Hi everyone,
I designed a PCB which control multiple proximity sensor VCNL4040 with ESP32 , the image is schematic. I am using multiplexer I2C tca9548a to connect multiple i2c (sensors) and these sensors power at 3.3V. Could you guys check schematic for me? I need some feedback and improvement from you guys. Thank you very much
Overall it looks OK. The schematic is fuzzy on my monitor and I cannot read most of the labeling. The BA338 has a critical capacitance requirement with a narrow ESR rating. The following is from the data sheet:
The capacitance may vary greatly with temperature changes, thus making it impossible to completely prevent oscillation. Therefore, use a tantalum aluminum electrolytic capacitor with a low ESR (Equivalent Serial Resistance). The output will oscillate if the ESR is too high or too low, so refer to the ESR characteristics in Fig.22 and operate the IC within the stable region. Use a capacitor within a capacitance between 22μF and 1,000μF. Below figure, it is ESR-to-Io stability Area characteristics, measured by 22μＦ-ceramic-capacitor and resistor connected in series. This characteristic is not equal value perfectly to 22μＦ-aluminum electrolytic capacitor in order to measurement method.
Note, however, that the stable range suggested in the figure depends on the IC and the resistance load involved, and can
vary with the board’s wiring impedance, input impedance, and/or load impedance. Therefore, be certain to ascertain the final status of these items for actual use. Keep capacitor capacitance within a range of 22μF to 1000μF. It is also recommended that a 0.33μF bypass capacitor be
connected as close to the input pin-GND as location possible. However, in situations such as rapid fluctuation of the input voltage or the load, please check the operation in real application to determine proper capacitance.
I also suggest bypassing each of the VCNL4040 devices.
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.