Hi
We are using TPS61193 part in one of design for Gauge illumination and TFT backlight section.
Hearing Audible noise in below ranges:
Gauge illumination inductor from VIN - 13.2V to 13.6V (Non-Shielded type inductor)
TFT illumination backlight inductor from VIN - 16.5V to 16.8V, (Using Shielded type Inductor)
Design operating range is Vin = 6V to 18V.
Findings:
1. Below is schematic image, used 1 x 47uF(electrolyte Cap) & 2 x 10uF(Ceramic Cap) and I changed the ceramic cap (C911 & C912) to 22uF and still hear audible noise.
2. I removed the 2x10uF(Ceramic cap) and audible noise is completely reduced, But TPS61193-Q1 datasheet recommend to use Ceramic cap in Note A and whereas in Note B recommend to use physical size ceramic cap should be minimized.
Query:
1. What will impact if i remove the ceramic cap ?. Since product in final stage and not in place to change the inductor to shielded type from Non-shielded type
2. Without removing capacitor, what would be TI recommendation to isolate the audible noise.
Note A:
Note B:
Thanks and Regards
Balakrishnan