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LM2596 recommended capacitor and inductor

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Xenobius

Xenobius

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Understanding terms found in datasheet

Hi all,

I am reading this datasheet and I came across some terms which I do not understand
LM2596 datasheet


  • What is Hysteresis ?
  • What is Capacitor ESR?
  • What is the code given to inductors (such as L38)

Thanks so much
X
 

Hi all,

I have a switching power supply rated 12v and want to use the LM2596-5V (not ADJastable version) to get 5V. Datasheet here. My question is about the input and output capacitors and inductors.

On page 1 of the datasheet it seems my answer is there. 470uF input and 220uF output with 33uH inductor (that can take the amperage needed which is around 2A) however further down the datasheet I get confused...

Inductor:
On pages 19 and 20 I get lost in what I actually need as an inductor. I figured either 33uH or 68uH but I am not sure.

Capacitors:
On page 23 Table 3 for fixed voltage (like in my case) it says that the output capacitor for 2A (I am using through hole and nichicon capacitors) is 180uF/35v. So should I do 220uF ? 180uF ? Can I use 2x 100uF 50V in Parallel as I do not have nichicon 180uF

More details about my application if it helps:
I have a circuit which requires 5v for most things and 3.3v 170mA for an ESP WiFi module. According to datasheet the ESP needs at most 170mA when transmitting. Average around 100mA.

I have a nextion lcd display which needs 500mA 5v, I have a 74hc595, an 8port relay board (JQC-3FF-S-Z) which powers up all 8 relays from 5V and finally an Arduino Nano. I estimated I will need around 2A 5V and I will use an AMS1117-3.3V also from the 5V. The LM2596 is rated for 3A so I will use a big heatsink on it. Also NOT ALL the relays will be on at the same time ever maybe at most 3.

Thanks :)
 
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Re: Understanding terms found in datasheet

ESR - term explained in datasheet paragraph 9.2.1.2.2
Hysteresis - used related to undervoltage lockout thresholds, schmitt-trigger function, see e.g. https://en.wikipedia.org/wiki/Hysteresis#Electronic_circuits

Inductor codes - I-V ranges referring to figure 27 to 30
 
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