Features and Benefits

  • Withstands Transient Voltages Up to 200V/–200V
  • Requires No Precision External Components
  • Independently Monitors Two –48V Supplies for
    • – Undervoltage Faults: –38.5V ±1VMAX
    • – Overvoltage Faults: –70V ±1.5VMAX
  • Accurately Detects Undervoltage Fault Recovery: –43V ±0.5VMAX
  • Monitors Two External Fuses
  • Operates from –10V to –80V
  • Tolerates DC Faults to –100V
  • Tolerates Accidental Supply Reversal to 100V
  • Small Footprint: 8-Lead MSOP Package
  • Specified from –40°C to 85°C

Product Details

The LTC1921 monitors two independent –48V supplies, including their fuses, and drives up to three optoisolators to indicate status, in accordance with standard backplane specifications. Requiring only three noncritical resistors and optoisolators, the LTC1921 replaces multiple voltage comparators, a voltage reference and several precision resistors.

The monitor features dual supply overvoltage and undervoltage detection circuits. The preset trip thresholds include overvoltage, undervoltage and undervoltage recovery that are guaranteed over temperature and meet or exceed common backplane specifications. Additional built-in circuitry detects the condition of supply fuses. Overvoltage and undervoltage detectors ignore fast supply transients, eliminating false detection. The LTC1921 operates from –10V to –80V with a typical power dissipation of less than 10mW.

The LTC1921 is available in 8-pin MSOP and SOIC packages.


  • Telecom Backplanes or Switch Cards
  • Networking Backplanes or Switch Cards
  • High Voltage Fuse Monitoring

Product Lifecycle icon-recommended Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Evaluation Kits (1)

Product Recommendations

LTC1921 Companion Parts

Recommended Related Parts

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ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.

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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.