A hemodialysis catheter, also know as a renal dialysis access catheter penetrates a patients skin at an entrance site which is protected by associated bandaging, all of which needs to be protected from water when the patient takes a shower. A first current mirror circuit provides PTAT currents to the emitters of the first and second transistors, and an operational amplifier maintains the voltage on the emitter of the first transistor of the first transistor stack at the same level as the resistor and sinks a PTAT current from the first current mirror circuit from which the other PTAT currents are mirrored. The profiles are within the inside diameter of the casing string and do not restrict the flowbore of the casing.