Recently I was
asked by a company to discover why one of their products failed to operate properly in
cold temperatures. A simplified version of the circuit is shown below.
A simplified version of the circuit is shown below. Two n-channel
MOSFETs and a few resistors are wired to form a flip/flop latch circuit. Each time the
pushbutton switch is pressed, the circuit changes state and remains in that state until another activation of the switch. The circuit is used in
a 3v lithium battery coin cell powered product. The company told me that many of their
devices, when placed in a freezer to simulate operation in cold weather, would not change
state using the pushbutton switch but worked perfectly at room temperature.