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TPS7A4701-EP: Enable pin

Part Number: TPS7A4701-EP

Tool/software:

Hi. I've used this part many times, always tying the enable pin (pin 13) to VIN. On a new application, I need to control it with a 3.3V signal (H= on, L = off). I saw that the minimum voltage V+EN(HI) for this pin is 2V, and despite feeding it 3.3V, it doesn't work. The description in the pinout table is not really very clear to me either. My VIN is 24V, and VOUT is 12V. Could you please help clarify if I can drive the EN pin directly from my 3.3V line, or if I need to add some transistor circuitry that my 3.3V line controls to feed VIN to the EN pin? Or if there's another way?

Many thanks

  • Hi Santo,

    The EN pin voltage cannot be higher than Vin (per the abs max conditions in the datasheet). Otherwise, driving EN with an external 3.3V should work just fine. You also want to ensure that the NR pin does not have leakage on the PCB (such as from flux or other contaminants). Contaminants on the PCB can lower the impedance from NR to GND which will act as a voltage divider from the internal NR resistor (and thus lower the reference or output voltage).  Clean the PCB with isopropyl alcohol and distilled water then dry and retest.

    If cleaning the PCB does not help and you are not violating the abs max conditions, can you please provide Vin, Ven, Vout and Iout on an oscilloscope plot to aid in troubleshooting?

    Thanks,

    Stephen