LM70880-Q1: LM70880-Q1

HI Divyapriya,

We have plenty of parts that can suit your needs for an IBB configuration. I think the LM70880-Q1 is not needed for your application. As an example, you can try the LMR43620-Q1 which is a 36V/2A device.

We have a PSPICE model available for the LMR43620-Q1. The model can be found:

https://www.ti.com/product/LMR43620-Q1#design-tools-simulation

Also, below is a link that explains more on IBB (inverted buck-boost) topology.

https://www.ti.com/lit/an/snva856b/snva856b.pdf

Please go to Ti.com website to find our latest buck regulator offerings.

Ben

Hi Ben,

Thankyou for your previous response.

How can we use Webench power designer for drafting the IBB configuration using  LMR43620-Q1.

Could you also provide calculator tools or spreadsheets for determining component values and analyzing the Bode plot for stability analysis?

Thank you for your support. We look forward to your guidance.

Regards,

Divyapriya.

Hi Divyapriya,

Most of our tools (Webench/PSpice/quick start calculators) do not support IBB configuration although at Texas Instruments we have literature to help you with your design. One document is already listed above in the previous post. Below are a few design examples to help you with your design.

https://www.ti.com/lit/an/snva897/snva897.pdf

https://www.ti.com/lit/an/snvaa65/snvaa65.pdf

https://www.ti.com/lit/an/slvafp0/slvafp0.pdf

Ben

Hi Ben,

Thankyou for your previous response.

We are using  LMR43620-Q1  in an Inverting buck boost configuration to generate -12V output from a 12V input with 2A output current. I have attached a snapshot of the schematic we designed for this purpose. Could you please review the design and confirm whether it will work effectively in our application?

Thank you very much for your assistance. We look forward to your guidance.

Best Regards,

Divyapriya.

Hi Divyapriya,

The schematic looks good except for PGOOD where the PGOOD pin would need to be level shifted to output the correct logic level. See example below:

Ben

Hi Divyapriya,

Are there any updates?

Ben

Hi Ben,

Thankyou for your previous response.

We have the PSPICE model of  LMR43620-Q1, can we use this model in LTSPICE for verifying IBB configuration.

How can we use this model in PSPICE for verifying IBB configuration.

Regards,

Divyapriya.

Hi Ben,

Also, for selecting inductor which calculation method we have to follow.

When calculating the inductor value using the first method, as outlined in the datasheet, the results differed from those obtained using the second calculation method as outlined in IBB configuration reference.

1) 

2)

Regards,

Divyapriya.

Hi Divypriya,

The first equation is for a buck converter configuration. The second equation is for a buck-boost converter configuration. 

Therefore, an IBB circuit configuration will use the second equation.

Ben

Hi Ben,

Could you please look into this query.

Regards,

Divyapriya.

Hi Divyapriya,

What is the query?

Ben

Hi Ben,

We have the PSPICE model of  LMR43620-Q1, can we use this model in LTSPICE for verifying IBB configuration.

How can we use this model in PSPICE for verifying IBB configuration.

Regards,

Divyapriya

Hi Divyapriya,

Unfortunately, our PSPICE models do not work on LTspice and do not work in an IBB configuration.

Have you tried ordering the EVM and verifying the IBB design?

Ben

Hi Ben,

We are not going to order EVM for  LMR43620-Q1. We are implementing the IBB configuration directly in our circuit design.

Could you please suggest other way to verify IBB configuration of LMR43620-Q1.

Regards,

Divyapriya.

Hi Ben,

Thankyou for your previous responses.

Could you please suggest an IC that can directly provide a negative output voltage of -12V(with 2A current ) from an input voltage of +12V, without using a buck regulator in inverting mode?

Regards,

Divyapriya.

Hi Divyapriya,

You might want to try the buck-boost group and post a new thread in their forum for advice on an IC that will fit your needs/application. 

If there are no further questions, please close this thread by clicking on resolved. Thanks,

Ben

Hi Ben,

Thankyou for your insightful suggestions. It was very helpful.

Regards,

Divyapriya.