topic Re: PF3000 current limit protection in i.MX Processors

PF3000 current limit protection

frankyhsu — Wed, 18 Apr 2018 07:25:00 GMT

I am checking the PF3000 current protection and found that the PMIC power input is continuous to sink large current when I short the output cap of the power rail.

For LDOs, I study the datasheet and found the PMIC will not be protected when power up. If we have the short circuit (bad board) on the LDOs, we might cause high heat when we supply the power input to PMIC? The LDO will not be turned off?

For switching power, there is even no any description about the regulator turned off protection but showing the "current limit event" only. Does it mean the over current on switching power will have the same problem that we have no way to turn off it unless we shut down the PMIC by letting the PWRON pin to low once we get the event?

For all LDO and switching power rails, when we have short circuit on caps or ICs, the PMIC will not have any protection mechanism to prevent the over current issue?

Re: PF3000 current limit protection

igorpadykov — Wed, 18 Apr 2018 10:02:10 GMT

Hi Franky

there are current limits, for example SW1AILIM in SW1ACONF register

Table 142. SW1ACONF PF3000 Datasheet, IVINUVILIMIT in

Table 6. Electrical characteristics – front-end input LDO, ISWBSTLIM

in Table 13. Static electrical characteristics - SWBST,

ILDO1LIM in Table 17. Static electrical characteristics - VLDO1

https://www.nxp.com/docs/en/data-sheet/PF3000.pdf

During board bring-up one can follow i.MX6Q Hardware Development Guide

Best regards
igor
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Re: PF3000 current limit protection

frankyhsu — Thu, 19 Apr 2018 03:46:04 GMT

1. The current limit in PF3000 is used for fault event and need to turn off externally by using PWRON pin?

2. It means an external current limit is required for PF3000 when boot up.

Re: PF3000 current limit protection

igorpadykov — Thu, 19 Apr 2018 04:47:33 GMT

you can follow i.MX7D Sabre reference design which is working fine with pf3000

Schematics (2)
Design files for i.MX 7Dual
Design files, including hardware schematics, Gerbers, and OrCAD files for i.MX 7Dual (REV D)
http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/i.mx-applications-processors/i.mx-7-processors/i.mx-7dual-processors-heterogeneous-processing-with-dual-arm-cortex-a7-cores-and-cortex-m4-core:i.MX7D?fpsp=1&tab=Design_Tools_Tab

I beileve external current limiter also can be used if necessary.

Best regards
igor