AWR6843: Question about PMIC_CLKOUT frequency setting

Hayden Kim

Genius 15580 points

Part Number: AWR6843

Hello Champs,

With below register settings, PMIC_CLKOUT of 12MHz frequency is working.

* EXTCLKSRCSEL - 0x2 (600MHz PLL)

* EXTCLK2DIV : 0x0 (div1)

* Average of MIN Div and MAX Div : 0x32 (50)

[Q1] (AWR6843) Is it possible to have PMIC_CLKOUT of 24MHz frequency? If it is possible, can you guide how to set the registers?

[Q2] (LP87524) When using the PMIC_CLKOUT as 12MHz, how to set the PMIC (LP87524) switching frequency as 12MHz?

When he changed the PMIC register (EXT_CLK_FREQ) as 0x11 (12MHz), the switching frequency was still 4MHz, not 12MHz. (The PLL_CTRL setting was 0x8B [1000 1011])

Is there something more to do for the switching frequency of PMIC?

Thanks and regards,

Hayden

over 2 years ago

+1 CHETHAN KUMAR Y.B. over 2 years ago

TI__Mastermind 25795 points

Hello Hayden,

Could you please help us to understand why do you want switch LP87424 to higher frequency? What is the motive for this experiment?

Please note that LP87524 cannot switch more than 4MHz. See below datasheet

Thanks and regards,

CHETHAN KUMAR Y.B.

0 Hayden Kim over 2 years ago in reply to CHETHAN KUMAR Y.B.

TI__Genius 15580 points

Hello Chethan,

Thanks for your answer. The purpose is to increase power efficiency.

Best regards,

Hayden Kim

0 CHETHAN KUMAR Y.B. over 2 years ago in reply to Hayden Kim

TI__Mastermind 25795 points

Kim,

There is inherent max limit on the frequency of the switch mode converter most of these converter cannot switch higher than 4MHz. Hence your observations are valid and would show 4MHz switching frequency. At higher frequency switching loss dominates as compared to conduction losses and degrades the efficiency.

Thanks and regards,

CHETHAN KUMAR Y.B.

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AWR6843: Question about PMIC_CLKOUT frequency setting