# Die temperature no work well with single ended negative input equal to VRef (CY8CKIT-041-41XX board)

Level 4
Level 4

Hi,

I am testing die temperature with CY8CKIT-041-41XX board with single ended negative input equal to VRef.

No work well (Wrong values) when I change single ended negative input to VRef:

#define DIETEMP_VREF_MV_VALUE 1200

#define DIE_TEMP_GET(x) DieTemp_CountsTo_Celsius((((int32)x * ADC_DEFAULT_VREF_MV_VALUE) / DIETEMP_VREF_MV_VALUE))

Do you have a solution ?

Best regards

LuBe

1 Solution

# Re: Die temperature no work well with single ended negative input equal to VRef (CY8CKIT-041-41XX board)

Moderator
Moderator

Hi Lube,

As per the die component datasheet, for accurate measurement recommended ADC settings are :

Key parameters of ADC SAR Sequencer include:
 Channel Mode 1 – Single
 Resolution 1 – 12 bit
 Data format justification – Right
 Reference – Internal, 1.024 volts
 Sample rate – <= 100 ksps
 Samples averaged – value >16 may be used to reduce noise
 Averaging mode – Fixed Resolution
 Single ended negative input – Vss.

So the wrong results are expected in that case. These are some restrictions when die temp is measured. If you are doing some other measurement with different settings, the better way might be change between both configurations for the ADC.

Best Regards,
Vasanth

2 Replies

# Re: Die temperature no work well with single ended negative input equal to VRef (CY8CKIT-041-41XX board)

Moderator
Moderator

Hi Lube,

As per the die component datasheet, for accurate measurement recommended ADC settings are :

Key parameters of ADC SAR Sequencer include:
 Channel Mode 1 – Single
 Resolution 1 – 12 bit
 Data format justification – Right
 Reference – Internal, 1.024 volts
 Sample rate – <= 100 ksps
 Samples averaged – value >16 may be used to reduce noise
 Averaging mode – Fixed Resolution
 Single ended negative input – Vss.

So the wrong results are expected in that case. These are some restrictions when die temp is measured. If you are doing some other measurement with different settings, the better way might be change between both configurations for the ADC.

Best Regards,
Vasanth

# Re: Die temperature no work well with single ended negative input equal to VRef (CY8CKIT-041-41XX board)

Level 4
Level 4

Hi Vasanth,

the MCU of board has only 1V2 and the die temperature works well but when I select vref as single ended negative input for having more range 0-1V2*2, the value is wrong but stable.

For example, with 1V2 ref the temperature is about 29°C, but with Vref as single ended negative input the temperature goes to 374°C.

I think there is a relation between the configuration withj Vref as single ended negative input the temperature.

Best regards

Luca Bernabei