UCD3138: Questions about void configure_ton_rise(void) function in UCD3138's firmware

Hello, I am learning the firmware of UCD3138 full-bridge hard switch development board
I don't understand  void configure_ton_rise(void)

Void configure_ton_rise(void)
{
Uint32 tempo;
Tempo = pmbus_dcdc_config_translated[0].vout_cmd * pmbus_dcdc_config[0].period;
FeCtrl0Regs.DACSTEP.bit.DAC_STEP = tempo / ((Uint32)pmbus_dcdc_config[0].ton_rise * (Uint32)3885);
}

I only know that this function is used to configure the DAC's step size, but I do not know how (Uint32) 3885 is obtained?