Hi,
I need to be able to switch a load (8v , 0.5A) on/off with a Teensy 3.2.
I was initially planning to drive a MOSFET with Teensy, which would turn the power on/off on a traditional regulator, like this one, but then came across a "smart" regulator (https://www.amazon.com/gp/product/B0758ZTS61/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1).
The neat thing about this particular DROK reg is that it has an "Enable" pin, which, if pulled to GND, disables the output. This is exactly what I needed.
I got it and started using it - and it seems to work fine, saving space and simplifying the design.
However, being a non EE, I have a tingling sensation that I might be risking to fry my Teensy.
I see two ways to wire this up, would really appreciate feedback on the "right" way.
#1. Connect some digital OUTPUT pin from Teensy to the "enable" port of the regulator (say via 1k Ohm resistor).
Now, when I drive the pin low - regulator turns off, when I DigitalWrite(1) - reg turns on. When Teensy is not powered - the regulator is ON by default (since "enable" pin is held high by the reg)
#2. Connect "Enable" port on the reg to the common GND (say via 3k Ohm resistor), and connect T3.2 pin to "enable" port on the regulator (say via 100 Ohm resistor).
Now, the reg is always OFF, unless I DigitalWrite(1) on the T3.2 pin that's connected to the "enable" port.
Both models work in practice, when I test them. I prefer #1 - as I would like to keep the regulator ON when Teensy is not powered.
The thing is, voltage between "enable" pin on the regulator, and the common GND is about 7v. (Again, if left un-grounded - the regulator is ON.)
When I ground the "enable" pin on the reg via multimeter - I see 60 micro Amps flowing from "enable" into common GND.
I suppose in the wiring model #1 - Teensy would have to be "sinking" that current. Is 60 micro amps safe to sink through a digital pin (say pin 13)? Will the fact that the reg's "enable" port is initially held at 7v pose some frying risks, or should I assume that the voltage will drop quickly and be under Teensy's safe limit? Am I even right being concerned about the voltage on an OUPUT pin?
In the model#2, I guess the same is true, most of the current is going to flow to GND through the digital pin on teensy, but will fact that there is resistor always pulling the "enable" pin to GND somehow make it safer?
Sorry if this sounds like nonsense, my intuition for Ohms law has gone the way of my hair.
Thanks!
I need to be able to switch a load (8v , 0.5A) on/off with a Teensy 3.2.
I was initially planning to drive a MOSFET with Teensy, which would turn the power on/off on a traditional regulator, like this one, but then came across a "smart" regulator (https://www.amazon.com/gp/product/B0758ZTS61/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1).
The neat thing about this particular DROK reg is that it has an "Enable" pin, which, if pulled to GND, disables the output. This is exactly what I needed.
I got it and started using it - and it seems to work fine, saving space and simplifying the design.
However, being a non EE, I have a tingling sensation that I might be risking to fry my Teensy.
I see two ways to wire this up, would really appreciate feedback on the "right" way.
#1. Connect some digital OUTPUT pin from Teensy to the "enable" port of the regulator (say via 1k Ohm resistor).
Now, when I drive the pin low - regulator turns off, when I DigitalWrite(1) - reg turns on. When Teensy is not powered - the regulator is ON by default (since "enable" pin is held high by the reg)
#2. Connect "Enable" port on the reg to the common GND (say via 3k Ohm resistor), and connect T3.2 pin to "enable" port on the regulator (say via 100 Ohm resistor).
Now, the reg is always OFF, unless I DigitalWrite(1) on the T3.2 pin that's connected to the "enable" port.
Both models work in practice, when I test them. I prefer #1 - as I would like to keep the regulator ON when Teensy is not powered.
The thing is, voltage between "enable" pin on the regulator, and the common GND is about 7v. (Again, if left un-grounded - the regulator is ON.)
When I ground the "enable" pin on the reg via multimeter - I see 60 micro Amps flowing from "enable" into common GND.
I suppose in the wiring model #1 - Teensy would have to be "sinking" that current. Is 60 micro amps safe to sink through a digital pin (say pin 13)? Will the fact that the reg's "enable" port is initially held at 7v pose some frying risks, or should I assume that the voltage will drop quickly and be under Teensy's safe limit? Am I even right being concerned about the voltage on an OUPUT pin?
In the model#2, I guess the same is true, most of the current is going to flow to GND through the digital pin on teensy, but will fact that there is resistor always pulling the "enable" pin to GND somehow make it safer?
Sorry if this sounds like nonsense, my intuition for Ohms law has gone the way of my hair.
Thanks!