Abnormal ESD failure mode with low-voltage turn-on phenomenon of LDMOS output driver

An abnormal ESD failure mode caused by a low-voltage turn-on phenomenon in an LDMOS is found on a DC-DC converter chip. Experimental investigation has shown that gate-coupling is the root cause of such low-voltage turn-on behavior. To prevent this behavior, a novel gate turn-off circuit is proposed. The solution is effective: the test chip measurements show an increase in HBM values from 1500 V to 4000 V.