Hello everyone,
I have question about temperature output of REF50xx voltage reference series. I know that this output is not accurate at all, datasheet says tolerance of +- 15 °C, but I noticed one thing in sheet about offset voltage at 25 °C. The thing is that this offset is listed as 575 mV in Electrical Characteristic table for all devices, but in Functional Block Diagram on page 10 is this TEMP pin driven by current source of 10 uA at 25 °C into 60 kOhm load, which gives 600 mV offset instead of 575 mV.
In fact, we are using this voltage reference a lot, so I measured few populated pieces (every piece from different batch, prototype PCBs). Lowest voltage I measured was about 585 mV = 28,8 °C, cca two degrees above PCB temp, highest voltage I measured was 609 mV = 37,9 °C, cca 11 °C above PCB temp. I did not find any piece with negative temperature error.
So my question - Is it not possible that there is a mistake with TEMP offset voltage at 25 °C? If I try to use 600 mV value to calculate temperature, all temp errors just goes down and pretty symmetrical around real temperature.
Thanks for response.
Martin Lelek
