The typical single conversion times for the CS0 module on the C8052F97x, C8052F97x, and the EFM8SB1, as listed in the datasheet for 12-bit, 13-bit, 14-bit, and 16-bit modes are 25, 27, 29, and 33 us, respectively. How do these typical conversion times change depending on the clock source and frequency of SYSCLK (i.e. LPOSC0, HFOSC0, EXTCLK, RTCOSC, LFOSC0)?
The CS0 module present on the C8051F97x, C8051F99x, and EFM8SB1 devices has its own dedicated oscillator which is active whenever the module is enabled. Thus, the choice of oscillator source for SYSCLK will not affect the conversion times specified in the datasheet (which are for the default configuration).
Other factors that might affect the conversion time (or the time between conversion complete interrupts) are the accumulator setting (CS0ACU in CS0CF) and the conversion rate (CS0CR in CS0MD2 - though this is covered in the default electrical specifications).