Hi,
I am using BQ24167 dual input charger IC & TPS2500 USB Boost converter in my charger design.
I am able to hear HUM sound from the system.(Mostly near Input section of TPS2500 )
Block Diagram:-
Circuit :-
While probing battery voltage (when Hum sound is resent) i am able to see max 560mV fluctuation on bat+.
Plot:-
Battery Signal levels for Samsung Galexy mobile load are,
Battery Spec:- 3.7V / 3Ahr Li-ion battery.
Bat Voltage = 3.59V
Load current =510mA (To mobile)
Noise Amplitude=440mV
Noise Frequency= 4.0KHz (Frequency of the signal will vary depends on Load current & battery % based on this I am able to here different hum sound ).
TO Reduce Noise :-
I tried to change TPS2500 inductor from 3.3uH to 2.2uH. --> Still noise is present.
I added 150uF bypass cap on Battery node.--> Noise ampletude reduced to half.(but still low sound noise the present)
Pls help to solve this issue.
Thanks in advance.
Regards
Raj
