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LTM4622 &LTM4705 Frequency Set for Dual Output voltage

Category: Hardware
Product Number: LTM4622 LTM4705

Hi 

We are using LTM4622 Dual Output Voltage part for Vout1 3.3V and Vout2 - 1.8V.

The datasheet specifies Frequency pin  : For 1.8V, FREQ Pin should be left open to set 1MHz and For 3.3V FREQ Pin to be connected ground with 324K to set 2MHz

Q1: In Two different output (LTM4622) Switching frequency Fsw of regulator will be same for both output, Right?

Q2: In my case, Where I've Vout1-3.3V and Vout2- 1.8V, What should be the Switching frequency set to?

If I set Fsw- 1 MHz, For 3.3V, Inductor ripple current as per the datasheet calculation, it results 2.392 A which is exceeding "1.2A peak-to-peak inductor ripple current" 

Same for LTM4705, Vout1-3.3V and Vout2- 1.35,

What should be Fsw?

Top Replies

  • FormerMember
    FormerMember
Mar 6, 2023 in reply to KLN +1 verified

You should use the higher switching frequency if you wish to use the parts you mentioned.

Regards,

Jhun