View Full Version : Texas Instruments TPS57160 Enable Pin via P-Channel Open Drain Output

November 3rd, 2016, 02:22 AM
So I have a module that supposedly has a P-Channel Open Drain Output (INH on Infineon TLE6251-2G) and I am trying to interface that with the EN (Enable) pin of the Texas Instruments TPS57160-Q1(http://www.kynix.com/Parts/3594306/TPS57160-Q1EVM.html)Step Down Converter.

The TPS57160-Q1 activates if the EN pin is at a voltage above 1.25V and has a "pullup current source" (whatever that means) in order for it to be activated when the EN pin is left floating.

Now the TLE6251-2G's INH active output (means the Step Down converter is to be activated) is VS=36V in my case. When the output is "disabled", the INH is left floating.

Now the question is: How can I interface the two pins? I only have the 36V rail and GND available and it should be ultra low power in the disabled state.

If I add a pulldown resistor at the INH pin and connect that to the EN pin of the TPS57160-Q1, I should have it properly disabled but I exceed the absolute maximum voltage rating of the EN pin by far. (36V vs. 5V) To get around this, I thought of a simple voltage divider to get the voltage to a healthy range. Furthermore, I don't really know how the TPS57160-Q1's EN pin reacts to a pulldown resistor with its "pullup current source" (This is my main problem in creating a proper interface)

Thank you in advance!

November 3rd, 2016, 10:22 AM
How about a zener diode to clamp the voltage to the appropriate range?