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TPS709: TPS709

Brad Ketner
Prodigy 40 points
Part Number: TPS709
Other Parts Discussed in Thread: TPS7B69, TLV704, LP2985

Hello,

  We are using TPS70950DBVR in our PCB and our max input voltage is 24v. However, we are having random issues with the board burning out due to this component. On our schematic it is U1. Any incite on what the cause could be?083-1000-Rev3.0 No Freeze Control Board Assy Drawing.pdf083-1001-Rev3.0 No Freeze Control Board Schematic.pdf083-1000-Rev3.0 No Freeze Control Board BOM.pdf 

  • 0
    TI__Genius 10460 points

    Hi Brad,

    The maximum recommended operating voltage for the TPS709 enable pin is 6.5 V.

    Since the TPS709 in your application has an input voltage of 12 V typical and 24 V max, you should not be tying EN to IN. Based on the schematics you have provided, it looks like there are no other rails that can be used for an enable signal. You may have to add one or use a voltage divider at the regulator input to ensure that the enable pin voltage is always 6.5 V or lower. 

    Thanks,

    Gerard

  • 0 in reply to Gerard Copeland
    Prodigy 40 points
    Is there another part that would work for our current situation?
  • 0 in reply to Brad Ketner
    TI__Genius 10460 points

    Hi Brad,

    The TPS7B69 would be suitable to my knowledge of your application. It supports up to 40 V input, up to 150 mA load, has a fixed 5 V output version, and comes in the SOT23-5 package. It does not have an enable pin so there is no need for more components. If you have any additional performance requirements you can do a parametric search of TI's LDO portfolio on the TI website here:

    Thanks,

    Gerard

  • 0 in reply to Gerard Copeland
    Prodigy 40 points
    We need at least 12.5 v in where as the current part is only 6.5v? It doesn't look like the part recommended works either?
  • 0 in reply to Brad Ketner
    Prodigy 40 points
    Sorry out and en, where the current part is 6.5v we need 12.5v......
  • 0 in reply to Brad Ketner
    TI__Genius 10460 points
    Hi Brad,

    I apologize for making a mistake in my earlier post. The TPS709 enable pin cannot be used with a resistor divider. If you do not require the enable functionality, the TPS709 will regulate normally with EN left floating as the pin is pulled up internally to 6.5 V. Another option if you do not require enable functionality is the TLV704, a wide input, low quiescent current LDO that comes in the SOT-23 package.

    If you do require the enable functionality, the LP2985 is a good option if you can ensure that the maximum input voltage does not exceed 16 V. It has the same pin-out and load current capability as the TPS709, and there are no problems with tying ON/OFF to IN.

    Thanks,
    Gerard Copeland