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LM74703-Q1: LM74703QDDFRQ1

Shachar Armon
Prodigy 230 points
Part Number: LM74703-Q1
Other Parts Discussed in Thread: LM74800-Q1

Tool/software:

Hi,

We are using currently LTC4359IDCB, 

in the new design I like to change it to LM74703-Q1

the application is classic OR ideal diodes (using two OR controllers) with reverse protection for battery 

the first is for external DC source powering the system- drives single NFET

the second is for internal battery source- drives 2 NFET's back to back  (drain sides to the battery and to the system)

and the external battery charger connect also between the battery to the back to back NFET's 

the mains system scenarios:

1. system sourcing from the external 

2. system sourcing from internal battery 

3. fully hot swap capability between the sourcing, meaning the system remains operation without any interruptions all conditions of connect/ disconnect the sources 

As mention I intend to use LM74703QDDFRQ1

can you emphasis the different between LM74703-Q1 to LM74700Q in general and what is the best case for my requirements?

BR

Shachar 

  • 0
    TI__Mastermind 46660 points

    Hi Shachar,

    LM74700 and LM74703 are the same devices functionally. LM74703 offers an additional pin called FETGOOD.

    I see that you have a requirement of driving back to back FETs,  it can not be done by LM74700 or LM74703.

    Please consider LM74800-Q1.

    A configuration as shown will fit your use case.

    LM7480-Q1 Ideal Diode Controller with Load Dump Protection datasheet (Rev. C)

    Regards,

    Shiven Dhir

  • 0 in reply to Shiven Dhir
    Prodigy 230 points

    Hi Shiven,

    Thank you for the detailed response, I asked for the LM74700 for the following responses:

    It simpler ICs, lower cost and with other brand compatible footprint - this is always good for the mass production supply chain.

    our application required to immediate switch to battery source while the external power source removed and vise versa

    I believe the typical application and the advantages of the LM74800-Q1 isn't best fit for our need  

    we need quick detection of window comparator (not just OV or UV), meaning the internal comparator can't help us here

     

    I would like to use the same circuit with minimal adaptation, just replace to LM74700, what do you think?

    BR

     

  • 0 in reply to Shachar Armon
    TI__Mastermind 46660 points

    Hi Shachar,

    LM74700 cannot drive back to back FETs.

    Regards,

    Shiven Dhir