Patent ID: 6867624

Claim:
A voltage level monitoring circuit, comprising: a first reference current source ( 5 ) for generating a first reference current (I ref1 ) and comprising a transistor ( 50 ); a second reference current source ( 6 ) for generating a second reference current (I ref2 ); a controllable switch ( 7 ); a monitoring current source ( 4 ) for generating a monitoring current (I M ) derived from a voltage (V M ) to be measured, the monitoring current source including: a primary current source ( 41 ) for generating a primary current (I p ) said transistor ( 50 ) having a control terminal connected to a control terminal of said primary current source ( 41 ), a first terminal connected directly to a first terminal of said primary current source ( 41 ), and a second terminal coupled to a first current input ( 11 ), a secondary current source ( 42 ) for generating the monitoring current(I M ), and a process sensitive resistor ( 49 ) connected in series with the primary current source ( 41 ); and a comparator device ( 10 ) including said first current input ( 11 ) being coupled for receiving the first reference current (I ref1 ) in response to the controllable switch ( 7 ) being non-conductive, and for receiving both the first reference current (I ref1 ) and second reference current (I ref2 ) in response to the controllable switch ( 7 ) being conductive, a second current input ( 12 ) coupled for receiving the monitoring current (I M ), and at least one measuring signal output ( 13 ), wherein the comparator device ( 10 ) is arranged for comparing the currents received at its two current inputs ( 11 , 12 ) and for generating at the measuring signal output ( 13 ) a measuring signal (S) with a first value when the current received at its second current input ( 12 ) is less than the current received at its first current input ( 11 ), and with a second value when the current received at its second current input ( 12 ) is more than the current received at its first current input ( 11 ).