LM2576 and conversion 24VAC to 4VDC for GSM module

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Hi boys,
please, can you help me? I need create design of power supply for GSM module SIM900. I found some catalog schematic of LM2576 ADJ as STEP DOWN from 12VDC to 4VDC. It's ok, but I need step down converter from 24V AC. Is good idea to use catalog circuit with diode bridge in input? Which solution do you suggest? Diode bridge or simply use of one diode - for example 1N4004 and capacity 220uF / 50V?
I need power supply with peak current 2A max and supply with no interferences.

Thank you for some help,
Petr
 

hey,
1> use 12o12 center tape step down transformer.
2> use 7812 ic =give +12v dc
3> refet ckt diagram i have uploaded
 

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Thanks for reply, but it's absolutely BAD. SIM900 need 3.6 - 4.2V (as LiIon voltage). I need small design, without any transoformers, etc.
I need power supply circuit for use SIM900 with 24VAC or 12VDC supply. Catalog circuit of LM2576 is ideal for 12-40V supply, but it is for DC voltage. My problem is not about usage of stepdown, but about how can I made AC to DC conversion with good parameters and solution which is usable with DC power source and common GND too.
 

The LM2576 is a switching regulator and is suitable for use with a SIM900.

To use it with an AC input use a bridge rectifier as per the circuit already posted here.

With the bridge rectifier your input can be either AC or DC.

Cheers.
 

no what i told is including adapter.u must be using adapter and then feeding it to power supply.thats what i am saying.tranformer is a part of adapter.u can omit the transformer part in my diagram.i had used sim900 in my major projects
 


Hi
Of course it is a good idea to use LM2576 , why not ?
Best Wishes
Goldsmith
 

hi every one !
i have to make power supply for gsm sim 900, and i have tried this with lm2576 regulator, but i failed...i have used the basic power supply design for lm2576
http://e2e.ti.com/support/power_management/simple_switcher/f/858/p/255499/1039477.aspx#1039477 but at the output i dont get 5 volts, i get the output voltage equal to input... i dont have IN 5822, any schottkey diode so i am using simple diode , and inductor of some different value, so i
guess becoz of these two i dont get the desired output,, am i ri8??can i use simple diode or zener diode instead of schotkey, plz help me out in this
 

Just dealing with similar source.
I guess I will use this solution
 

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