Device for the detection of a high voltage greater than a supply voltage

#The present invention relates to a device for the detection of a high voltage. The device can be applied especially to integrated circuits comprising electrically programmable non-volatile memory elements.

#The programming of non-volatile memory elements requires the use of a high voltage. For example, for an integrated circuit supplied at 2.5 volts, this high voltage reaches about 8 volts. In certain circuits, this high voltage is generated internally using a charge pump.

#In other circuits, this high voltage is applied to an external pin of the integrated circuit. In this case, the customer specification for the integrated circuit gives indications on the required characteristics of this voltage. These characteristics include a nominal value, a range of values around the nominal value, and a timing window of application of this high voltage before internal use. For example, the client specification may indicate that the high voltage has a nominal value of 8 volts in a range of 7.5 to 9 volts, and must be applied in a timing window of 500 nanoseconds to 1 millisecond before it is effectively used internally. The user seeking, for example, write access to a memory element must follow a certain timing sequence to send a write command with the address and the data to be written, and to apply the high voltage.

#Other features and advantages of the invention shall be described in detail in the following description made by way of a non-restrictive indication with reference to the appended drawings, of which:

#FIG. 1 shows a general block diagram of a device according to the present invention;

#FIG. 2 shows a detailed diagram of a first embodiment of the present invention;

#FIG. 1 shows an integrated circuit 1 comprising a detection device 2 according to the present invention. This integrated circuit receives at external terminals, for example, the logic supply voltages Vdd and Gnd and a high voltage Vpp. These voltages are applied to the detection device 2 to detect the application of the high voltage Vpp. This detection device gives a detection signal Out.

#The detection signal is applied in the example to a reshaping and selector switch device 3. The reshaping and selector switch device 3 provides a modified programming voltage Vpp1 to the circuit systems or internal circuits 4 of the integrated circuit at the output when the detection signal Out is activated. For example, these internal circuits may include decoders associated with a non-volatile memory to program or erase cells of this memory.

#The detection device according to the invention is designed to detect the crossing of a voltage threshold of the signal Vpp. This indicates the voltage build-up at an internal high-voltage node NH corresponding to the application of the high voltage Vpp to an external pin of the integrated circuit or by an internal charge pump device. If the voltage is applied with an external pin, as shown in FIG. 1, a protection circuit against electrostatic discharges (not shown) is generally designed and connected in the vicinity of this pin. In particular, the protection circuit is between the pin and the high-voltage node NH.