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TPS55332EVM: TPS55332EVM

Aslam Shaik
Prodigy 60 points
Part Number: TPS55332EVM
Other Parts Discussed in Thread: TPS55340, TPS55340-Q1, TPS55332-Q1

I have tested the EVM with 1MHz and 2MHz frequency settings, with input voltage range from 6V to 25V and output voltage=36V, with load from 50mA to 500mA.

The issue i observed is given below:

1MHz:

Vin                    Io                        Observation

6V                     50mA                  Converter working

6V                      70mA                   Shutdown

10V                     50mA                Working

10V                     100mA                Working

10V                     200mA                Working

10V                     225mA                Shutdown

13V                     50mA                Working

13V                     100mA                Working

13V                     200mA                Working

13V                     300mA                Working

13V                     360mA                Shutdown

25V                     50mA                Working

25V                     100mA                Working

25V                     200mA                Working

25V                     300mA                Working

25V                     500mA                Working

25V                     860mA                Shutdown

For 2MHz:

Vin                    Io                        Observation

6V                     50mA                  shutdown(Fluctuating/Ringing)

10V                    50mA                   Shutdown

13V                    50mA                   Working

13V                    100mA                   Working

13V                    200mA                   Shutdown

25V                    50mA                   Working

25V                    100mA                   Working

25V                    200mA                   Working

25V                   300mA                   Working

25V                    400mA                   Working

25V                    500mA                   Shutdown

My question is:

1. For what frequencies the EVM board will work.

2. Why the board is not working for 1MHz at input voltages 6V to 25V and Loads for 50mA to 500mA

3. There is no webbench available for TPS55332 to simulate the circuit with our requirements.

4. What are the changes to be made in order to make the board work for higher frequencies.

5. I know that for a given frequency and Ton, the input voltage range is restricted, but even for the input voltage, those are within the range the converter is not working for full output load range from 50mA to 500mA. Why?

6. Why the shutdown behaviour is observed, whether it is due to inductor power dissipation exceeding or any other reason, please describe.

The image for 6V, Io=65mA, 1MHz

The below image is for Vin=10.5V, Io=200mA, 2MHz

  • 0
    TI__Mastermind 40080 points

    Could you please share the sch with us so that we can check the parameter?

  • 0 in reply to Helen chen
    Prodigy 60 points

    www.ti.com/.../slvu319.pdf

    The TI link is given above the image

  • 0 in reply to Aslam Shaik
    TI__Mastermind 40080 points
    Please adjust the value of R8 and R11. when Vo=36V, and if R8 and R11 not changed, it trigers Vo UVP. increase the value of R11. Why do you select TPS55332, TPS55340 is also fit for your application.
  • 0 in reply to Helen chen
    Prodigy 60 points
    1. The Eval Board is not selected by us, it is selected by our client and we are validating the same.
    2. I am not sure what your trying to explain with the Vo UVP.
    I have configured the Vo, with the R2, R9, R7 values to Vo=36V, i have not configured the R8 and R11 values(i think they are set for Vo=25V as per the EVM), but still i have given a tolerance to Vo from 25V to 36V for UVP. I think this does not affect my operation.

    My question is what is the Minimum input voltage and what is the typical load for the minimum input voltage??( For both 1MHz and 2MHz)
    In detail:

    1. Need clarification on what is the minimum input voltage, and whether this minimum input voltage will work with all the loads from 50mA to 500mA. If not please mention the range of input voltage and range of output load for which the converter will work for.

    2. Why the shutdown behavior is observed in the plots attached in the previous posts. and the observations provided in the previous posts regarding the shutdown behavior with respect to the input voltage and Load??

    3. For what frequencies the EVM board will work.

    4. There is no webbench available for TPS55332 to simulate the circuit with our requirements.

    5. What are the changes to be made in order to make the board work for higher frequencies.

    6. I know that for a given frequency and Ton, the input voltage range is restricted, but even for the input voltage, those are within the range, the converter is not working for full output load range from 50mA to 500mA. Why?

    7. If there is any test data available with you, please share
  • 0 in reply to Aslam Shaik
    TI__Mastermind 40080 points

    1. this part could output 36V/400mA at Vin=6V, fs =1MHz condition by calculation.
    2. What is the frequency resistor value in your application in order to set fsw=1MHz, it should be around 100k ohm
    3. Please check the status of the RST pin to check if it is high or low when this error happens (change R11 to 6.04k ), if it has nothing to do with the RST pin , then there may some soldering problem exist.
    4. We didn't have the EVM on hand now,  need some time to get it. 

  • 0 in reply to Helen chen
    Prodigy 60 points
    Thanks for the reply,

    For the First Answer: You have mentioned that it could output 36V/400mA at Vin=6V, fs =1MHz condition by calculation.
    Whether it will work for Min. Load to Max. Load 50mA to 400mA with Vin=6V and Vout=36V for 1MHz.???
    From the above observations: For 1MHz, Vo=36V it has been observed that
    For Vin=6V, after 50mA of Load Shutdown is observed
    For Vin=10V, after 200mA of Load Shutdown is observed
    For Vin=13V, after 300mA of Load Shutdown is observed
    For Vin=25V, after 500mA of Load Shutdown is observed
    Please explain this behavior, is this behavior depends on the RST and RST_TH values and status??

    For the Second question: Yes the RT Resistor is adjusted to 100K

    Whether the circuit will work for 2MHz with RT=~50K, Please confirm??
    From the above observations: For 2MHz, Vo=36V it has been observed that
    For Vin=6V, For Min. Loadalso , Shutdown is observed
    For Vin=10V, For Min. Load also, Shutdown is observed
    For Vin=13V, after 100mA of Load Shutdown is observed
    For Vin=20V, after 300mA of Load Shutdown is observed
    Please explain this behavior, is this behavior depends on the RST and RST_TH values and status??
  • 0 in reply to Aslam Shaik
    TI__Mastermind 40080 points

    The shutdown is abnormal, there should be some error. did you check the soldering on the EVM board?  the main reason cause this problem  is soldering problem, by the way please check the status of the RST together with the Vo and send the waveform to me .

    This EVM board is new to us. We'll got the EVM at the middle of Jan.

  • 0 in reply to Helen chen
    Prodigy 60 points
    We will check the RST along with Vo, and let you know.
    I need confirmation from TI that this board will work for both 1MHz and 2MHz also with Vo=36V and current upto 400mA. Please confirm??
  • 0 in reply to Aslam Shaik
    TI__Mastermind 40080 points

    It's at the boundary of the 36V/0.4A  output capability when Vin=6V at fsw=1MHz.  Please short the diode D2 and inductor L1 to make the efficiency higher and be sure the voltage at the L2 (Vin) is 6V .

    I'll test the EVM board once I  get it.

    Suggtest you use TPS55340-Q1, this aprt is much cheaper than TPS55332-Q1.

  • 0 in reply to Helen chen
    Prodigy 60 points
    Whatever you have mentioned is for 1MHz, i hope the same applies to 2MHz also with the same ratings. I mean that this board will work for 2MHz also with Vin=6V to 25V and Vo=36V and Io=400mA.
    Our main concern is that this board will work for 2MHz also. Please confirm?
  • 0 in reply to Aslam Shaik
    TI__Mastermind 40080 points
    the efficiency in the 2MHz condiiton will be lower than that of the 1MHz condition. I need to check on the EVM board. Please wait some time.