HI team member
When EN is disabled, VOI1 of TPS65140 ouputs nearly VIN by boost DC/DC configuration (VIN -> Inductance -> diode -> VO1).
This means LCD panel 's AVDD is applied VIN(5V) vorlage during EN is diabled,
*Have you ever heard this cause some damage for LCD panel ?
*Have you ever experienced this cause some trouble for start up ?
*To cut off this path, would you pleae let me know a circuit ?
best regards K.Kanao
Hello Katsuhiro,
The path from VIN to VO1 over the diode is a natural characteristic in a boost-converter. I do not quite understand why would that cause damage to the LCD panel as the source driver has to withstand VO1.
If you need to isolate the input from the output you can use a transistor that can be controlled either by the Power Good signal of VO1 (PG-pin) or by an external Enable Signal (EN-pin).
If you use the PG signal of the device and connect EN to VIN then the boost converter ramps up as soon as VIN is above UVLO. The switch T3 will close as soon as the boost converter has reached its power good (PG), see circuit below:
But you also can use the external enable signal:
I have attached both TINA files.
Let me know if you have any more questions.
Best Regards.
ilona Isolation+InrushLimiter_EN.TSCIsolation+InrushLimiter_PG.TSC
