How I control the over voltage using LTC4244 ?

Hi,

 Iam using LTC4244IGN#PBF (ICS CTRLR HOTSWAP PCI BUS 20SSOP) in my design.

        I am using +3.3V,+5V voltages from cPCI backplane. I am using +12V,-12V as supply voltage for LTC4244 which has been take from cPCI back plane.

        In that i have some queries.

        1) How I control the over voltage using LTC4244 ? Is there any over voltage protection in LTC4244 - Hot swap controller?
                    i.e if my input voltage from back plane exceeds more than 3.5V (in 3.3V supply) or
                    if my input voltage exceeds more than 5.5V (in 5V supply) will LTC4244 allow ??

        2) Is precharge voltage is available for only at the time of cPCI board insertion and extraction?
                                                or
       Is prechagre voltage will available when board is powered on and Is it won't turned off until the cPCI module removed    from cPCI slot??

        3) Is 1V is sufficient for pull up voltage for PCI bus(Note : I have used 3.3V IO bus) ?? shall I have to provide additional pull resistor for OFF/ON#,PWRGD#,FAULT# with LONG(VIO) voltage?

        4) What if, zero resistor is used at Rsence resistor ?
                                               or
           What if i have n't use any Rsence resistor ?


Regards,

Tendulkar S

Parents
  • 0
    •  Analog Employees 
    on Sep 17, 2017 3:32 AM

    Tendulkar,

    1) How I control the over voltage using LTC4244 ? Is there any over voltage protection in LTC4244 - Hot swap controller?
                        i.e if my input voltage from back plane exceeds more than 3.5V (in 3.3V supply) or
                        if my input voltage exceeds more than 5.5V (in 5V supply) will LTC4244 allow ??

     The LTC4244 does not have an OV pin to shutoff when the input is higher than 3.3 or 5.5V. Protection against OV transients should be done using TVS diodes. As long as the voltage does not exceed the abs max rating of 13.5V you should be fine.

     

     

            2) Is precharge voltage is available for only at the time of cPCI board insertion and extraction?
                                                    or
           Is prechagre voltage will available when board is powered on and Is it won't turned off until the cPCI module removed    from cPCI slot??

     

     

    Precharge voltage is available as long as the device is on and atleast one long 5V pin is connected.

     

            3) Is 1V is sufficient for pull up voltage for PCI bus(Note : I have used 3.3V IO bus) ?? shall I have to provide additional pull resistor for OFF/ON#,PWRGD#,FAULT# with LONG(VIO) voltage?

     

    The threshold of a logic high on the PWRDG# pins is 2V so you will need the 3.3V pullups.

     

            4) What if, zero resistor is used at Rsence resistor ?
                                                   or
               What if i have n't use any Rsence resistor ?

     

    If no RSENSE is used then there will be no OC protection. If no upper current limiting bound is desired you will short the RSENSE resistor connection. However this is not recommended.

Reply
  • 0
    •  Analog Employees 
    on Sep 17, 2017 3:32 AM

    Tendulkar,

    1) How I control the over voltage using LTC4244 ? Is there any over voltage protection in LTC4244 - Hot swap controller?
                        i.e if my input voltage from back plane exceeds more than 3.5V (in 3.3V supply) or
                        if my input voltage exceeds more than 5.5V (in 5V supply) will LTC4244 allow ??

     The LTC4244 does not have an OV pin to shutoff when the input is higher than 3.3 or 5.5V. Protection against OV transients should be done using TVS diodes. As long as the voltage does not exceed the abs max rating of 13.5V you should be fine.

     

     

            2) Is precharge voltage is available for only at the time of cPCI board insertion and extraction?
                                                    or
           Is prechagre voltage will available when board is powered on and Is it won't turned off until the cPCI module removed    from cPCI slot??

     

     

    Precharge voltage is available as long as the device is on and atleast one long 5V pin is connected.

     

            3) Is 1V is sufficient for pull up voltage for PCI bus(Note : I have used 3.3V IO bus) ?? shall I have to provide additional pull resistor for OFF/ON#,PWRGD#,FAULT# with LONG(VIO) voltage?

     

    The threshold of a logic high on the PWRDG# pins is 2V so you will need the 3.3V pullups.

     

            4) What if, zero resistor is used at Rsence resistor ?
                                                   or
               What if i have n't use any Rsence resistor ?

     

    If no RSENSE is used then there will be no OC protection. If no upper current limiting bound is desired you will short the RSENSE resistor connection. However this is not recommended.

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