• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 63 subscribers
  • Views 596 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS22963 off current

Toralf Popp
Prodigy 90 points
Other Parts Discussed in Thread: TPS22964C, TPS22963C

Hi everybody

We use the TPS22963 in a circuit board as a power path switch for external devices. We measure (at a lot of pcb's) a slow increasing output voltage (up to 2 V OUT@3V IN, switch is OFF ) even if a 1k resistor is connected at the output. We also measured at a few brand new parts (at the reel) a DC resistance of less than 500k between IN and OUT. Another test results in a lesser resistance (les than 30k) after heating only the part for 10 sec. 300°C. Is ther a known issue relating these phenomenons. The circuit must be OK because the first series (100 pcs.) of the same pcb working well (100 %).

Thanks for answer

  • 0
    TI__Genius 15760 points

    Hi Toralf,

    Thank you for reaching out to us. Because the TPS22963C does not have any QOD (the way the TPS22964C does) the output will be left floating when the device is turned off. Adding a pulldown resistance of 1kΩ should pull the output down.

    A few questions:

    1. When you say the device is heated at 300°C for 10 seconds, are you referring to while the device is operating, or when it is on the board with no power applied?
    2. What happens when these units are turned on? Does the device behave normally (low on-resistance and VOUT = VIN)?
    3. How is the device being turned off? Is the enable pin pulled down or left floating? A floating enable pin does not guarantee a fully off device.

    Thanks,

    Alek Kaknevicius

  • 0 in reply to Aleksandras_Kaknevicius
    Prodigy 90 points

    Hi Alek

    Thanks for reply.

    1. We heated them up outside of the PCB (in the reel) to test thermal behavior / change of behavior

    2. Yes, at turning on it behaves normally

    3. Turned off by ENABLE = LOW (tested also with short to GND), then we can see theat the voltage slowly increases until the ciruit starts oscillating. Turning OFF in the circuit takes a few seconds, but will never reach 0V. (opposit to turning ON)

    With the most (perhaps defective) parts we can see a voltage of app. 0.5 .. 2.3V even if the ENABLE is LOW and a resistive load of 1k. We heve checked a few reels with different date codes and we assume that there are some major differences. One reel has about 500k between IN and OUT,. Another reel has app. 5..7M at the same pins. We measured all parts directly at the reel.

    What the strange thing  ist that the first (good) series (100 pcbs)  the output voltage goes immediately to 0V when the ENABLE is LOW.

    We assume that the new parts are running outside of spec.

    Kind regards

    Toralf

  • 0 in reply to Toralf Popp
    TI__Genius 15760 points

    Hi Toralf,

    Thanks for the information.

    It looks like we have not had any returns or issues of this type with the TPS22963C in the past.

    Is there any possibility that the device is being subjected to voltage transients or current spikes which exceed the max rating for the device (6V/3A)? Also, can you please provide the information for the reel which is being measured down to 500kΩ? In general, what is the failure rate for this issue (Every device on a specific reel, 1% of devices, etc.)?

    Thanks,

    Alek Kaknevicius