TPS62740: Alternative components with wide VIN

Hi Fabio,

TPS62840 is the right low IQ part for the higher VIN operating range. However there is no VLOAD pin feature. Could you let me know what the application is?

Best regards,

Varun

Hi Varun,
Thank you for your reply!

Our goal is for this component to be integrated into battery-powered IoT application designs.
In this case, multiple battery types must be taken into account.
Are there any other similar parts that could be considered?

Best regards,

Fabio

Hi Varun,
Thank you for your reply.

Is there any other similar set of components compatible to the required input range ( even with slightly higher IQ) that could be suggested for this application (i.e. TPS62080DSG or the TPS62200)?  They allow a Vin range up to 6V.  Could this be suitable to 4-cell (4.8V) NiMH batteries ?  

Thank you for your attention.

Best regards,

Fabio

Hi Fabio,

Yes the TPS62080 and TPS62200 are also rated 6V parts.

These are some alternate 6V rated parts -

• TPS6223xx 
• TPS62260
• TPS62290
• TPS62851x

They can be used with the 4-cell NiMH batteries as well.

Is there some concern with the TPS62840 for your application?

Best regards,

Varun

Hi Varun,
Thank you for your reply.

I would like to clarify the following topic.

What would be the best performance / most optimized  part in terms of less High frequency noise (current bursts during the charging period of the inductor) and low frequency ripple when operating in PFM? 
If for instance is the TPS62840 the most recent device and the part that shows the best performance, what are the expected (worst case) levels for these two components considering the entire input voltage range and assuming an output current below 15mA?

Best regards,

Fabio

Hi Fabio,

You could use our WEBENCH tool ( https://webench.ti.com/power-designer/switching-regulator ) to calculate the PFM ripple of the TPS62840 - DLC.

For example for the 2.7 VOUT with default BOM (2.2uH and 10uF effective COUT), you get around  38mV pk-pk ripple with only the parasitic ESR of the output cap included. In reality this can be a bit higher because of the ESL of the output cap. 

For high frequency noise, what frequency range is critical for you? Are you concerned with the PWM bursts with a load step or the EMI associated with the rise/fall time of the SW node during each switching cycle?

Best regards,

Varun

I mean the HF noise component when operating in PFM mode (not PWM).
Please see figure below

Hi Fabio,

The TP62840 doesn't have multiple switching cycles together in PFM as in the figure you shared. There are single switching cycles followed by a pause time. This helps reduce output ripple compared to multiple switching cycles in a burst.

Best regards,

Varun