Datasheet LTC1921 (Analog Devices)

LTC1921 Dual –48V Supply and Fuse Monitor
U FEATURES DESCRIPTIO
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Withstands Transient Voltages Up to 200V/–200V
The LTC®1921 monitors two independent – 48V supplies, ■
Requires No Precision External Components
including their fuses, and drives up to three optoisolators ■ Independently Monitors Two –48V Supplies for to indicate status, in accordance with standard backplane – Undervoltage Faults: –38.5V ±1V specifications. Requiring only three noncritical resistors MAX – Overvoltage Faults: –70V ±1.5V and optoisolators, the LTC1921 replaces multiple voltage MAX ■ Accurately Detects Undervoltage Fault Recovery: comparators, a voltage reference and several precision –43V ±0.5V resistors. MAX ■ Monitors Two External Fuses The monitor features dual supply overvoltage and under- ■ Operates from –10V to –80V voltage detection circuits. The preset trip thresholds in- ■ Tolerates DC Faults to –100V clude overvoltage, undervoltage and undervoltage recovery ■ Tolerates Accidental Supply Reversal to 100V that are guaranteed over temperature and meet or exceed ■ Small Footprint: 8-Lead MSOP Package common backplane specifications. Additional built-in cir- ■ Specified from – 40°C to 85°C cuitry detects the condition of supply fuses. Overvoltage
U
and undervoltage detectors ignore fast supply transients,
APPLICATIO S
eliminating false detection. The LTC1921 operates from –10V to –80V with a typical power dissipation of less than ■ Telecom Backplanes or Switch Cards 10mW. ■ Networking Backplanes or Switch Cards ■ High Voltage Fuse Monitoring The LTC1921 is available in 8-pin MSOP and SOIC pack- ages. , LTC and LT are registered trademarks of Linear Technology Corporation.
U TYPICAL APPLICATIO
– 48V RETURN 47k 47k 47k LOGIC R1 R2 FUSE GOOD SUPPLY 100k 100k –48V LOAD 3 RTN MOC207 1 4 V OUT F A SUPPLY A GOOD SUPERVISOR µP 8 VB LTC1921 MOC207 2 FUSE A 7 5 SUPPLY B GOOD LOGIC FUSE B OUT A COMMON MOC207 6 OUT B R3 47k D1 MURS320 F1 1/4W SUPPLY A –48V 1921 TA01 F2 D2 MURS320 SUPPLY B –48V 1921f 1