PF3000 SWBST minimum load

[philipp_blumberg]

Do I understand the PF3000 datasheet right, that the SWBST 5V regulator needs 600mA of minimum load (Continuous load current I_SWBST, Table 13)? How is the light load behaviour? Don't see it properly specified in the datasheet.
All values for Table 13 are specified with I_SWBST=100mA, so this is in conflict with the 600mA min. current.
Also, is the Peak Current limit I_SWBSTLIM the max. continuous current or peak pulse current?

Could you please clarify?

- Minimum continuous load current for SWBST
- Light load behaviour
- Max continuous load current for SWBST

Thanks!

[philipp_blumberg]

Good morning,

thanks for the clarification!

Is there NXP internal data on temperature derating of these 600mA? As these values are specified over the full temperature range, is there data for 25°C only?

Kind regards,

Philipp

[JozefKozon]

Good morning Philipp,

unfortunately no. We don't have such data. Only the general data in the datasheet are available.

With Best Regards,

Jozef

[philipp_blumberg]

Good morning,

is there a possibility to get more insight on the capabilities of the SWBST output? 

With the PF3000 we would build a system that expects five-digit sales figures, our customers are already ordering (no sales nonsense included). But, from time to time we would need slightly more than 600mA. When you say, the peak current limit can be drawn for only a few seconds, it would be highly interesting what these "few seconds" are. When it's related to the switching losses then one could calculate approximate power limits for puls widths and ambient temperatures. This would be very interesting to estimate the capabilities of SWBST output. Who can we contact to get more insight on this? Or shall we contact our distributor?

[JozefKozon]

Good morning Philipp,

I have send the request for the SWBST output capabilities description to an application team. As soon as I will receive an answer I will definitely reply to you. 

With Best Regards,

Jozef

[JozefKozon]

Good morning Philipp,

please see below a reply from the application team. I am afraid the SWBST of the PF3000 is not capable to provide 790mA or more, than 600mA.

DESCRIPTION

I am sorry for the late reply and thank you for your detailed description.

We have to let customer to follow the specification, if the load is over the 600mA which is confirmed in Datasheet, we can't give customer one promise for the work performance, as the devices is sampled in product line to follow the specification, so it is hard to give customer any suggestion and commitment which is not limited in datasheet.

With Best Regards,

Jozef

[philipp_blumberg]

Good morning Jozef,

thanks for your reply!

It is also not possible to get a 85°C derating for the 600mA value?

Greetings, Philipp

[JozefKozon]

Good morning Philipp,

I will send your question to the application team. Meanwhile, I have checked our product portfolio for available PMICs and I have found one with a boost current capability from 800mA to 1A  for 5V, and up to 1.1A for 5.74V. Depending on VPRE settings. Please refer to section 11. in a VR5510 datasheet attached. I will also ask the application team if they would recommend this PMIC for your application. 

With Best Regards,

Jozef

[JozefKozon]

Good morning Philipp,

actually could you please provide more details of your application? What do you need to supply? The VR5510 has 3 Buck regulators, 3 LDO regulators and one Boost regulator. 

With Best Regards,

Jozef

[philipp_blumberg]

Thanks for your reply!

What is I_SWBSTLIM then in this context? This value DOES sound like a maximum continuous load current value

[philipp_blumberg]

Thank you for your reply!

What is I_SWBSTLIM then in this context? This value from the datasheet DOES sound like max continuous load  corrent for SWBST

[JozefKozon]

Dear Philipp,

the value I_SWBSTLIM is only a peak value for a very short time (us). The continuous current for the boost output is 600mA.

Please refer to the Table 35. in the datasheet. The maximum load current for SWBST is stated there 600mA.

With Best Regards,

Jozef

[JozefKozon]

Dear Philipp,

the ISWBST values in the Table 13. are the guaranteed values. Meaning, that for the supply voltage at VIN pin from 2.8V to 3.0V it is guaranteed, that the PMIC is capable to provide minimally 500mA at the SWBST output and for the supply voltage at VIN pin from 3.0V to 4.5V, 600mA is guaranteed.

- Minimum continuous load current for SWBST

[A] 0A

- Light load behavior

[A] There is no issue in light load, however if any of the Bucks, Boosts or LDOs are not used, there is a recommendation how to connect the unused pins.

- Max continuous load current for SWBST

[A] Maximal continuous load current for SWBST are not stated. Only the minimal continuous currents are guaranteed. For 2.8 V ≤ VIN ≤ 3.0 V it is 500mA and for 3.0 V ≤ VIN ≤ 4.5 V it is 600mA.

With Best Regards,

Jozef

[JozefKozon]

Dear Philipp,

- Max continuous load current for SWBST

Just to avoid misunderstanding. The maximum continuous load current for SWBST is not stated, but it is probably only slightly higher, than the minimum continuous load current. 

For 2.8 V ≤ VIN ≤ 3.0 V it is 500mA and for 3.0 V ≤ VIN ≤ 4.5 V it is 600mA.

With Best Regards,

Jozef