With the LTC1921 from Linear Technology, you’ll be able to monitor two -48-V telecom supplies for undervoltage (-38.5V ±1V) and over voltage (-70V ±1.5V) problems. The MSOP-8 IC provides three separate alarm outputs to drive optocouplers or green LEDs, and meets relevant Telcordia specificiations for performance and accuracy. In addition, the IC monitors the voltage across protective fuses, and indicates when a fuse is blown.
The LTC1921 provides monitoring of two supplies plus associated fuses.
The telecom environment is electrically harsh, thus the LTC1921 withstands ±100VDC faults and 10 µs transients as high as 200V. For operation, you need add just three low-cost, non-critical resistors to this US$2.50 part.
With the LTC1921 from Linear Technology, you’ll be able to monitor two -48-V telecom supplies for undervoltage (-38.5V ±1V) and over voltage (-70V ±1.5V) problems. The MSOP-8 IC provides three separate alarm outputs to drive optocouplers or green LEDs, and meets relevant Telcordia specificiations for performance and accuracy. In addition, the IC monitors the voltage across protective fuses, and indicates when a fuse is blown. 
