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LDL212 in dual power system, short circuit protection.

Question asked by Alejandro Bizzotto on May 20, 2017
Latest reply on May 20, 2017 by Alejandro Bizzotto



I'm making a dual power supply (+/-12V) from +18V brick converter. To clean the DC-DC in the positive side I choose a LDL212, input is +13V from DC-DC and output is +12V.

In addition to his own over-current protection I'm using a resistor to measure current at his input, differentiator to current/voltage converter and comparator against a reference to know when the current is exceeded , the output is connected to the EN pin of the LDL212 and when the current is over the programmed limit it is switched off intermediately, also in the case of the short circuit against GND, no problems here.

But  If the other side of the over-current or short circuit is the negative rail (10ohm resistor is enough here) the regulator is burned even if the protection is working.

The datasheet says Vout should not be less than -0.3V (page 6) and seems like this is the case when the device is shorted against the negative rail, there is any way to protect the device against the negative voltage in the Vout? Or should I choose another regulator? Any suggestions?