TPS536C7: No output on a prototype board using TPS536C7

Hi,

If the output shows 0V, please double check that it has not been shorted to GND.

The VOUT UV Fault and PH_ERR reported in GUI suggest an issue at the power stage(s) when regulation is first enabled.

Can you capture waveforms of PWM, VSW, TSEN and CSP at the power stage the moment this fault occurs? You may need to trigger on TSEN, CSP or the first PWM rising edge to catch the fault. This should provide more information on what exactly is going wrong.

Regards,

Troy

Hi, Troy.

Thanks to reply.

First, I checked the Vout and GND shorts,
And It was not shorted.

Second, I captured the waveform of PWM, TSEN and CSP.
there was no VSW, so I didn't take it.

Also, because we didn't know when the fault occurred,
Instead, it triggers CSP after power and Vin are turned on.

I attached the waveform.
Ch1: CSP, Ch2: PWM, Ch3: TSEN.

The second image is an enlarged waveform of the part where the PWN signal is thought to be out.

The PWM signal is output about 220us, and then fixed at about 1.5V.
Can you please confirm?

Best regards.

Hi Troy

Thanks to reply.

I understand it.

By the way, how does the TPS536C7 detect the presence or absence of response from the power stage.

Best regards.

Hi, Troy

Thanks to reply.
Excuse me, but let me ask you an additional question.

The following points were observed in the PWM waveform.　

It is set to 2 phases (PWM1 and 2 are used pins), and other PWMs (PWM3~12) are disabled.

・In spite of  there is no output, the period of high level is short.

・There is a period when PWM1 and 2 overlap

・There is a period of alternating output with PWM1 2 pulses and PWM2 3 pulses.

I think it's strange .

A 35Ω resistor is connected to the output.　The current capability of the Power Stage is not a problem.

Is this behavior caused by the controller settings?

If so, could you tell me how to improve it?

Ch1：PWM1, Ch2：PWM2

Best regards.

Hi,

I am not sure what's causing that behavior, but there's a couple settings you can check that may help.

• If you have phase shedding enabled, check the minimum number of phases isn't 1.
• Check tblank is not very high, if it is can try lowering it below 60

Regards,

Troy

Hi, Troy.

Thanks to reply.

・I have pahse shedding disable.
・I set tblank to 30ns.

I attached the config file.
I'm sorry but Could you check it?

TPS536C7 5.0 Address 88 Project File.xml

Hi, Troy.

Thank you for confirming.
Do you have any idea what the cause is in terms of hardware?

Best regards.

Hi,

Are you able to share your schematic, so I can look for any issues?

Regards,

Troy