Microcontroller memory cell current reading method
AssigneeSGS-Thomson Microelectronics S.A.
InventorSaverio Pezzini
Life of this patent
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Abstract
A method is provided for directly reading the current of cells of a memory forming part of a microcontroller by performing a write operation of the cells and using the existing cell programming logic. For this purpose, the programming voltage supply line is supplied with a low voltage (e.g., 1 V); the word line of the cell for reading is enabled; and a write instruction of a data item having a predetermined logic level (e.g., zero) is performed at the bit corresponding to the cell for reading. By providing an additional pass transistor connected to each reference bit line (RBL) and an additional reference cell enabling line (REF-EN), the reference cells may also be read directly.
Claims29
A method of reading the current of memory cells in a memory array on a microcontroller chip, the method comprising the steps of:
- supplying a low voltage to a programming voltage supply line of the memory array on the microcontroller chip, the low voltage being insufficient to write to a memory cell;
- performing a write operation to a selected cell of the memory array;
- and
- measuring current flow through the selected cell.
A microcontroller including:
- a programming voltage supply line;
- a memory array having a number of memory cells coupled to the programing voltage supply line;
- means for writing to predetermined cells of the memory;
- and
- means for supplying a low voltage to the programing voltage supply line and for detecting current flow in a selected memory cell of the microcontroller, the low voltage being insufficient to write to the cell.
A microcontroller comprising:
- a processing unit;
- a memory array having a number of memory cells arranged in rows and columns;
- a plurality of data bit lines coupled to the memory array along the columns;
- a programming voltage supply line coupled to the data bit lines;
- an address decoder, coupled to receive inputs from the processing unit, having word lines coupled to the rows of the memory array for selectively enabling rows;
- a data input bus, coupled to the processing unit and to the programming voltage supply line, for selectively enabling columns;
- and
- a pin, coupled to the programming voltage supply line, for coupling a low voltage source and a current detector to the programming voltage supply line, the current detector for measuring the current when the pin is coupled to the low voltage supply, the low voltage being sufficiently low to be insufficient to write to a cell.
A method of testing a microcontroller chip having a processing unit, an address decoder, a memory array having memory cells, and a programming voltage supply line coupled to the memory cells, the method comprising the steps of:
- supplying a low voltage to the programming voltage supply line of the microcontroller, the low voltage being insufficient to write to a memory cell;
- selecting a cell of the array;
- coupling the low voltage to the cell;
- and
- measuring an electrical current in the selected cell.
A microcontroller including:
- a processing unit;
- a memory array having memory cells;
- an address decoder, coupled to the processing unit and the memory array, that receives an address from the processing unit and selects a memory cell corresponding to the address from the memory array;
- and
- means for coupling a low voltage source and a current detector to the memory cell selected by the address decoder, a low voltage from the voltage source being insufficient to write to the memory cell.
Dependencies are inferred from the claim text.