Enabling and Disabling a switcher using Microcontroller Circuit Review

Thread Starter

hoyyoth

Joined Mar 21, 2020
309
I am using TPS62160QDSGRQ1 in my design. I need to enable and disable it using a microcontroller GPIO and it voltage is 1.8V.
Below is my circuit.
1708490878785.png
My design calculations are are given below.
1708490913449.png
May I know your comments
 

MrSoftware

Joined Oct 29, 2013
2,202
What voltages will your microcontroller pins allow? Assuming your microcontroller is a 1.8V device, the DS_LDO_1V1_EN pin is going to see 5V, and that might be a problem. Check your data sheet on that.

Second, assuming that first part is OK, you're cutting it a bit close with the voltages on the EN pin. If this is for production, remember that not all parts are perfect and you may not get exactly what you're expecting for voltages on the EN pin, so a wider margin might be safer. I only skimmed the data sheet, but going by table 7.5 it appears the EN pin has some hysteresis, meaning it may turn ON at 0.9v, but may not turn back OFF until 0.3V. You're expecting to be able to pull EN down to 0.165V, on paper it works, but when you throw in parts variability you may have some fallout.

You can solve both problems by replacing your R847 with a switch of some sort that has 5V tolerance but can be triggered by 1.8V input. Maybe a simple transistor will work, there are multiple ways to solve it.
 
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