We have an application where it has been difficult to prevent emissions from BQ24193RGET charger from "de-sensitizing" a radio on the same tiny circuit board. The "VBUS" input voltage is nominally 12V. Among many actions to control the RF interference, including shielding can, careful routing of PMID capacitors wiring (to PMID & PGND) and general grounding optimization, we have also considered reduction of switching speed by inserting a small resistor in series with the bootstrap capacitor connected to BTST. See the applied schematics snapshot, where that resistor is R2038 (in this case 0R). In our tests having 10 ohms on BTST reduced emissions significantly. At the same time we couldn't see any significant negative effects on the tested sample, except an acceptable, and nearly not measureable, decrease of efficiency. This idea was btw. picked up from TI:s document slyt465.pdf (Controlling switch-node ringingin synchronous buck converters).
However, the data sheet doesn't give any guideline regarding such a resistor on BTST. The question is: Is it recommendable to use such a resistor in BTST circuit? If yes, how to dimension the additional resistor so that we can guarantee that the product works OK over temperature range and IC'sfrom cghip-to-chip parameter variations?
