Harris Corporation

Other

Thomas R Deshazo, Jr

Raymond L Giordano

Donald R Preslar

A method and circuit for preventing forward bias of a collector-substrate diode in an integrated circuit with a bipolar transistor where a load driven by the transistor may be offset from a reference voltage, such as circuit ground, by a varying voltage offset. The difference between the bipolar transistor collector voltage and the reference voltage is sensed, and the bipolar transistor base current is varied responsive to the sensed difference so that the base current is zero when the collector voltage is equal to the reference voltage, whereby the collector current will be less than .beta. times the base current when the emitter voltage is less than the reference voltage and the diode will not become forward biased.

Method and circuit for preventing forward bias of a parasitic diode in

A method and apparatus for stopping the operation of a failed device and preventing that device from being turned back on is shown, using two thresholds, a first failure threshold is shown when the device may be turned off or prevented from further operation. A second safe operation threshold is shown, different from the first threshold and within the safe operation range of the device. As the temperature rises, this transistor is driven further to conduction diverting base current from a second transistor and driving it further into nonconduction. The collector current from the second transistor is diverted to a resistor providing additional bias to the temperature sensitive transistor and driving it to a new bias. This bias establishes the second threshold. According to the inventive principles, the device is prevented from being turned back on until the safe operating threshold is reached. Further, a second condition requiring the reset signal for the device to be cycled through one complete cycle from off to on is shown. In the preferred embodiment, a temperature sensitive transistor is shown having a negative temperature coefficient.

Apparatus for controlling the reset of a bus connected transceiver

An IC is constructed with deep layers preventing current flow due to parasitic transistors formed within the IC. Reverse current in case of voltage source polarity reversal is prevented by means of the reverse bias diodes formed by the addition of a P+ ring, and N+ well, for the embodiment disclosed.

Reverse current flow prevention in a diffused resistor

A transistor built on a substrate employs two collectors, an output collector and a secondary collector. The purpose of the secondary collector is to collect minority carriers at saturation and feed these minority carriers back to the input reference of a current mirror. This saturation current causes a decrease in the current through the input reference transistor and decreases the current in the output of the current mirror responsively, driving it away from saturation.

Current mirror with saturation limiting

A current rise in fall time limited voltage follow is shown having a voltage driver providing a voltage signal into a current driver. The output of the current driver is a load varying in resistance, for example, as the number or combination of devices connected to the load vary. The maximum current into the load and the maximum rise time of the current into the load is limited at the output of the current driver to a maximum by the input impedance of the current driver. The rise time and the current into the load may increase until the resistance of the load is substantially that of the current driver input resistance reduced by a factor of N. The factor N is the maximum current capability of the output of the current driver related to the current driver input current generated by the voltage signal from the voltage driver. The current into the load and the maximum rise time of the load will increase until the load resistance R is less than the input impedance of the current driver divided by the current multiple N at the output of the current driver related to the current at the input of the current driver.

Current rise and fall time limited voltage follower

A normally non-conducting control device whose turn-on threshold decreases with increasing temperature is supplied with a control voltage which increases with temperature for causing a more rapid increase in the conduction of the control device when a predetermined temperature is exceeded.

Integrated circuit thermal sensor

First and second resistors are connected in series with a Zener diode between first and second points of operating potential. The base-to-emitter of an NPN transistor is connected across the first resistor to sense the current through the series path. The collector-to-emitter of a PNP transistor is connected across the second transistor, whereby when the PNP transistor is turned-on hard and into saturation, the voltage drop across the second transistor decreases. The collector of the NPN transistor is connected to the base of the PNP transistor, whereby when an overvoltage condition exists and the Zener diode breaks down, the two transistors are driven regeneratively and form a latch and the operating point of the circuit is shifted.

Growing community of inventors

Frenchtown, NJ, United States of America

Thomas R Deshazo, Jr