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LM339: Please help to review the sch with post-PCN device

Rannie Zhou
Expert 3170 points
Part Number: LM339
Other Parts Discussed in Thread: LM239, , LM239A

Tool/software:

Hi Team,

Recently we sent the PCN for LM339: LM239ADR_Rbull_PCN_20231219002_1_Change_Notification.docLM239DR_PCN20231016006.1_Change_Notification.docLM339DR_PCN20231016006.1_Change_Notification.doc. ctm is testing the post-PCN device to see whether the PCN will influence their design. To help their test, could you please help to review below sch and provide the suggestion on whether these sch will be influenced by PCN?

sch1:

sch2:

sch3:

BRs,

Rannie

  • 0
    Guru 302700 points

    See section 3 of the Application Design Guidelines for LM339 Comparators.

    The quad device (LM339/LM239) does not change its behaviour, not even when both inputs exceed the valid input voltage range.

    But if you ever want to use the LM339B, this might matter. Please specify the comparators' power supply in schematics 1/2, and the input voltage range in all schematics.

  • 0
    TI__Guru 56146 points

    Hello Rannie,

    As Clemens mentioned, please describe the expected input voltage levels (i.e: BUSP_COM, INV_x, Flycap).

    The LM339 family input range is limited to Vcc-2V. The supply voltage for the first schematic (U21B) is not clear. The supply voltage must be more than 2.67V+2V=4.67V (5V). If it is less than 5V, then there may be a difference between the PCN devices due to the "both inputs over" behavior (section 5.8 of appnote).

    Also, we discourage adding capacitance to the non-inverting node when hysteresis is being applied (C196). The cap is pretty small (220pF) and probably will not cause any issues (assume it is intended for EMI filtering), but just want to bring that to your attention (appnote section 5.11).

  • 0 in reply to Paul Grohe
    TI__Expert 3170 points

    Hi Paul and Clemens,

    Thanks for your clarification, I will let ctm check their input voltage range and see whether the input range exceeds the Vcom range(V-~V+-2V).  BTW, I would like to double check with you: the input voltage is the value measured on the inverting and non-inverting input terminal, right? this voltage should in the range of common voltage.

    Clemens Ladisch said:
    The quad device (LM339/LM239) does not change its behaviour, not even when both inputs exceed the valid input voltage range.

    Ctm is using LM239A, how about the behavior of LM239A?

    BRs,

    Rannie

  • 0 in reply to Rannie Zhou
    Guru 302700 points

    Yes, the input voltage is the voltage at any input pin.

    LM239A is just a better selection of LM239.

  • 0 in reply to Clemens Ladisch
    TI__Expert 8220 points

    Hi Rannie,

    Please reply to this post if there are any further updates.