UCD90120A: abnormal enable signal

Hi, Hailiang,

Can you send the project file (.xml) generated using Fusion GUI when GPIO11/PIN23 has abnormal signal? What do you expect the signal level and what is abnormal?

Hi Anne，

Pls refer to below file. 

UCD90120A+2.3.4.0+Address+52+Project+File.xml

Pls see the wareform. I expect the pulse on the IO port waveform (red) to disappear. Currently only GPIO11/PIN23 has abnormal waveforms, and the impedance of this pin to ground is not abnormal. Could you pls help?

Regards,
HL

Hi, Hailiang,

Can you tell us what waveform referenced to what pins? 

Is the red waveform referred to Enable pin on rail #1, GPIO11, pin #23?

Regards

Anne Ngo

Texas Instruments

HI

Please provide your schematics. What's the slew rate of the VCC?

Regards

Yihe

Hi Anne,

All the signal is refer to VSS. 

The red waveform is the signal of GPIO11, which is the enable signal of the subsequent power supply. Green is the output of the power supply. The waveform of UCD Vcc is blue.

Yihe,

Pls refer to the schematic. 

Do you mean the slew rate of 3.3VCC (The waveform in Green)? 

R1141-M0020-02_R01_Switchboard_SC_20190604.pdf

Regards,
HL

Hi

You can try to increase the slew rate of VCC(Blue) to see whether the problem go away .

The glitch is about 1.2V. is this problem for the downstraem converter?

Regards

Yihe

Hi Yihe，

Increasing the Vcc slope seems to help. When the rise time of VCC is greater than 1.5ms, no abnormal waveform will appear. Why is it related to the slope of Vcc? Is there a schematic circuit reference?

Regards，
Hailiang

Hi Yihe，

The customer has a project that is about to be mass-produced, and the rise time of Vcc is 3.5s. Since the hardware cannot be modified, I would like to know if there is a solution through software.

Regards，
Hailiang