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LMX2485E: use Vcc=2.0V by own risk

KANJI SHIBATANI
Mastermind 6205 points
Part Number: LMX2485E
Other Parts Discussed in Thread: LMX2485

 

Hello

 

Background

Customer  use LMX2485E for FY18 2Q Mass Production in place of Fujitsu MB15E03SL. Customer had made their ES PCB on last week  and

register setting from MCU( uWire ) works well. ( Thank you for your support)

Their usage is FinRF( 450MHz)– RF N divider(1/384)— output from Ftest/LD =1.17MHz. They do not use charge pump.

 

Question

Customer want to have better sensitivity by selecting Vcc  as lower. ( For their experience, lower Vcc is good sensitivity as shown on Fig2)

That is to say, customer will use LMX2485E at Vcc=2.0V by their own risk, using digital interface spec.;VIH=1.6V(min).

How do you think? Customer want to have your opinion.

Best Regards

LMX2485_replace from MB15F72UL_1212.pptx

  • 0
    TI__Guru** 110530 points
    Hi Shibatani-san,

    have they verified that the sensitively at Vcc=2.0V is much better than at Vcc=2.5V?
    If the difference is not really meaningful, I suggest a min. Vcc of 2.5V, this is the guaranteed operating voltage.
  • 0 in reply to Noel Fung
    Mastermind 6205 points

     

    Dear Noel-san

    Thank you for your reply so quickly. 

    Here is customer's answer.

    As the result of the Customer's PCB using LMX2485E ,RF_Fin sensitivity was following.

    3.3V -18dBm

    3.0V -20dBm

    2.6V -22dBm

    2.0V -26dBm

    Customer think it is obviously  that to lower Vcc improve the sensitivity.

    Also, customer says they had been used Fujitsu MB15E03SL( now EOL) as Vcc= 2.0 by their risk.

    So customer want to have your approval ( or confirm ) about LMX2485E .

    He will release their next design (CS) soon.

     

    Would you please have your opinion?

    Best Regards

  • 0 in reply to KANJI SHIBATANI
    TI__Guru** 110530 points
    Hi Shibatani-san,

    I have consulted my colleague, he thinks it is very risky to operate the device at 2.0V supply. Suggest make min. Vcc=2.5V.