TPS61022: Pour copper GND Layout

Riccardo Straga

Prodigy 45 points

Part Number: TPS61022

Tool/software:

Hello,

I'm designing a 3.6V 2A boost. I Have few question about the layout.

1) Is it the layout correct ? GND are connected via the GND area under the regulator (Layer 2 and Layer 4) :

2) I have doubts when I create a GND pour copper zone on Layer 1.

Do I have to keep the "GND areas near to the device" separated to the GND pour area (connected only via Layer 2 and Layer 4 that are not shown on this picture):

Or is it OK if the pour copper is connected to the "GND areas" near to the device (and also via Layer 2 and Layer 4 that are not shown on this picture):

Best regards,
Riccardo

6 months ago

0 Nathan Ding 6 months ago

TI__Genius 10135 points

Hi Riccardo,

The layout is ok, both two GND pour copper are ok for TPS61022. If possible separated GND pour area is a little better, but the other way is also low risk.

Please refer to this app note for the layout guildelines of TPS61022.

https://www.ti.com/lit/an/slvaes4/slvaes4.pdf?ts=1697076086366&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPS61022

And more, can I check your schematic? What is your output capacitor?

I find that you only place one capacitor on the VOUT, that may not proper for TPS61022, please double check the effective capacitance to make sure that it is within the range of ROC table.

Regards,

Nathan

0 Riccardo Straga 6 months ago in reply to Nathan Ding

Prodigy 45 points

Hello,

thank you for the the app note.

Here the schematic :

My load is a LTE-M module, do you suggest to increase the output capacitor ? Is there any downside to increase that capacitor ?

Best regards,

Riccardo

+1 Nathan Ding 6 months ago in reply to Riccardo Straga

TI__Genius 10135 points

Hi Riccardo,

The effective capacitance of 100uF/0805 is about 20~30uF, depends on the specific capacitor you use. The effective capacitance is ok for TPS61022.

But we don't recommend to use only 1pcs 100uF capacitors on the output, because the resonant frequency of 100uF cap is generally smaller than the switching frequency of TPS61022 (1MHz), which will introduce larger ESL.

So we recommend to place at least 1pcs 22uF capacitors (higher resonant frequency) on the output.

Considering that the application is LTE module, I guess you may require the output voltage of TPS61022 can't drop too low. Therefore we recommend to leave a feedforward capacitor and resistor placeholder for potential load transient performance improvement, as below (C10, R4).

You can refer to these app notes and calculation tool for the design of C10.

R4 usually recommended to set about ~ 50 ohm.

https://www.ti.com/lit/an/slva834/slva834.pdf

https://www.ti.com/lit/an/slvaer4/slvaer4.pdf?ts=1720146774945&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPS61022%253FkeyMatch%253DTPS61022%2526tisearch%253Dsearch-everything%2526usecase%253DGPN-ALT

https://www.ti.com/tool/download/SLVC760

Regards,

Nathan

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TPS61022: Pour copper GND Layout