摘要:
An array source signal discharge controller device (10) includes a pulse converter circuit (12) that receives an erase pulse signal (ERPULSE). The pulse converter circuit (12) converts the erase pulse signal (ERPULSE) into a pulse control signal (ERPCL) that is subsequently translated into a higher voltage level bias signal (ECL.sub.--). The higher voltage level bias signal (ECL.sub.--) drives array source signal generator circuits (16) that produce array source signals (AS) to erase particular array subsections of memory as determined by a selection circuit (17). The array source signal generator circuits (16) also generate array source command signals (ASCOM.sub.--) to indicate a discharging status of all array source signals (AS). An erase completion detector circuit (18) monitors the array source command signals (ASCOM.sub.--) and generates an array source detect signal (ASDET) to indicate completion of array source signal (AS) discharging. The pulse converter circuit (12) receives the array source detect signal (ASDET) and generates an erase completion signal (ERCTR) and a pulldown control signal ERCTR.sub.-- to control final discharge of the array source signals (AS) and indicate that normal memory access may resume. The pulse converter circuit (12) also generates a pulldown signal (ERD.sub.--) that controls discharge of the array source signals (AS) by preventing current surges from appearing on the array source signals (AS) during discharge.
摘要:
The power-on reset circuit of this invention includes a current-sensing circuit, a pulse-stretching circuit, and a voltage-reference circuit. The voltage-reference circuit consists, for example, of one N-Channel and one P-Channel MOS transistor. The circuit of this invention uses a static voltage reference comprised of CMOS transistors to detect the power-up condition. The circuit of this invention improves detection of a transient power-supply voltage Vcc loss and detects that power-supply voltage transient on both rising and falling edges.
摘要:
The column-line short detection circuit of this invention includes a special test circuit that turns off wordlines (15), a N-channel transistor (23) for each column line (18), a decoder (19a) that uses only the least significant column address (20d) for input to the test circuit, and a sensor (SA) to detect current between shorted column lines (18). Because the column-line short detection circuit of this invention uses only the least significant address as input for column decoder (19a), it requires a very small number of transistors.
摘要:
In a multi-sector nonvolatile memory array in which each memory cell has a drain coupled to a bitline, each memory cell of each sector has a source coupled to a common array-source line, each memory cell in a row of the first sector has a control gate coupled to a wordline and each memory cell of a row in another sector has a control gate coupled to that wordline, a method for programming a memory cell in one sector of said method includes connecting at least the second common array-source line to each bitline coupled to drains of columns of memory cells in the another sector, then biasing at a positive voltage both the common array-source line and the bitlines coupled to drains of memory cells in columns of the another sector, and then applying a programming voltage to the selected wordline coupled to the control gate of the selected cell in the first sector. An erasing method includes connecting the wordlines to a reference voltage, connecting at least one deselected common array-source line to each bitline coupled to drains of columns of memory cells in the deselected sector, then biasing at a positive voltage both the deselected common array-source line and said bitlines coupled to drains of memory cells in columns of the deselected sector, and then applying a positive erasing voltage to said common array-source line of the selected sector.
摘要:
A supply-voltage detecting stage (11) that supplies first and second reference currents (I.sub.REFP and I.sub.REFN) which vary with the supply voltage (V.sub.cc) and are coupled by first and second gain stages (12A and 12B), respectively, to first and second temperature-detecting stages (13A and 13B), respectively. First and second temperature-detecting stages (13A and 13B) increase the coupled reference currents (I.sub.REFP and I.sub.REFN), respectively, to compensate for temperature increase through use temperature-sensitive, long-channel transistors (M34-M37 and M42-M45), supplying temperature and supply-voltage compensated output bias voltages at output terminals (MIRN and MIRP).
摘要:
The power-on-reset test circuit of this invention includes two imbalanced latches to detect the occurrence of a transient power-on-reset signal. The occurrence of a transient power-on-reset signal is latched for later verification during circuit testing. Both latches are designed to default to a low voltage output (Vss) on initial power-up. One of the latches is set by the power-on-reset signal to a high-voltage output (Vcc) state. The other latch is set by a reference-potential input to a low-voltage output state. If the set latch has a high-voltage output and the other latch has a low-voltage output, then the power-on-reset circuitry is functioning properly.
摘要:
The CMOS high-voltage sensor circuit has a voltage reference including, for example, of four N-channel MOS transistors; one pass-gate P-channel transistor; one current-mirror P-channel MOS transistor; and a conventional high-voltage sensor including, for example, of two P-channel MOS transistors and one N-channel MOS transistor. The sensor circuit of this invention generates a high-voltage signal at the output if the input voltage is greater than both the reference voltage plus two P-channel threshold voltages and the supply voltage Vcc plus two P-channel threshold voltages. The power-up or power-down sequence may be in any order without adversely affecting the operation of the circuit of this invention.
摘要:
The method of this invention prevents transient currents at high-frequency disable cycles and disables DC current paths after a minimum delay time, thereby reducing power dissipation. This invention includes a delay circuit functioning to prevent disablement of DC paths where chip-disable times occur at intervals below a minimum duration. The result is a decrease in the number of undesired voltage drops on internal power buses due to transient currents. The method detects external chip-disable pulses that occur before a minimum time duration, then prevents those pulses from powering down internal direct-current paths. At the same time, the output driver high impedance functionality of the chip-disable signal is preserved.
摘要:
A procedure for erasing a Flash EPROM array (AR) includes applying a series of erase pulses to all of the subarrays (S1, S2, etc.) of a Flash EPROM array (AR) simultaneously. Between each erase pulse, the memory cells (10) of each sub array (S1, S2, etc.) are simultaneously checked one row at a time and one column position at a time, to see whether or not any cell (10) is over-erased. If, at any time during the procedure a cell (10) is found to be over-erased, the over-erased condition is corrected and the erase procedure continues, but with erase pulses applied only to those subarrays (S1, S2, etc.) having non-erased memory cells (10) as in prior-art subarray erase procedures. Under almost all circumstances, the procedure of this invention decreases over-all erase time.
摘要:
A wordline-decode system of a nonvolatile memory array is split into three smaller decoding subsystems (a Read-Mode Decode Subsystem, a Program/Erase-Mode Decode Subsystem and a Segment-Select Decoder Subsystem). The segmented array has small bitline capacitance and requires few input connections to each decoding subsystem. The Read-Mode Decoder circuitry and the Program/Erase-Mode Decoder circuitry are separated, allowing the Read-Mode Decoder circuitry to be desired for high speed access and allowing the Program/Erase-Mode Decoder circuitry to be desired for high voltage operation. Buried-bitline segment-select transistors reduce the area required for those transistors. Erasing may be performed after first checking each row of a segment to determine the present of any over-erased cells. Programming may be performed by allowing the common source-column lines of the selected segment to float and by placing preselected voltages on the appropriate wordline and drain-column line.