance ( resistor) the isssue is not exist.

OLED Load is not stable But it must use in my project, what should i do in this case?

 Best Regards !

Hi Minqiu:

Cout of value is 22uF/25V, i tried with Cout 1000uF/35V and the isssue is exist.

proper inductance of value is 10uH/1A

layout as the picture of attachment

Best Regards !

Hi Minqiu:

With OLED load ( load is unstable ) are there any other replacement parts ?

Best Regards !

Hi Minqiu

I press the wrong "resolved" button, but i am still wait your reponse

Best Regards !

Hi Hanh:

May you catch the waveform with 1000uf cap? For SW pin and Vout. the time Axis could be around 10us -50us /div

Hi Minqiu:

This is waveform with 1000uF capacitor add in Vout ( chanel 1 - yellow)

Best Regards !

Hi Minqiu:

This is SW of waveform with 1000uF Cout.

Best Regards !

Hi Nanh:

It seems the Vout is stable, and the noise is caused by OLED intermittent working. May you add a waveform for Vout with AC coupled to ensure Vout is stable?

 I'll recommend you to see TPS61086 with Force PWM mode. The converter will keep switch and the frequency will be stable. 

http://www.ti.com/lit/ds/symlink/tps61086.pdf

Hi Minqiu:

AC coupled of waveform is stable. Because TPS61086 with Vin 2.3 to 6.0V  , it can not be used in my project. My project use 2.0 - 3.5V of power supply.

Is there any other way with TLV61046A? Does that whistles affect component life?

Best Regards !

Hi Hanh:

It's hard to modify it based on the TLV61046A, as TLV61046 has the PFM mode inside.

According to your waveform, there is large switch noisy. You could add a small cap close to the Vout PIN and GND. It may do some help.

Hi Minqiu:

Thanks for your help, i will try to do so

Best Reagards !

Hi Hanh:

Long time no see. Is there any updating? 

Hi Minqiu:

I am still trying to do that. When i use Larger capacitor for input and output, the whistle was smaller but still exist, i will try with larger inductor.

Thanks for your help

Best  Regards !

Hi Minqiu:

The sound a little smaller but still exist, i am using Cin 15uF,ESR 3Ohm. Cout 22uF, ESR 60mOhm. L 10uH  168mOhm 1.26A. Perhaps there  no way to stop this sound

Best Regards !

Hi Hanh:

Thanks for your updating. It's glad to see the noise is smaller. It's really hard to make the system stable with unstable load.

Have you tried to added a small capacitance (1uf or 100nf) to make the close loop from Vou, Cout, GND as short as possible? It may do some help.

Hi Minqiu:

Your recommend to use TPS61086, can i receive sample ?

Best Regards !

Hi Hanh:

You could check if the sample is available in TI.com.

And I will invite the expert for TPS61086 to check if it could avoid the noise for your application. Thanks for your patience.

Hi Hanh:

The TPS61086 has the FPWM mode, but the min Vin is 2.3V. May couldn't cover the whole input voltage range.

Besides, what's the type of your inductance? The noise may be smaller if you choose an integrated inductance.

Hi Minqiu:

The test of results today ,screech of OLED is also exist. screech of coil becomes not disturbing

Thanks for your help

Best Regards !