Cherry Semiconductor Corporation

Frank J Kolanko

Jay D Moser, Sr

Donald R Laybourn

Robert M Lanoue

A programmable oscillator comprising a switching circuit, a first driver circuit, and a second driver circuit, the oscillator being programmable to switch at a first switching frequency or a second switching frequency by utilizing only one external capacitor and two external resistors. Only one driver circuit is active at a time to charge and discharge the capacitor at one of the switching frequencies. The driver circuits are made active or inactive by a control circuit.

Programmable oscillator using one capacitor

An output driver for providing a gate voltage to an external positive-channel field-effect transistor (PFET) device. A capacitor accumulates charge which, upon switching by an input switching signal, is applied, in addition to the supply voltage, to the base of a drive circuit NPN transistor to rapidly pull the PFET gate voltage, derived at the emitter of the drive circuit NPN transistor, up to the supply voltage. An active voltage limiter, coupled in parallel with the drive circuit, limits excursion of the gate voltage with respect to the supply voltage.

Output driver for high-speed device

A low voltage indicator circuit including a self-biased driver circuit. A voltage at the output terminal is used to create a bias voltage to operate the driver when less than a threshold voltage is present on at least one voltage supply line. A transistor for supplying base drive current to the driver has a base coupled to the at least one voltage supply line in one embodiment and to the bias circuit in other embodiments. The transistor in the one embodiment provides base drive current to the driver when voltage on the at least one voltage supply line is less than the voltage on the output terminal by at least a predetermined amount. In other embodiments, the bias circuit may include a FET or resistor coupled between the output terminal and the base of a bias circuit transistor. The bias circuit transistor has a terminal connected to a bias resistor for providing current through the bias resistor when the bias circuit transistor is turned on. A switch connected to the base of the bias circuit transistor selectively directs the current from the FET or resistor to or away from the base of the bias circuit transistor. Current is directed to the base of the bias circuit transistor when less than a threshold voltage is present on the at least one voltage supply line. This causes current to flow through the bias resistor developing a bias voltage thereacross.

Low voltage indicator with a self-biased driver circuit

A method for powering up an integrated circuit and circuit for implementing the method. A first charging current is used to slowly charge a capacitor used in the integrated circuit upon connecting the power. A power-up signal is provided to initialize digital circuitry until the first charging current raises the voltage of the capacitor above a threshold value. Once a capacitor is charged to another predetermined threshold, a second charging current is activated. The two charging currents are thereafter used as the total charging current on the capacitor. If the capacitor is grounded, the initial power-up scheme is re-initiated.

Power up and oscillator circuit using a single capacitor

A positive temperature coefficient current source having reduced reference current requirements. The output transistors are each buffered by another transistor in a Darlington pair configuration. The reference current required for the circuit is reduced while maintaining a positive temperature coefficient for the current source.

Growing community of inventors

Greenville, RI, United States of America

Frank J Kolanko