An electronic charge retention circuit for time measurement, implanted in an array of EEPROM memory cells, each including a selection transistor in series with a floating-gate transistor, the circuit including, on any one row of memory cells: a first subassembly of at least a first cell, the thickness of the dielectric of the tunnel window of the floating-gate transistor of which is less than that of the other cells; a second subassembly of at least a second cell, the drain and source of the floating-gate transistor of which are interconnected; a third subassembly of at least a third cell; and a fourth subassembly of at least a fourth cell, the tunnel window of which is omitted, the respective floating gates of the transistors of the cells of the four subassemblies being interconnected.