Apparatus for powering down electronic circuits

A bias block switching unit is responsive to a power down control signal for switching between first and second states thereof, being operatively coupled to a reference voltage and coupled to a first supply voltage. A first switch is responsive to the power down control signal for switching between first and second states thereof. The first switch provides an output signal. A first switched constant current unit is coupled to the first switch and a first supply voltage. A first switched constant current unit has a first state for providing a constant current output and a second state for providing substantially no current. The first switched constant current unit is responsive to a bias signal for switching between first and second states thereof. The bias signal is outputted from the bias block switching unit. A first voltage follower receives an input signal, is operatively coupled to a second voltage supply and operatively coupled to the first switch. An advantage is only permitting parasitic current during power-down operation.