Patent ID: 11863355
Assignee: ARONIX LLC
Field: Medical technology (Instruments)
Classification: CPC A  H  B | IPC A  H

Claim 6:
7. A fail-safe differential receiver having single differential input disconnect detection with latchable control signal interrupt capability comprising:
a first voltage reference;
a second voltage reference;
a differential amplifier comprises a receiver output and receives an IN+ input, and an IN− input;
a first voltage follower operational amplifier comprises a first op-amp output and receives the receiver output;
a rectifier peak detector comprises a peak output and receives the first op-amp output;
a second voltage follower operational amplifier comprises a second op-amp output and receives the peak output;
a window comparator comprises a window compared output and receives the second op-amp output, a first reference voltage, and a second reference voltage;
a latch-capable combinational logic device receives the window compared output and the receiver output, the latch-capable combinational logic device comprises a latch and a control signal that is switched to a normal operating state until at least one of the following is detected:
when the IN+ input is open (not connected) the control signal is latched to the fault condition state;
when the IN− input is open (not connected) the control signal is latched to the fault condition state;
when the IN+ input and IN− input are connected by a first resistance, that is configured as an undriven parallel termination, the control signal is latched to the fault condition state;
when the IN+ input is shorted to Vcc or GND the control signal is latched to the fault condition state;
when the IN− input is shorted to Vcc or GND the control signal is latched to the fault condition state;
when the IN+ input and the IN− input are shorted together the control signal is latched to the fault condition state; and
when only one of the IN+ input or the IN− input is intermittently open and reconnected the control signal is latched to the fault condition state;

wherein the receiver output is applied to a Vout output as long as the control signal is in the normal operating state, and on first occurrence of the fault condition state the latch latches blocking the receiver output from being applied to the Vout output until the latch is reset.