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TPSI3050-Q1: Designing with TPSI3050-Q1

Sv
Intellectual 635 points

Part Number: TPSI3050-Q1
Other Parts Discussed in Thread: TPSI3050

Tool/software:

Hello Team,
We are using the IC TPSI3050-Q1 in one of our products.

The attached is the schematic of the same.

The device is working in 2 wire mode,

The GPIO_275 is from a 3.3V GPIO pin of a controller and when we assert the pin, we are getting a 12V at the EN pin of the TPSI3050-Q1.
But still we are not getting +10V across TP11 and TP9. But instead we are getting +3V only.

But sometimes we will get +10V across these test points and the FET will turn ON.

1). What could be the reason for this?.

2). Is there any reason if we give 12V at the EN pin is the device is working in 3 wire mode?.

We have not given any voltage source or load at either end of the MOSFET. We are just checking the electrical resistance between the DRAIN of the MOSFET.

Looking for your reply.

  • 0
    TI__Intellectual 950 points

    Hello SV,

    Thank you for reaching out to our team on E2E. To answer you questions:

    1: Unfortunately, there is no clear answer to your problem with the information you have provided. Let's go through a few troubleshooting steps to determine the root cause. 

    Are you able to consistently replicate the issue where you see the +3V from TP11 and TP9? 

    If you remove R50 from the board, can you still reproduce the fault where you see the +3V from TP11 and TP9?

    When the device is faulting out, can you obtain an oscilloscope capture of the EN, VDDP, VDRV, and VDDH pins?  

    We are looking for a scope capture similar to the following: 

    2: The device may get stuck into 3 wire mode if the EN is pulsed quickly, as there may be some voltage across C33 from the last time the IC was enabled. 

    I look forward to your answer, and quickly getting your issue resolved.

    Regards,

    Jack Hemmersmeier  

  • 0 in reply to Jack Hemmersmeier
    Intellectual 635 points

    Hello Team,
    Thank you for your reply.

    1). Yes we are able to reproduce the issue. Also, we have tried to remove the 0E resistor (R50) and tried the same and still we are getting 3V across those test points in the multi meter.

    At the EN pin, we are getting 12V at the VDDP pin we are getting 4.3V, and at VDDH and VDRV pin, we are getting 3V.

    I will share the scope shot soon.

    Jack Hemmersmeier said:
    2: The device may get stuck into 3 wire mode if the EN is pulsed quickly, as there may be some voltage across C33 from the last time the IC was enabled. 

    OK. In 3 wire mode, what happens if we give 12V to the EN pin.

    In our application, we have almost 40 TPSI3050 ICs.

  • 0 in reply to Sv
    TI__Intellectual 950 points

    SV,

    With the OE resistor (R50) removed, there should be no load to pull down the VDDH rail. I am awaiting you scope capture to provide my next recommendation. 

    If the device were to be in 3 wire mode, it would not source power from EN, deplete the VDDP capacitor and the device may behave unexpectedly. 

    I look forward to your answer, and please feel free to reach out to me for a call to discuss this issue.

    Regards,

    Jack Hemmersmeier 

  • 0 in reply to Jack Hemmersmeier
    Intellectual 635 points

    Hello Team,
    Sorry for replying late.

    We have multiple TPSI3050-Q1 in our PCB and all are working in 2 wire mode.

    But the schematic is designed in such a way that we can validate the 3 wire mode as well.

    So we have a 0E resistor (DNP now) in the PCB from a 3.3V to the VDDP pin of the IC.

    Do to this, all VDDP pin of the driver ICs are shorted together and if we turn on only one driver, we will not get a voltage at the VDDH pin.
    when all are turned ON, this issue is solved.

    So if only one driver is turned ON in 2 wire mode, the EN pin will get 12V, the VDDP will get charged and thus the VDDP of all the driver ICs since all are connected together.

    And then if we try to turn ON the second driver, since its VDDP is charged to some voltage (4.3V) and EN with 12V, this driver is not turning ON.

    Will the device turn on when the VDDP is powered with 5V and if we give 12V at the EN pin?.

  • 0 in reply to Sv
    TI__Intellectual 950 points

    SV,

    To answer your question, no, this may damage the device. In 3 wire mode, if VDDP is 5V, then EN needs to be 5V to turn the device on. 

    Can you confirm that the schematic you initially shared has not changed? You have mentioned there is a way to drive the device in 3 wire mode. 

    Where you able to obtain the scope capture?

    Please feel free to reach out to me for a call to discuss this issue. Do you have an TI field applications contact?

    Regards,

    Jack Hemmersmeier 

  • 0 in reply to Jack Hemmersmeier
    Intellectual 635 points

    Hello Jack,
    Thank you for your reply.

    Can you please accept my friend Request/ or can you please share your email id?

  • 0 in reply to Sv
    TI__Expert 8971 points

    Hello Sv,

    Thanks for reaching out to our team on E2E, I remember supporting your schematic review for this project a year ago. Time goes by quickly. Blush

    If you are measuring 3 V on VDDH, it sounds like the TPSI3050 may be damaged.

    Were the TPSI3050s working at an earlier time but now are not? Did anyone apply >5.5 V to VDDP? This would damage the devices.

    Are you able to measure the current into EN? TPSI3050 in two-wire mode with RPXFR = 20 kohm should draw 6.7 mA on EN. So 40 devices normally would draw ~268 mA.

    Best regards,
    Tilden Chen

    Solid State Relays | Applications Engineer

  • 0 in reply to Tilden Chen
    Intellectual 635 points

    Hello Tilden,
    Thank you for your reply.

    No, we didn't apply any voltage greater than 5.5V at the VDDP pin since we are operating in 2 wire mode.

    But an option for 3 wire mode is also given in the schematic.
    The current is close to what you have said.

  • 0 in reply to Sv
    TI__Expert 8971 points

    Hello Sv,

    Thanks for your reply.

    Sv said:
    Do to this, all VDDP pin of the driver ICs are shorted together and if we turn on only one driver, we will not get a voltage at the VDDH pin.
    when all are turned ON, this issue is solved.

    Just noticed this. So what may be happening when you only turn on a single driver IC (TPSI3050) is that the TPSI3050 receiving 12-V is entering two-wire mode and outputting 4.6-V at VDDP. Since the TPSI3050s all have VDDP shorted together, they each see the 4.6-V and try to enter three-wire mode, pulling current and stealing power from TPSI3050 in two-wire mode. The first TPSI3050 is now unable to transfer the necessary power across to VDDH, resulting in only 3-V instead of 10-V.

    If you had a way to disconnect the TPSI3050's VDDP from the other TPSI3050 VDDPs, such as cutting the trace, that may fix the issue and cause VDDH to come up to 10-V again.

    Best regards,
    Tilden Chen

    Solid State Relays | Applications Engineer

  • 0 in reply to Tilden Chen
    Intellectual 635 points

    Hello Tilden,
    Thank you for your reply.

    Tilden Chen said:
    Since the TPSI3050s all have VDDP shorted together, they each see the 4.6-V and try to enter three-wire mode, pulling current and stealing power from TPSI3050 in two-wire mode. The first TPSI3050 is now unable to transfer the necessary power across to VDDH, resulting in only 3-V instead of 10-V.

    Initially, we also thought of the same. But, we measured the voltage at the VDDP pin and the voltage was above 4.5V even though all the VDDP pins are shorted together.
    Another interesting observation is that, if we turn ON all 39 drivers also, some drivers will not turn on properly.

  • 0 in reply to Sv
    TI__Expert 8971 points

    Hello Shibin,

    Thanks for your reply. Please disconnect the VDDPs from one another due to two-wire mode operation. We cannot guarantee how the devices will interact with one another as they all try to turn on. Some drivers may be turning on faster than others, resulting in the delayed drivers to attempt three-wire mode operation, receiving insufficient current, and improper turn on.

    For optimal two-wire mode operation, we also recommend ramping EN to greater than 6.5V in ≤1 µs when turning on the output and ramping EN to less than 2.0V in ≤1 µs when turning off.

    Otherwise, TPSI305x-Q1 can become stuck in-between logic states while the EN is in-between the maximum voltage (VIL_EN) recognized for a low-state and the minimum voltage (VIH_EN) recognized for a high-state. During this in-between state, the TPSI305x-Q1 tries to turn on the output but is not transferring enough power so the secondary supply hits UVLO and turns off the output. This process repeats until EN voltage is sufficiently high for power transfer to keep the output on.

    Best regards,
    Tilden Chen

    Solid State Relays | Applications Engineer