Why does the Peakswitch PKS605 not recover from over temperature?
The PKS605 is responding to over temperature by switching off. It switches off around the specified temperature of 142°C.
After switchig off we remove the load.
When the temperature drops well below the hysteresis of 75° the PKS605 will not recover, even when cooled external below 0°C
Only after removing and reapplying the primary power it will recover. What can be done to make it work properly. Removing the primary power is not an option.
Kees, R&D, IOLAN BV, The Netherlands
Comments
Attached is the schematic with the thermal shutdown problem
Kees
Hello Kees,
First quick test is to remove R57 from your schematic. This will disable any extra functionality for Under Voltage test. I expect now your application to have no more thermal latch-up. If this is the case, you have to check the current into the EN/UV pin, must be greater than 25uA to allow restart (see http://www.powerint.com/sites/default/files/product-docs/pks_family_datasheet.pdf, page 4, Line Under-Voltage Sense Circuit). Here is the catch: when you evaluate this current, you have to consider the current coming from the AC sense circuit trough R57 plus R58 (measure the voltage on these two resistors) and the current trough R56 (measure the voltage on this resistor when you have thermal shut-down latch-up, and see what current you have there). If you are very close to the threshold, your problem could be solved by adjusting R56 or R57 plus R58.
Cheers,
PI_Crusher
Hello Kees,
I see no reason to suspect something wrong with the thermal shut-down and recovery circuit. My best bet without access to your schematic is some other condition latching the application in shut-down mode. Maybe the circuit connected to EN/UV pin?
Cheers,
PI_Crusher