I used a buck converter (Lm2596) to provide enough power to my nrf24l01+ pa lna cause the 3.3v pin from arduino cant handle it.
So I used a buck converter (http://www.baudaeletronica.com.br/media/catalog/product/l/m/lm2596.jpg). I connected the IN of the module to my power wallet (which provides 12v) and tested the OUTPUT with a multimeter till I get 3.3v in the OUTPUT. After that I connected my nrf24l01+ to the OUTPUT.
Finally I connected both grounds (from the INPUT and OUTPUT) cause I always hear in the internet "connected all grounds together". As soon as I did this my nrf24l01 became very hot and does not work anymore. Connecting the grounds in this case, when using a DC-DC converter is not allowed?
In the real world... pins marked GND in the same context are all "equivalent" but you should never need to connect the GNDS on the same board... they should be redundant.
But, the picture you showed did not exactly indicate that there were 2 GND pins there.
In typical LM2596 designs, the ground IS common for input and output pins. A quick visual inspection of the board says to me... maybe not on that design... but hard to tell. I honestly don't think what you claimed you did was the issue. The standard design for that chip would have those pins marked (-) at the same potential.
On a side note: Sometimes these will produce a whine... just wait till you are 45 years old... you will no longer hear it.
With your nrf module disconnected, does the buck converter seem to function properly? What is the output voltage with the two grounds connected together and then not connected together?
The GND were connected toghter with GND of arduino too. They were all together. I cant measure the voltage of my buck converter cause it does not work anymore just like the nrf24l01. I cant really understand what went wrong...
@septillion you are all right, I did exactly that except that I was powering my arduino using USB and not VIN, but I connected all the common GNDs.
It was everything working fine without connecting IN- and OUT- together. So I decided to connect it together in hope that I was doing exactly what people say "connect all grounds together", and after that my nrf24l01 (the chip on top of it) became really hot and stopped working. It was working perfectly before I connect gnds together...
batata004:
Yeah... sad to know that cause I really dont know what I did wrong
I apologize for the thread necromancy but I was wondering if you figured this issue out. I connected a buck converter to an NRF240l and the radio module promptly smoked.
I had checked the outgoing voltage using a multimeter and it was 3.298 volts.
As an experiment I tried with a new module at 3v and the radio still went kablooie.
Here's a photo of my setup:
That's 9 volts in from a bench supply into the buck converter and as you can see the voltage out is less than 3 volts.
On the previous attempt, the voltage was extremely close to 3.3.
In both cases, the module was hooked up to the Arduino. The arduino was being powered by the same bench supply.
And in both cases the radio module was smoked, rendering it non functional.
using crocodile clips for wiring up power supplies is.
It only takes a slip and a ground is disconnect and things can go mad. You have to solder connections securely when playing about with these things.
Grumpy_Mike:
using crocodile clips for wiring up power supplies is.
It only takes a slip and a ground is disconnect and things can go mad. You have to solder connections securely when playing about with these things.
Well, yeah, but in this case it's more to show that the voltage coming out of the buck is below the voltage for the component, and that it was at 3.3v previously, and yet the module smoked (When it was connected via wires instead of alligator clips)
That's why it's important to have spare components on hand. If you suspect that the converter is the issue, then put in another nrfL01+ and see if everything works nicely. If it happens again...... and if you have done all you can to ensure that wires or connections aren't getting broken (or inadvertently slipping onto something else), then set up a measurement device that keeps monitoring the voltage output of the voltage converter during operation. Eg..... if over-voltage condition is detected automatically, then start logging (recording) the voltage ..... versus time.
bhinmantx:
It appears this is an issue of waaaay too much juice. The buck converter is giving me 3 amps, and at 3 volts that's... what, 9 watts?
Please correct me if I'm wrong, but according to the data sheet the max power dissipation is 60mW
That explains why my radio module turned into smoke and disappointment, right?
Not at all. The power rating is a value associated with how much output power the converter module is "able to" provide to whatever it is supplying power to. Eg.... a 9 Watt rating means.... if the supply voltage is 3 Volt, then the supply can drive devices where the output current (from this supply) should not be allowed to become significantly higher than 3 Amp..... otherwise supply could run into some issues, like cutting in and out.
It doesn't mean that is the amount of power that the module dumps into whatever it is supplying.
bhinmantx:
It appears this is an issue of waaaay too much juice. The buck converter is giving me 3 amps, and at 3 volts that's... what, 9 watts?
Please correct me if I'm wrong, but according to the data sheet the max power dissipation is 60mW
That explains why my radio module turned into smoke and disappointment, right?
It is very wrong.
It is mathematically and physically impossible for a power supply to provide a constant voltage and current to arbitrary loads, because different loads will have different I-V characteristics. For example, 1V @ 1A is impossible through a 10 ohm resistor.
So most power supplies will regulate one of those parameters to be constant, allowing the other to vary depending on the characteristics of the attached load. The vast majority of power supplies are constant voltage. They regulate the voltage to a constant value, and the current varies depending on the attached load. The current spec provided on CV power supplies is a maximum rating. It is the maximum the supply can safely provide, but the actual current value can be anything from 0 to infinity.
Note carefully that the supply will not necessarily limit itself to stay below the rating. If a 4A load is attached to a 3A power supply, it might very well provide the full 4A of current, all the way until it breaks from over-stress.
Constant current supplies are the opposite. They regulate the supplied current to a constant value, and vary the applied voltage as the load requires. The are much less common than CV supplies, and are mostly used for driving high power LEDs. Like current before, the voltage spec of these is a rating, and the supply might not necessarily have circuitry in it to prevent the voltage from exceeding the rating.
