LMR14050-Q1: Enable/Disable

Joshua Japitan

Part Number: LMR14050-Q1

Hello, can I use this circuit to enable/disable the LMR14050-Q1 through its enable pin? Basically when RESET_SIG is low, Q3 turns off. Do I have to put a pull-down resistor (R6 here) between the enable pin and GND?

8 months ago

0 Marshall_Beck 8 months ago

TI__Mastermind 35170 points

Hello, if the circuit you have is in-active and has a high mpedance, then the IC's internal pull-up with pull EN high keeping the device active. If you leave the pin floating the pin should be pulled high, so you would want a pull-down to de-activate.

Are you using this for an inverting output application? We have a simple level shifter circuit in the appnote link below.

https://www.ti.com/lit/an/snvaa63/snvaa63.pdf?ts=1712758520621&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPSM365R6

0 Joshua Japitan 8 months ago in reply to Marshall_Beck

Prodigy 20 points

So all I need to do to disable it is just pull the EN pin to GND? Below is a sample circuit on how the RESET_SIG is produced. Would it be better to connect RESET_SIG to the EN pin to disable the buck converter?

Maybe I should add a 10k resistor between VIN and EN pin to make sure that RESET_SIG that is connected to EN pin is one of 2 states, +24V or GND. What do you say?

0 Marshall_Beck 8 months ago in reply to Joshua Japitan

TI__Mastermind 35170 points

hi, I haven't done an implemtation with a push button.

You need to ensure that you can pull EN above or below its threshold to active or deactivative the device. That is my recommendation.

I put the threshold value below from the EC table.

0 Joshua Japitan 8 months ago in reply to Marshall_Beck

Prodigy 20 points

Would this work? It is basically the previous circuit that is now connected to the LMR14050-Q1. I cropped the other components out of the picture.

+1 Marshall_Beck 8 months ago in reply to Joshua Japitan

TI__Mastermind 35170 points

Hi, it looks like you are on the right track. I would recommend validating on the EVM or in a simulator tool to make sure it works before finalizing the design.

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LMR14050-Q1: Enable/Disable