Lpc1549 internal temperature sensor

[lpcware]

Content originally posted in LPCWare by MichelKuenemann on Wed Apr 01 21:34:47 MST 2015
Hello All,

I Intend to use the internal temperature sensor of the LPC1549 and I have carefuly read Chapter 31 of UM10736 (Rev 1.1).

The UM gives info about the internal connectivity of the sensor, but really  nothing about the scale of this sensor (weight of an LSB). I need also some information about its precision and its linearity.

The UM says also this :

Configure the system clock to be 50 MHz and select a CLKDIV value of 0 for a
sampling rate of 50 MHz using the ADC CTRL register.

is it really compulsory to setup precisely a 50 MHz samplig rate ? Or maybe it is a max clock rate ?



Thank you,
Regards,
Michel

[lpcware]

Content originally posted in LPCWare by MichelKuenemann on Thu Apr 02 05:47:27 MST 2015
Hello R2D2,

I did not think to check the data-sheet  !

I can find there everything I need, and even more.

Thanks a lot.

Regards
Michel

[lpcware]

Content originally posted in LPCWare by R2D2 on Thu Apr 02 05:21:30 MST 2015
Datasheet:

http://www.nxp.com/documents/data_sheet/LPC15XX.pdf

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Quote:

8.27 Temperature sensor

The temperature sensor transducer uses an intrinsic pn-junction diode reference and outputs a CTAT voltage
(Complement To Absolute Temperature). The output voltage varies inversely with device temperature with
[color=#f00]an absolute accuracy of better than ±5° C [/color]over the full temperature range  (40°C to +105°C).
The temperature sensor is only approximately linear with a slight curvature. The output voltage is measured
over different ranges of temperatures and fit with linear-least-square lines.
After power-up, the temperature sensor output must be allowed to settle to its stable value before it can be
used as an accurate ADC input. For an accurate measurement of the temperature sensor by the ADC,
the ADC must be configured in single-channel burst mode. The last value of a nine-conversion (or more)
burst provides an accurate result.

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Table 28 and Fig.43 are showing how this diode is working in detail  :O

BTW: LPCOpen Temperature sample is using 0.5 MHz  :D