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LM3481Q and LM3488-Q1 datasheet

belenie amoranto
Prodigy 160 points
Other Parts Discussed in Thread: LM3488, LM3481, LM3478

Hello,

I have the following question regarding the LM3481Q and LM3488-Q1.

 

-          In the datasheet of the first the shutdown current is listed as 10µA in the key specifications, and 5µA in the description text (2nd paragraph), the FA/SYNC/SD pin description, and in the Frequency Adjust / Synchronization / Shutdown section.  For the LM3488-Q1 it is listed as 5µA in the description and key specifications, and 10µA in the FA/SYNC/SD pin description and the Frequency Adjust / Synchronization / Shutdown section.  Which number is correct and are the parts practically equivalent as far as the shutdown current is concerned?

-          To increase the slope compensation the circuit shown for the LM3481Q (figure 22) and the one for the LM3488-Q1 (figure 25) have the positions of RSL and CSEN reversed.  Is this correct and they are different?

 

Thanks for the help.

 Belenie

  • 0
    TI__Intellectual 1775 points

    Hi Belenie,

    - Both ICs have a typical shutdown quiescent current of 5µA for Vin=5V. This is shown in the EC table of both the LM3481 and the LM3488.

    However, the LM3481 datasheet shows a max shutdown current of 10µA over temperature while the datasheet for the LM3488 shows a 7µA max. The shutdown current will increase with the input voltage. The datasheet for the LM3481 specifies a shutdown current at Vin=12V of 9uA typical with a max over temperature of 15uA. It is likely that the shutdown current for the LM3488 will be similar to that of the LM3481 at Vin=12V.

    - The proper schematic is that of the LM3481. The capacitor is placed after the additionnal resistor next to the ISEN pin. See the evaluation module for the LM3481 and the LM3478.

    I hope this helps.

    Florent Boico