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TPS62200: mixed up IC pins still works

Part Number: TPS62200


I made the mistake of mixing up the GND and EN pins of the TPS62200DBVR in my design, however the IC still works. It gets the "DCDC_EN" signal to its GND pin and the EN pin is directly connected to the GND plane as seen on the attached schematic. The "DCDC_EN" is on the same potential when active as the Voltage Input pin of the IC, so if I understand correctly when I mixed up the 2 pins, that means, whenever there is a "DCDC_EN" the GND pin is on the same potential as the Voltage Input pin meaning there should be no voltage between the IC's ground and input and the EN pin should be on negative voltage. Suprisingly the circuit works perfectly and it generates the required voltage despite of the fact, that the input voltage should be 0V. I observed the output signal via an oscilloscope and I haven't experienced any anomalies, everything works as if I haven't mixed up the pinout (I corrected it, and it works the same). The device which contains this circuit with the wrong wiring has been working for two months non-stop without any noticeable error. I already confirmed that the IC works, it is not the LDO which provides the voltage when more current is required beacuse it turns off when the DCDC_EN signal is active. Could you please provide an explanation why the TPS62200DBVR is working despite of that it is wired wrong and what behaviour should I expect from it?

  • Hello,

    Can you send the part of the circuit where DCDC_EN is tied up and a screen shot of the PCB layout? Because I don't see any possibility for the device to turn-on where EN pin is pulled to GND. Or maybe the layout is correct based on the device footprint.

    Best regards,


  • Hi,

    Unfortunately the problem is not in the layout. The DCDC_EN is tied to BAT+ through a MOSFET. The voltage of BAT+ is 3.72V.

    I disconnected the LDO by removing the D2 diode and I pulled the DCDC_EN to BAT+ permanently so the whole circuit is powered by the TPS62200 then I measured the VCC. Here are the results:

    When the circuit is in "idle" state:

    When more current needs to be drawn from the source:

    As you can see, the output voltage drops when current is drawn from the converter.

    In conclusion the TPS62200 provides a slightly higher output voltage than when its pins are not mixed up and it can still power the whole circuit.

    How is this possible?

  • Hello user,

    Can you provide the voltage waveforms of the following parameters with respect to pin 2 - GND pin of U2? This will help me understand what is happening to the circuit.

    1. VIN pin (pin 1 of U2)

    2. EN pin (pin 3 of U2)

    3. VCC

    Based on the waveforms above, the VCC is not regulating properly so there is an issue with the circuit. So you still need to modify the schematic and layout accordingly.

    Best regards,


  • Hi Excel,

    Here are the waveforms respect to the GND pin to U2:

    Pin 1 of U2 (Vin):

    Pin 3 of U2 (EN):

    The spikes are (at 0V) when DCDC_EN is active.


    Again, the drops are when DCDC_EN is active.

  • Hello User,

    First, VIN (pin #1 of U2) is 0V with respect to GND (pin #2 of U2) so the device is NOT operating. You can confirm this by measuring the voltage across SW pin (pin #5 of U2). If the device is working properly, then SW pin should be switching from VIN level to 0V with respect to GND pin. In addition, subjecting the EN pin (pin #3) with < -0.3V (above the absolute max rating) may result to device failure. It's possible that the voltage you see on Vcc is due to leakage current only.

    Finally, you need to revise your schematic diagram and layout specifically on EN and GND pins of U2.

    Best regards,


  • Hello User,

    If you don't have further query, I will close the thread. You can open the thread again by posting your questions.

    Best regards,