TPS2663: The dVdT slew rate cannot be adjusted.

Hi Dong,

Please check the solderability of CdVdT capacitor. The present tdVdT of 500usec resembles an OPEN CdVdT case.

Best regards,

Rakesh

Yes, I checked the soldering and there was no problem.
It is the same even if CDVDT (0.1uF) is replaced.
Thank you

Ok Masaaki.

Can you try on different boards, different units with different Cdvdt values. If issue remains same, we need to submit the few units for failure analysis

Best Regards, Rakesh

Hello rakesh

I have a TPS16630-32EVM.
The tdvdt of the TPS16630-32EVM will be the value as set by the capacitor.
It seems that TPS26633PWPT cannot be used just by connecting a capacitor to the dvdt terminal.

Thank you

Hi Masaaki,

Can you please confirm on the outcome of the result with different units and with different Cdvdt values to debug the issue.

Best Regards, Rakesh

Hello rakesh

I will attach an image.

Cdvdt_0r1uF.jpg : Cdvdt=0.1uF

Cdvdt_1uF.jpg : Cdvdt=1uF

Cdvdt_10uF.jpg : Cdvdt=10uF

COUT=660uF, ILIMIT=1.9A 

CH1=Vin CH4=Vout CHM=Iin CHM 1A/digit

Thank you

Hi Masaaki,

The input current and output slew rate remains same irrespective of changing Cdvdt and Cout, which is not expected. 

How did you measured input current ?

Can you check whether slew-rate of dVdT pin voltage is changing with different Cdvdt by probing directly on the dVdT pin.

Best Regards, Rakesh

Hello rakesh
The input current is the voltage across the input power supply series resistance 0.47Ω.
attached image
CH1: Vin CH3: dvdt signal CH4: Vout CHM: Iin
CH3 = 500mV / digit　CHM=1A/digit

Thank you

Hi Masaaki,

The dvdt pin voltage should reach 4.17V. Something wrong here. 

Are you seeing same behavior on other units as well ?

Can you share top marking of these devices

Best Regards, Rakesh

Hello Rakesh

It is the same even if ic is exchanged.

I will attach a photo of ic.

The photo is of the same taping that has not been used yet.
The chip mounted on the board is written as "TPS26633.09KG4.C4R".

Thank you.

Hi Masaaki,

Thanks I will check.

One quick question: Have you probed dvdt voltage on the IC side that is on the pin-10 right at the device - right ?

Can you also share board layout files.

Best Regards, Rakesh

Hello Rakesh
I directly observed pin 10 of the IC, but it is the same.
Make another board with a simple circuit.
The circuit diagram is attached.
Thank you

Hi Masaaki,

Can you leave SHDN/ pin open and test ?

Best Regards, Rakesh

Hello Rahesh
I had a good result when I opened the SHDN signal.
The slope of dvdt is also 60msec as desired.
I was wrong in processing the SHDN signal.
Attach a successful image.
Thank you for your polite support
Thank you