CC1310: CC1310定时器时间不对

void Timer0_Callback(void)
{
    TimerIntClear(GPT0_BASE, TIMER_TIMA_TIMEOUT);//清空中断
    GPIO_toggle(Board_GPIO_LED0);
}

void Timer0_Init(void)
{
    // Power on the TIMER0 peripheral
    PRCMPeripheralRunEnable(PRCM_PERIPH_TIMER0);

    TimerDisable(GPT0_BASE, TIMER_A);
    TimerConfigure(GPT0_BASE,  TIMER_CFG_SPLIT_PAIR |TIMER_CFG_A_PERIODIC_UP);
    TimerLoadSet(GPT0_BASE, TIMER_A, 200);
    TimerPrescaleSet(GPT0_BASE, TIMER_A, 48-1);//实际分频值加1
    //TimerIntervalLoadMode(GPT0_BASE, TIMER_A, TIMER_INTERVALLOAD_NEXTCYCLE);//更新模式：在下个时钟周期

    TimerIntRegister(GPT0_BASE, TIMER_A, Timer0_Callback);
    TimerIntEnable(GPT0_BASE, TIMER_TIMA_TIMEOUT);
    TimerIntClear(GPT0_BASE, TIMER_TIMA_TIMEOUT);//清空中断
    TimerEnable(GPT0_BASE, TIMER_A);
}

请问这段代码定时器时间视乎不起作用，一直是63.9ms，改LOAD值定时时间也不变，不知是哪的问题。