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LM2936Q-Q1: Datasheet clarification

Marvn Arcangel
Genius 12475 points
Part Number: LM2936Q-Q1

Hi Team,

I needed your help in clarifying conflicting information that I found in the datasheet for this device.

(1) In section 6.3, and  7.3.1, the recommended operating condition for LM2936Q is 40V and 60V max for LM2936QH,

But section 9 also states that LM2936Q at 60V. Can LM2936Q work at 60V? for how long?

(2) The front page shows that the device temperature grade is -40C to 125C but the Tjmax is 150C. Can you clarify?

(3) How can I calculate the quiescent current when Iout is 3mA? (is it 45uA?). There are multiple plots provided in the datasheet but I am confused about which plot to refer.

I am hoping you can help.

Regards,

Marvin

  • 0
    TI__Genius 12511 points

    Hi Marvin,

    1

    Yes, there are specific word choices that we make to show the difference. While the LM2936Q can work at 60V as stated in section 9, there are concerns with performance, in 7.3.1 it states the device is "fully operational" meaning that all EC table specs can be hit with a VIN up to 40V, however exceeding this voltage, and going from 40v-60v for the non H device, you will begin to see other concerns and problems with the operation of the device, specifically called out in section 9 is a VOUT short-circuit fault causing the device to be possibly permanently damaged during this condition. So it is not incorrect it can operate, it is just you cannot expect EC table performance when the device is taken away from the ROC table performance by going above 40V in.

    2

    150C is the abs max, meaning the device operates within -40 to 125, but can survive conditions beyond the point at which we recommend. Just like the first answer I gave where you can push the device above the recommended operating, once you exceed this, the device can still perform but it begins to risk being damaged and is no longer operating under TI's recommended operating procedures.

    3

    Yes, there are a few plots to try and show various ways that Iq can change. for Iout 3mA condition we can approximate it to be in between 40uA - 150uA. One thing that will have an effect is shown in Fig 3 and Fig 6 being close to dropout can cause Iq to increase by up to 60%. in Figure 7 we can see 200uA is for the IOUT of 10mA, and with your lower IOUT condition this will decrease. 40-60uA is a good approximation of what you might see for your specific condition

    Regards,

    John