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TSC2046: Temperature measurement

Part Number: TSC2046


We see sbas265g page 15 table3, and temperature measurement is available

in case Single-ended only.


Customer had chosen TSC2046 for their portable equipment 2018 model ( Mass Production is soon),

but due to their MCU software error, customer has case#2 occasionally.

===
Case#1
Table3
10000100b : A2~A0=0 SER/DFR=1 ==> definded in Table 1 : "+IN TEMP0 measurement"

Case#2
Table3
10000000b : A2~A0=0 SER/SFR=0 ==> not defined in data sheet. So, it it not applicable

===


As per customer, Case#1 has always no problem ( resolution 1.6 deg-C) , but in Case#2,

resolution is 3.2 deg-C.

(see below ~~~)


Customer had fixed by changing their software correctly, but customer need your comment.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Case#2

Measure at Ta=22deg-C


deg-C times
12.8 1
16 1
19.1 7
22.2 10

Total N-19 times

~~~~~~~~~~~~~
Case1

Ta=26 deg-C

deg-C times
19.1 2
20.7 11
22.2 6
23.8 6
25.4 241
27 284
28.5 9
30.1 4
31.7 6
41.1 1

Result:

resolution is 1.6 deg-C ( its correct)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


< Question >

As per customer's data, it looks like just LSB of data is lost, when they set wrong setting

as case2( differential).


However, would you please give your comment or idea about the reason?

Customer willing to use TSC2046 in correct way, but please have your opinion.

Best Regards

  • Hi Kanji,

    Take a look at Figure 2 in the TSC2046 datasheet, note the last two switches (dashed line from Logic block under SER/DFR). The SER/DFR input is shown low, which means you are taking a differential measurement between +/- inputs. When SER/DFR is high, those two switches flip down and you are taking -REF to GND for a single ended measurement. For the TEMP measurement [A2..A0] = 0, you need that REF- grounded. Fixing the software is the correct thing to do.
  • Dear Hendrik-san

    Thank you for your answer.

    I understood that resolution may becomes 1 of 2 ( LSB lost ) due to differential measurement.

    Thank you