Power up detection circuits

摘要

A power up detection circuit is provided which includes a power supply terminal, an output terminal, an impedance device coupling the output terminal to the power supply terminal and a latch including a first inverter having a first device connected between the output terminal and a point of reference potential and a second device connected between the output terminal and the power supply terminal, the devices are designed so that subthreshold current passing through the first device is greater than the effective subthreshold current passing through the impedance device and the second device, and a second inverter including third and fourth devices which are designed so that a smaller subthreshold current passes through the third device than the subthreshold current passing through the fourth device. The power up circuit may further include a capacitor connected between the power supply terminal and gate electrodes of the first and second devices.