TivaC ADC wrong conversion

hi, as the title says, i'm using tm4c123g with TMP136GZ temerature sensor. Now i have a wrong conversion, about double of the real temperature. I followed this topic to configure tivac:

http://e2e.ti.com/support/microcontrollers/tiva_arm/f/908/t/296196.aspx

but it's the same, i obtain a value of 50 celsius degrees.

now i tried with stellaris launchpad and it's ok

here is the cde for the adc:

void tmp36gz_setup(){


		SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);
		SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);
		ADCReferenceSet(ADC0_BASE, ADC_REF_INT);
																


		GPIOPinTypeADC(GPIO_PORTE_BASE, GPIO_PIN_5);													
		

		
		ADCSequenceDisable(ADC0_BASE, 3);																	
		ADCSequenceConfigure(ADC0_BASE, 3, ADC_TRIGGER_PROCESSOR, 0);											
		ADCSequenceStepConfigure(ADC0_BASE, 3, 0, ADC_CTL_CH8| ADC_CTL_IE |ADC_CTL_END);					
		ADCSequenceEnable(ADC0_BASE, 3);
		ADCIntClear(ADC0_BASE, 3);
}

void tmp36gz_acquisisci(uint32_t *dato){																	
	 ADCProcessorTrigger(ADC0_BASE, 3);																		
	 while (!ADCIntStatus(ADC0_BASE, 3, false));													
	 ADCSequenceDataGet(ADC0_BASE, 3, dato);																
	 ADCIntClear(ADC0_BASE, 3);																			
 }