Noise in SMPS

[ejazbeyond]

hello, i am using a smps which give me 12v 2A, i am using this for powering my relay, acs756 current sensor and sim800, but converting voltages using 7805 regulator for current sensor and 2576ADJ buck converter for sim800.
i am concerned about placement of buckconverter should i place it on smps board or on sim800 board(we have designed a board with sim800,atmega32 and lm2576).
we placed LM2576 on gsm board because we think if we place it on smps board, noise will be added to it because we have to wired it to gsm in that scenario. so i want to know this thought process is correct or wrong?

 

[dknguyen]

I would place it in the SMPS board and filter it. The LM2576 makes plenty of noise on its own already so moving it off the SMPS board onto the GSM board away isn't going to protect the GSM from the LM2576's own noise.

 

[dr pepper]

You dont have much control of things with a monolithic reg, however sizing the inductor to make the circuit continuous might reduce noise some, and conducted noise can be tamed a little with a choke or filter circuit.