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some questions about adn8830

Question asked by Xinyi on Aug 24, 2016
Latest reply on Aug 30, 2016 by Xinyi
HERE, there are several  questions when i use ADN8830 as the TEC controller.
 1. In the high temperature test(60℃), when the pin 15(VLIM) was connected to the GND, the current of the TEC controller was smoothly increased which is like the linear curve. BUT THEN, the current was the sharply increased from 700mA to 1.7A in 30 second. if a voltage applied to the VLIM input to the ADN8830, the sharply increasing will not happen again. WHY?
(The max of TEC current is 1.9A,The max of TEC voltage is 6V, we use FDW2521 as the MOSFET)
2. we use  the multimeter to measure the current and voltage of Q3(P-MOSFET) in the AN8830 datasheet Fig.1, Page7.
Notice that the voltage of Udg is reversed to the positive number at the beginning  of cooling period.
i just wanna know that these two phenomenons are OK or WRONG 'caused by some reasons????