A semiconductor flip flop capable of operating before, during and after an ionizing radiation environment. The radiation hardening is achieved by use of a capacitive memory in the cross coupled feedback loop of the flip flop circuit to drive the flip flop back to its pre-irradiation state.

Radiation hardened flip flop

A capacitor in parallel with a CMOS memory is used, in the event of a power outage, to apply a sufficient temporary voltage to the memory to maintain the stored data. Data storage retention time is maximized by a resistor, connected between the capacitor and the memory, having a resistance R approximately given by R = 0.4 (V.sub.i - V.sub.f)/I.sub.f (1) where V i is the initial voltage on the capacitor, V f is the minimum voltage for maintaining the data and I f is the capacitor discharge current at voltage V f .

Voltage maintenance apparatus

A sensor with a dynamic latch comprising having a sensor coupled to a gain amplifier, a delay circuit connected to the gain amplifier and a summing circuit coupled through first and second nodes to the gain amplifier The sensor with a dynamic latch further comprises an output stage coupled to a comparator circuit and the summing circuit and to third and fourth nodes and first and second energy storing devices coupled to the comparator circuit

Sensor with a dynamic latch

Apparatus for retaining the data held in a directional counter in the event of the voltage level supplied to the counter falling below a predetermined level comprises a directional counter means for comparing the level of voltage supplied to the directional counter with a predetermined voltage level, data storing means responsive to the comparator means for storing the output signal of the directional counter when the voltage falls below the predetermined voltage and for loading the stored output signal into the directional counter when the voltage level subsequently rises above the predetermined level.

Data retention apparatus

A user-operable power-up mode switch included within an electronic air conditioning mode control circuit of the type including momentarily-actuated user mode selection switches and a volatile mode selection memory. In the event of power interruption, the mode selection memory "forgets" the last selected mode after a relatively short time when power supply filter capacitors have discharged. The power-up mode switch allows user selection of the particular mode in which operation resumes upon power restoration, but the user power up mode selections do not include all the operational modes selectable by the momentarily-actuated user mode selection switches. Thus operation continues in a mode at least appropriate for the season.

Air conditioning control system with user power up mode selection

There is provided a temporary memory restore circuit for actuating a bistable multivibrator to its last stable state prior to removal of power, when power is returned to the circuit. The memory restore circuit includes a storage capacitor, which is connected across the output of the bistable multivibrator. The capacitor monitors the operation of the multivibrator and is charged in accordance with the last stable state of the multivibrator. Connected in series with the storage capacitor is a normally open circuit means for connecting the capacitor across the output circuit of the bistable multivibrator when power is applied to the circuit, and for disconnecting the capacitor from the circuit when power is removed.

Peter G Bartlett

Papers

Temporary memory restore circuit for multivibrator