TPS65100: TPS65100 custom EVK not working

Hi Customer,

Our expert is currently out of office. He will reply to you next Monday. Thanks for your understanding.

Best Regards,

Steven

Hi DGR,

Do you have the start-up waveform of VIN, SW and VOUT1 with the oscilloscope?

BR

Patrick

During startup the SW pin Goes to 3.3V Without generating any waveform and VIN Remains stable at 3.3 and Vout1 at 3.3v Respectively.
Could you suggest me how to start the TPS65100 with only VOUT1 Enabled so we can check the main switcher.

Hi DGR,

OK, could you please also monitor REF and COMP voltage during the start-up? And have you connected EN and ENR to VIN?

BR

Patrick

Image Showing Waveform at the SW pin

Image Showing AC Component at the Vout 1 (Main Boost Convertor)

Image Showing DC Component at VOUT 1




Hi Patrick,

                I can see that the switching is taking place at the SW pin. Please check the waveform as I am not getting output from the Vout 2,Vout 3 Pins and Vout 4 Is only producing -2.2v

VOUT1=     9.632
VCOMIN =  3.363

VOUT2= -2.23V

VOUT3= 1.02mV

VOUT4= 1.74V

Hi DGR,

Have you confirmed the SW waveform is correct? If the VOUT1=9.6V, the SW voltage should not be that small.

BR

Patrick

So I have changed couple of things to make this board work.
C2-/mode was shorted to ground so I have removed it from there and connected the cap directly to pin 15 and 14
Now I am getting the following readings-

REF =1.65V

Vout 1= 9.62V (connected 35 Ohms Resistance as load)

Vout 2= -3.54V

Vout 3= 460 mV

VCOMIN = 1.72 V

Wave for at SW pin is attached

Hi DGR,

Ok, so could you please upload your latest schematic? Thanks

BR

Patrick

Schematic is same, I have just changed the Filter capacitors and Added a 35ohm Load at the VOUT 1Output and removed the c2-/mode pin connected to ground. Expect that everything is same.

Hi DGR,

Have you tried with an inductor with higher current capability? The CDRH4D28NP-270NC seems only has 0.58A current rating.

BR

Patrick

Hi Patrick,
               Yes, I am using an 4.7uH 3A 20% 39mOhm Shielded Wirewound Power Inductor.
jlcpcb.com/.../C48496

Hi DGR,

If the 35ohm resistor is removed, then what is the voltage of VOUT1?

BR

Patrick

10V

Hi DGR,

In your previous reply, Vou1=9.62V but VCOMIN is only 1.72V? Have you confirmed the R6 and R7 are both 511kohm?

Vout 1= 9.62V (connected 35 Ohms Resistance as load)

Vout 2= -3.54V

Vout 3= 460 mV

VCOMIN = 1.72 V

BR

Patrick

Hi Patrick,

                  When the Cap C15 is removed then I am getting around 1.2v at VCOMIN, I also came upon one thing that I found strange, REF is Climbing at 1.6v instead of 1.2v, What might be the problem?

Hi DGR,

Yes, this is strange, have you tried changing the IC with another pcs? Will every IC have the same behavior?

Yes I have tried with Another fresh Board, But it startup and get locked up after few seconds

Have you also disconnected its C2-/MODE pin from GND?

Yes, I did.

OK, could you please capture the start-up waveform of VOUT1, VREF, SW and put them in one oscilloscope screenshot? You can use 3 probes to do this.

Sure, I'll Send the Wave form , But I have Dual Probes at this point of time.

Hi Patrick,

                  I have attached the Startup Waveforms as shown below

Yellow Is VOUT1
Purple is SW

Yellow is SW

Purple is REF

Hi DGR,

Thanks, and could you please capture the waveforms with a longer time, like 1ms/div. I want to see when the IC stops working after power up.

BR

Patrick

Hi Patrick,

                   The Above waveforms are for the board that we are testing in the trailing messages not the Locked up TPS65100 Board.

Hi DGR,

So could you please also capture the waveform of the Locked up board and with longer than 1ms/div? Thanks

BR

Patrick

Hi Patrick,

                  Good News, I have populated a fresh board with fresh components and I can tell that I am getting better results now.

Input voltage 3.3V
Current at Input side =0.043mA

VOUT1=9.946V

VOUT2= -4.78v

VOUT3= 20.2V

VCOM= 4.986v

VCOMIN= 4.85V

REF=  1.21V

These measurements are done without any load.
 I believe we can build fresh batches just to be sure that we have reached our goal.
Next thing - To test these output under load.
And Is there any way of getting 5-6 samples of TPS65100 because the TI portal is showing out of stock?

Hi DGR,

Are you available to ARROW? You can find samples there.

BR

Patrick