Part Number: TPS24751
I am trying to power a large LCD 12V/8A(nom) LCD display from the output of the TPS24751 circuit.
The LCD can have as much as 26A in-rush current when the backlight powers up.
This is over an approximate 3ms period.
Would it be prudent/advisable to change/set the Dv/Dt rise-time on the output by adding the RC to the Gate control output pin of the TPS24751?
If so, what values would you recommend?
Thanks in advance.
Thanks for reaching out!
The attached app note explains about the selection of Cgate to control inrush current. Please go through it and revert back for any further queries.
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In reply to Rakesh:
Hi Rakesh, Sorry for the delay in replying. I have now followed the suggested details in the app note, and have it working.....nearly :) The issue I now have is that, if the load is connected to the output, and I then enable the eFUSE (EN = high, > 1.35V), the eFUSE shuts down (goes into hiccup mode). However, if I leave the load disconnected, enable the eFUSE, and then connected the load it's fine!!! I have tried various in-rush values, but this does not seem to solve the problem. The load draws an idle current of 7A but has an in-rush current up to 26A for 3ms. Any suggestions? Thanks.
In reply to Clayton Whitehead:
Hi Rakesh, Thanks for the quick response. I will get the test waveforms for you. In the meantime, just to let you know, the schematic is the same as for the datasheet except for the following:- 1) We are using a TTL signal on the EN input (having isolated it from the OV circuit and re-configuring the resistors for 5V instead of 12V. 2) We are using the Blocking FET as per Fig. 46 in the datasheet. Output capacitance is 470uF with diode across it (same as for Demo board) One question, when the datasheet refers to output capacitance (Cout), are we talking only of the eFUSE circuits output capacitance (470uF in this case), or do we need to include any load capacitance as well? Unfortunately, the datasheet does not appear to make this clear. If this is the case (need for including load capacitance), what is the best way of ascertaining this, as the load I am driving is a large Frame 12V/8A monitor and the datasheet for it does not give this information? Thanks for your help with this.
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