Regarding the buck circuit constructed by LT1076 and LT8640, LT8640 is slightly inferior in terms of noise,
The usage conditions of the two chips are Vin=24V, Vout=9.7V, Iout=1.5A, and the load is a light bulb, with relatively stable load conditions.
For the noise improvement of LT8640, the following adjustments have been made:
1. Add a Electrolytic capacitor to the output capacitor==>Not improved
2. Increase or decrease the output voltage="without improvement
3. Adjust the chopping frequency to 200kHz and replace the capacitor with 47uH (XAL7070-473ME)=="The noise situation has improved, but it is still worse than LT1076
● Noise testing environment:
Connect the buck circuit power boards constructed by LT1076 and LT8640 respectively into the system for an average peak to peak noise measurement of 1 hour.
(The only variable in the testing environment is this power board)
● Noise test results:
The noise of LT1076 is 5-6, and the noise of LT8640 is 8-9
Current conjecture:
1. Noise is related to inductance, does LT8640 not match the current inductance? What is the matching sensitivity value?
2. Does the DC resistance parameter of the inductance have an impact on noise?
Also:
The circuits of the two types of ICs are as follows, please refer to
LT1076:
LT8640S:
