Xilinx, Inc.

Farshid Shokouhi

Michael G Ahrens

Arthur H Khu

Ben Y Sheen

Qi Lin

Conrad A Theron

Hassan K Bazargan

Pushpasheel Tawade

Structure and method for updating a system that includes a memory and a programmable logic device (PLD) retains a default PLD configuration in the memory while a new configuration is being stored in the memory, and thus protect the system from failure in case an interruption occurs while the new configuration is being stored. If a power failure interrupts the storing process, the default PLD configuration is still in the memory and can be re-loaded into the PLD and used when the system is re-started to make a further attempt at storing the new configuration. Methods are also disclosed for storing in the memory a configuration for a new PLD before the original PLD is replaced so that system hardware can be updated with minimum effort and disruption, and for dividing a directory structure into protected and unprotected regions.

Fail-safe method of updating a multiple FPGA configuration data storage system

According to the invention, a JTAG-compliant chip having a controller that receives data provided on the TDI input pin and forms parallel address and data instructions and passes the data through IO pins to the non-JTAG chip is able to verify whether the data was correctly received by the non-JTAG chip by reading back the data and comparing to the original data. A status bit or bits are shifted out on a TDO pin and used to determine what data will be shifted in next.

Structure and method for verifying data in a non-JTAG device from a JTAG device with microcontroller

According to the invention, a JTAG-compliant chip is further provided with a controller that receives data provided on the TDI input pin, forms parallel address and data instructions and passes the data through IO pins to the non-JTAG chip without requiring the data to go through the boundary scan register chain of the JTAG-compliant chip. This controller is used to program, erase, and read the other chip. For a non-JTAG flash memory device, the controller in the JTAG-compliant chip generates the necessary programming signal sequences, and applies them to the non-JTAG chip without going through the JTAG boundary scan circuitry.

Structure and method for writing from a JTAG device with microcontroller to a non-JTAG device

A trigger circuit for an In-System Programmable (ISP) memory device that operates with a JTAG interface. The trigger circuit receives instruction signals from the JTAG control circuitry, and limits the duration of these instruction signals to avoid erroneously repeating ISP programming operations. The trigger circuit includes a first logic circuit, a delay circuit, and a second logic circuit. The first logic circuit generates a logic high output when both the JTAG RUN-TEST and a program instruction signal are simultaneously asserted, and causes the second logic circuit to toggle the limited duration instruction signal into a logic high state. The delay circuit also detects the simultaneous assertion of the JTAG RUN-TEST and a program instruction signal, and generates a cancellation signal after a predetermined number of clock cycles. The cancellation signal causes the second logic circuit to toggle the limited duration instruction signal into a logic low state.

In-system programmable flash memory device with trigger circuit for generating limited duration program instruction

The present invention provides a tunable circuit for quickly optimizing an electrical field generated by the F-N tunneling operation. To optimize this electrical field, the charging of a positive charge pump is begun after the charging of a negative charge pump. The tunable circuit of the present invention provides a means to detect the optimal negative voltage at which pumping of the positive voltage should begin. The tunable circuit includes a resistor chain coupled between a first reference voltage and a negative voltage from the negative charge pump. When charging of the negative charge pump begins, a comparator compares the voltage at a node within the resistor chain to a second reference voltage. In accordance with the present invention, the node voltage within the resistor chain is equal to the second reference voltage when the negative voltage is equal to the voltage to be detected. Thus, the comparator generates a trigger signal when the voltage at the node decreases to the second reference voltage. This output signal triggers the pumping of the positive charge pump. By changing the resistance within the resistor chain, the positive charge pumping may be initiated at varying negative voltages. In the present invention, additional resistance is added to or removed from the resistor chain via metal options or switches.

Tunable circuit for detection of negative voltages

A one-shot system for loading a bitline shift register with a typical test pattern is described. Each bitline latch within the bitline shift register is augmented with a one-shot circuit that may pull-up or pull-down the value stored in the bitline latch. The choice of a particular memory test pattern dictates the control of the one-shot circuit.

Automatic bitline-latch loading for flash prom test

The present invention provides a tunable circuit for quickly optimizing an electrical field generated by the F-N tunneling operation. To optimize this electrical field, the charging of the positive charge pump is begun after the charging of the negative charge pump. The tunable circuit of the present invention provides a means to detect the optimal negative voltage at which pumping of the positive voltage should begin. The tunable circuit includes a resistor chain coupled between a first reference voltage and a negative voltage from a negative charge pump. When charging of the negative charge pump begins, a comparator compares the voltage at a node within the resistor chain to a second reference voltage. In accordance with the present invention, the node voltage within the resistor chain is equal to the second reference voltage when the negative voltage is equal to the voltage to be detected. Thus, the comparator generates a trigger signal when the voltage at the node decreases to the second reference voltage. This output signal triggers the pumping of the positive charge pump. By changing the resistance within the resistor chain, the positive charge pumping may be initiated at varying negative voltages. In the present invention, additional resistance is added to or removed from the resistor chain via metal options or switches.

A high voltage level-shifter that facilitates the conversion of typical positive logic input signal voltages to non-positive (i.e., at or below ground) output signal voltages. The high voltage level-shifter is separated into two voltage shifting circuits that are connected in parallel between a circuit input terminal and a circuit output terminal. The first voltage shifting circuit includes an isolation switch (e.g., a pass transistor) connected between a positive voltage source and a positive supply rail of an output driver. The negative supply rail of the output driver is connected to one of the non-positive voltage sources. An output control circuit controls the isolation switch to couple the positive voltage source to the positive supply rail of the output driver only when the negative voltage source is driven onto the circuit output terminal (i.e., in response to a logic &ldquo;1&rdquo; input signal).

High voltage level-shifter with tri-state output driver

In a charge pump system, the frequency of an oscillator is based on the output signals from a plurality of differential amplifiers. Each differential amplifier receives a different reference voltage as well as a common input voltage derived from the pumped voltage. A predetermined logic signal output by the differential amplifiers modifies, i.e. reduces, an original frequency of the oscillator. In this manner, the charge pump system quickly compensates for any overshoot in the pumped voltage in a manner directly correlated to the magnitude of the pumped voltage. If no differential amplifiers output the predetermined logic signal, then the oscillator generates the original frequency. In this manner, the charge pump system also compensates for any undershoot in the pumped voltage by providing the fastest frequency.

Frequency controlled system for positive voltage regulation

A floating gate memory device that includes a switching circuit for selectively transferring two or more negative voltages to a common node (e.g., to the negative pole of a driver circuit). The switching circuit includes two switches respectively connected between the two negative voltages and the common node. Each of the switches includes series-connected triple-well NMOS transistors that provide a dual-isolation structure between the common node the negative voltage sources. An optional triple P-well resistor is provided between the series-connected triple-well NMOS transistors in each of the switches that includes a deep N-well region biased by a system voltage source (e.g., VCC) to reverse bias the central P-well region.

Switching circuit for transference of multiple negative voltages

A floating gate memory device that includes a column latch circuit that is isolated from a series of bitlines by PMOS pass transistors controlled by a bitline latch switch circuit. The bitline latch switch circuit selectively applies either &plus;5 V or &minus;2 V signals to the gate terminals of the PMOS pass transistors, thereby allowing the PMOS pass transistors to selectively pass 0 (zero) Volts during, for example, program operations. A &minus;2 V charge pump is activated to generate the &minus;2 V signal during operations requiring 0 Volt bitline voltages, and is turned off during all other operations.

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San Jose, CA, United States of America

Farshid Shokouhi