JAJSSD2A October 2023 – December 2023 BQ25638
PRODUCTION DATA
デバイスごとのパッケージ図は、PDF版データシートをご参照ください。
Normally, the device switches with a fixed frequency. The charger also supports a frequency dithering function to improve EMI performance and help pass IEC-CISPR 22 specification. This function is disabled by default with setting EN_DITHER=00b. It can be enabled by setting EN_DITHER=01/10/11b, the switching frequency is not fixed when dithering is enabled, it varies within determined range by EN_DITHER setting, 01/10/11b is corresponding to ±2%/4%/6% switching frequency. The larger dithering range is selected, the smaller EMI noise peak will be, but at same time slightly larger VBUS/VSYS capacitor voltage ripple is generated. Therefore the dithering frequency range selection is a trade-off between EMI noise peak and VSYS/VBUS voltage ripple, recommend to choose the lowest dithering range which can pass IEC-CISPR 22 specification. The patented dithering pattern can improve EMI performance from switching frequency and up to 30MHz high frequency range which covers the entire conductive EMI noise range.