TPS6521905: Are there any registers I should check to change the output voltage on EVM?

Kyohei

Expert 1380 points

Part Number: TPS6521905

Tool/software:

I am evaluating the TPS6521905 EVM.

The output voltage waveforms of BUCK3 and LDO1 on the oscilloscope no longer change when I adjust them via the GUI.

Are there any registers I should check to change the output voltage?

(Initially, the oscilloscope waveforms for BUCK3 and LDO1 were dynamically changing, but they stopped changing at some point.

BUCK1 and BUCK2 are still dynamically changing in response to GUI adjustments.)

Best regards,

Kyohei

9 months ago

0 Kyohei 9 months ago

Expert 1380 points

Even though the GUI is set to 0.75V, the oscilloscope shows a voltage of around 1.2V with no change.

0 Matt Sunna 9 months ago in reply to Kyohei

TI__Guru* 81034 points

Hi Kyohei,

It is best to disable the outputs when changing voltages. There are many registers that will not take effect while the outputs are active to prevent issues in the system.

Best regards,

Matt

0 Kyohei 9 months ago in reply to Matt Sunna

Expert 1380 points

Hi Matt,

I tried disable the outputs when changing voltages.

But BUCK3 remains stuck at 1.3V, and LDO1 only outputs 1.9V.

Is there anything else I should check?

Best regards,

Kyohei

0 Sam 9 months ago in reply to Kyohei

TI__Expert 4175 points

Our engineer for this thread is currently out of the office for the US Thanksgiving holiday. Responses will be delayed to week of December 1. Thank you for your patience.

0 Kyohei 9 months ago in reply to Sam

Expert 1380 points

Thank you for your reply, Sam.

I am waiting for everyone’s holiday to end.

I have an additional question:

I set the LDO1_VOUT register to 00000111 on the GUI and wrote the program.

However, the output voltage observed on the oscilloscope is stuck close to 2V.

What could be the cause of this?

Best regards,

Kyohei

0 Matt Sunna 8 months ago in reply to Kyohei

TI__Guru* 81034 points

Hi Kyohei,

You may want to check the configuration of the digital pins that can be used to control some of the output voltages. Read the datasheet carefully to understand how these pins are configured and whether to drive the input high or low. For example:

And this:

Best regards,

Matt

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TPS6521905: Are there any registers I should check to change the output voltage on EVM?