LM139J

The LM139J is a military-grade quad differential comparator from Texas Instruments, characterized for operation over the full military temperature range of -55°C to +125°C. It comprises four independent precision voltage comparators in a hermetic CDIP-14 package. Each comparator features an open-collector output capable of sinking up to 16 mA, low input bias current of 25 nA, and an input common-mode range that includes ground. The devices are designed to operate from a single power supply or dual supplies, making them versatile for a wide range of military and industrial applications.

Each of the four comparators in the LM139J compares the voltage at its inverting input (-) against the voltage at its non-inverting input (+). When the non-inverting input is higher than the inverting input plus the offset voltage, the open-collector output transistor turns off (high impedance). When the inverting input exceeds the non-inverting input plus offset, the output transistor turns on and sinks current to ground. The open-collector configuration allows multiple outputs to be wired-AND connected. The input stage uses a differential pair with PNP transistors, enabling the common-mode range to extend to ground even on single supply. A compensation capacitor provides stable operation without external components.

• Military and aerospace systems requiring -55°C to +125°C operation
• Zero-crossing detectors in power line monitoring
• Window comparators for over/under voltage detection
• Relay and lamp driver circuits using open-collector output
• Industrial instrumentation and process control