Part Number:LM5166
LM5166 locks out and wont restart without power cycle. We have a temperature controller we designed for off road equipment. It controls 2 fans. about 10 % of the controls show this problem. When the temperature of the control is 160° F. the LM5166 locks out. Cooling the unit will not reset the LM5166. If we momentary remove the source power it will reset. This is true even when the temperature remains elevated. As we drive fets through a micro output to a transistor we do not believe that an over current is causing the lockup. We have replaced the brushed motors with resistors. we think this eliminates electrical noise as the trigger. We have separated the control power source from the fan / resistor power source. The lockup will occur about 8-12 hours of running at temperature of 160° F. When it locks up if we cycle the control power within seconds it will restart and run another long period. So we can restart the LM5166 at high temperatures. The current we are drawing is under 100 ma. and is dependent on the number of segments we have on on a 3 digit 7 segment display. I have attached the schematic and the layout for your review. In the field we have about 10% of the controls showing this fault. If the customer replaces with another unit he most often gets a unit that does not exhibit this problem.(Please visit the site to view this file)(Please visit the site to view this file)