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LM61460-Q1: Inquiries about substitutes

MJ Jeon
Genius 5240 points
Part Number: LM61460-Q1
Other Parts Discussed in Thread: LM61440, LMQ61460

Hi, TI Support Team

The customer is looking for a replacement product due to a delivery issue.

In order to use LM61460AASQRJRRQ1, we are checking replacement products due to a delivery issue during development.

1. Please check pin-to-pin alternatives. (Parts available for delivery)

I am reviewing LMQ62440APPQRJRRQ1.

2. Switching Freq of LM61460AASQRJRRQ1. The setting was performed at 400kHz by applying Rt, but when LMQ62440APPQRJRRQ1 is applied, Rt is applied to the MODE/SYNC pin and the Switching Freq.

Is it possible to change

It seems possible in the Electrical Spec. below, but please confirm.

Please check quickly.

Thanks.

Regards,

MJ

  • +1
    TI__Mastermind 27045 points

    Hi MJ,

    LM62440 has fixed 2.1MHz freq, the Fsw only can be changed by applying clock on SYNC/MODE pin.

    If load current below 4A, you check LM61440 availability.

    B R

    Andy

  • 0 in reply to Andy Chen
    Genius 5240 points

    Hi, Andy

    Thank you for your answer.

    "If load current below 4A, you check LM61440 availability."

    What does the above comment mean?

    Does it mean that it is better not to apply to products under 4A?

    In the datasheet, there is an explanation about the part where Rt=6kohm is applied as shown in the figure below.

    Is this part unrelated to Switching Freq.?

    Is Switching Freq. a part that can only be changed with an external clock?

    Customers are concerned because higher frequencies can affect performance such as EMI.

    Thanks.

    Regards,

    MJ

  • 0 in reply to MJ Jeon
    Genius 5240 points

    Hi, Andy

    "If load current below 4A, you check LM61440 availability."

    I understand what you replied.

    However, the above product cannot be used due to delivery issues.

    The above additional inquiries are related to the LMQ62440A.

    Please check and reply.

    Thanks.

    Regards,

    MJ

  • 0 in reply to MJ Jeon
    TI__Mastermind 27045 points

    Hi MJ,

    The Data sheet explain it very clearly that LMQ62440AP has no RT pin to adjust freq, the switching only can be adjusted by applying ext clock on SYNC pin. that's why I recommend LM61440 if customer can't change the circuit.

    it definitely require EMI and thermal evaluation if change Fsw from 400KHz to 2MHz, but it may not require PCB layout change if original circuit and layout was well designed.

    b R

    Andy 

  • 0 in reply to Andy Chen
    Genius 5240 points

    Hi, Andy

    Thank you for your answer.

    I have a more question.

    If there is an alternative with the spec of output current=6A, please recommend it.

    It's good to be pin to pin.

    Please recommend a product that requires a little change for the PCB.

    Thanks.

    Regards,

    MJ

  • 0 in reply to MJ Jeon
    TI__Guru 50120 points

    Hi MJ,

    Is there a reason why you can't use the LMQ61460AASQRJRRQ1 device which is a 6A pin-to-pin compatible with the existing LM61460AASQRJRRQ1 that customer has? (Digikey link).

    This device should be the closest to customer schematic and not require any PCB layout change. 

    Regards,

    Jimmy

  • 0 in reply to Jimmy Hua
    Genius 5240 points

    Hi, Jimmy

    Thanks for the reply.

    I have additional questions.

    What is the difference between the above two products?

    Thanks.

    Regards,

    MJ

  • 0 in reply to MJ Jeon
    TI__Mastermind 27045 points

    Hi MJ,

    LMQ61460 integrates two bypassing caps between VIN and PGND in the IC package to improve EMI performance. other electrical spec is the same.

    B R

    Andy