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updated over-voltage answer based on analysis of the latching circuit
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bmow
bmow
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Your SN74LVC00 chip is consistently burning and smoking when yourlatching circuit design will briefly apply up to 10V to U1 pin 1, when the switch is powered on. That's clear evidencereleased, due to the action of highC1. Since the chip's absolute maximum input voltage fromis 6.5V, this will damage or destroy the batteries somehow finding its way to that chip, as evidenced by the burning and destroying itsmoking you observed. Probe all the pins with

The example latching circuit you referenced calls for a multimeterCMOS logic gate such as CD4011, which has a 3V to find18V supply range, and can tolerate a 10V pulse. But your circuit uses a 74LVC00, which one is above 5Vcan't.

Your SN74LVC00 chip is consistently burning and smoking when your circuit is powered on. That's clear evidence of high voltage from the batteries somehow finding its way to that chip, and destroying it. Probe all the pins with a multimeter to find which one is above 5V.

Your latching circuit design will briefly apply up to 10V to U1 pin 1, when the switch is released, due to the action of C1. Since the chip's absolute maximum input voltage is 6.5V, this will damage or destroy the chip, as evidenced by the burning and smoking you observed.

The example latching circuit you referenced calls for a CMOS logic gate such as CD4011, which has a 3V to 18V supply range, and can tolerate a 10V pulse. But your circuit uses a 74LVC00, which can't.

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bmow
bmow
  • 308
  • 2
  • 9

Your SN74LVC00 chip is consistently burning and smoking when your circuit is powered on. That's clear evidence of high voltage from the batteries somehow finding its way to that chip, and destroying it. Probe all the pins with a multimeter to find which one is above 5V.