Tool/software:
Hello Team,
I came across the TPS259830LNRGE product for use in a project due to its current limiting feature and wanted to test it. To conduct tests with this product, I purchased the TPS25983EVM evaluation module and started experimenting.
My goal is to use a 12V power line with a 0.7-ohm load resistance at the output, ensuring it remains on for at least 50ms while drawing 7.5A.
I have conducted some experiments on this topic and have two questions:
1-Failure to Operate Properly at Room Temperature
The setup on the EVM board is as follows:
| J9 | Open |
| J10 | 210ohm |
| J6 | 1-2 Position |
| J11 | 1-2 Position |
| J4 | Open |
| J12 | 1-2 Position |
| R1 | 1M |
| R2 | 124K |
| J13 | Close |
| C3 | DNP |
| Vin Line | CAP AL,220 uF 35 V |
The setup is configured, and power is applied to the 12V line.
The load is connected using a switch.The oscilloscope capture is as follows:
(Continue with the details or attach the oscilloscope image)
- What is the reason for the peak observed at the initial startup on channel 3?
- Is the short on-time of the line caused by thermal shutdown?
- Could the peak observed on channel 3 trigger any protection mechanism, and how can this peak be reduced?
- How can I ensure that this line remains on for at least 50ms?
The current drawn from the line was increased slightly above 1 ohm by adding a 0.33-ohm resistor in series with the 0.75-ohm resistor, and the test was repeated. The capture is shown below.
As seen, no peak is observed, and the line remains on for approximately 158 ms.
Since the current is intended to be limited to 7.5A, the Ilim resistor value was set to 242 ohms, and the test result is shown below.
2-Failure to Operate Properly in Cold Test
The tests under this heading were conducted with 0.75 + 0.33 ohm resistors in series.
Several modifications were made to the EVM board, and a chamber test was conducted to observe its performance at different temperatures.
| J9 | Open |
| J10 | 242ohm |
| J6 | 1-2 Position |
| J11 | 1-2 Position |
| J4 | Open |
| J12 | 1-2 Position |
| R1 | 1M |
| R2 | 200K |
| J13 | Open |
| C3 | DNP |
| Vin Line | CAP AL,220 uF 35 V |
The test was first conducted at 65°C, and the results are shown below.
As seen, it operates for approximately 50ms.
Next, the test was conducted at -40°C, and it was observed that the system did not operate properly.
As seen, the line remained active for less than 4ms.
After observing this result, the temperature was increased by 10°C and tested sequentially at -30°C, -20°C, -10°C, and 0°C. There was no significant change observed. The line's on-time for each temperature was as follows:
- 3.627ms at -30°C
- 3.827ms at -20°C
- 4.227ms at -10°C
- 5ms at 0°C
-
If it is shutting down due to thermal shutdown, why does it behave this way in cold temperatures?
-
In general, what could be the cause of this behavior, and what solutions would you recommend?
Thank you in advance for your support.
Best regards,
Arslan.
