Abstract: A test mode structure and method of a multi-power-source device provides for the device to remain in a test mode, during which current draw of the device may be accurately measured, even after primary power supply to the device has been greatly reduced or completely removed. Significant reduction or removal of the primary power supply while still remaining in the test mode is necessary to counter the presence of a variable current that would otherwise be normally generated by the multi-power-source device in the test mode; the presence of the variable current during the test mode, if not negated, will not permit an accurate measurement of the current draw of the multi-power-source device. Significant reduction or removal of the primary power supply to the device would typically cause the multi-power-source device to exit the test mode and switch to a secondary supply voltage supplied by the secondary power supply, thereby foiling any attempt to measure the current draw of the device.

Abstract: A power supply switching circuit employs hysteresis to ensure stable, timely, and accurate transition between a primary power source and a secondary power source of an integrated circuit. A comparison element of the circuit compares a first voltage signal derived from a primary voltage of the primary power source to a second voltage signal provided by the secondary power source in order to generate a compare output signal. A voltage divider element of the circuit, characterized as having a RC constant, is coupled to the primary power source and receives the compare signal generated by the comparison element and generates the first voltage signal. A bypass element of the circuit is coupled to the voltage divider element and is controlled by the compare signal to bypass the RC constant of the voltage divider element by immediately pulling the first voltage signal to the primary voltage when, after powering up the primary power source, the first voltage signal becomes greater than the second voltage signal.

Abstract: A power supply switching circuit ensures stable, timely, and accurate transition between a primary power source and a secondary power source of an integrated circuit. A comparison element of the circuit compares a first voltage signal derived from a primary voltage of the primary power source to a second voltage signal, also derived from the primary voltage but having a different rate of change than the first voltage signal, to generate a compare output signal. The first and second voltage signals are characterized as being equal to each other when the primary voltage is equal to a predetermined crossover point at which the integrated circuit device will be powered by the primary voltage.

Abstract: A low/zero power memory device includes a deselect mode of operation wherein row decoders, column decoders, write decoders, pre-coders, post-coders and like operational circuits of the memory device needed for wordline and column activation are disabled until such time as a memory device supply voltage exceeds a certain threshold. An included test mode circuit detects test mode activation and overrides application of the power fail deselect mode of operation of the device. This activates the wordline and column related operational circuits immediately at power up such that the device powers up with multiple wordlines and columns activated and ready for application of a stress test overvoltage.

Abstract: An integrated circuit and associated method for switching from a power supply to a battery are provided. The integrated circuit preferably includes a memory circuit responsive to an external power supply and to a battery for storing data therein and a sleep mode latching circuit connected to the memory circuit for latching the memory circuit in a reduced power sleep mode condition so as to reduce power usage of a battery and a non-sleep mode operating condition so as to allow normal operation of the memory circuit by a power supply. The integrated circuit preferably also includes a sleep mode latch locking circuit connected to the sleep mode latching circuit and the memory circuit and responsive to a power supply for locking the sleep mode latching circuit in the non-sleep mode operating condition when power supplied from the power supply falls below a predetermined threshold so that the memory circuit is inhibited from inadvertently entering the reduced power sleep mode condition.

Abstract: A circuit and method are provided for generating an initializing signal to a master enable fuse circuit on a redundant line decoder. An initialization pulse may be applied to a master enable circuit having a master enable fuse. The master enable fuse may be coupled to a switched voltage supply powered selectively by battery voltage and external Vcc. A circuit for generating the INITIAL signal determines the transition from a power down state to a powered state. A series of delay elements in a generating circuit generates a predetermined initialization pulse of around 3 ns to 5 ns. Half-latch circuits may be initialized between a first and second voltage threshold. Accordingly, the master enable circuits may be set to the proper initialization states for proper operation and minimum power consumption.

Abstract: A control circuit for terminating a memory access cycle in a memory block having at least one memory cell is disclosed. The at least one memory cell has unique process characteristics. The control circuit includes a memory block activation circuit for generating a memory block activation signal. The memory block activation circuit includes a reset circuit for terminating the memory block activation signal when activated. The control circuit also includes a memory access cycle tracking circuit, responsive to the memory block activation signal, for generating a reset signal. The memory access cycle tracking circuit includes the unique process characteristics of the at least one memory cell for tracking an operation of the at least one memory cell. The reset signal activates the reset circuit so as to terminate the memory block activation signal and terminate the memory access cycle in the memory block.