MTL7707+ for switch inputs and switched outputs

　　The MTL7707+ is a 2-channel shunt-diode safety barrier similar to the MTL7787+ but with built-in electronic overvolt protection. It is intended primarily for safeguarding a hazardous-area switch controlling a relay, opto-coupler or other safe-area load from an unregulated dc supply in the safe area.

　　The outgoing channel accepts supply voltages up to +35V and is protected against reverse voltages: the return channel is unaffected by voltages up to +250V.

　　In normal operation the protection circuit introduces only a small voltage drop and shunts less than 1mA to earth, so its overall effect is minimal. If the supply voltage exceeds about 27V, however, causing the Zener diodes to conduct – or if the safe-area load has a very low resistance – the supply current is limited automatically to 50mA, protecting the fuse and power supply and enabling the loop to continue working。

　　ADDITIONAL SPECIFICATION

　　Safety description

　　28V 300Ω 93mA, terminals 1 to 3 28V Diode, terminals 2 -4

　　Supply voltage

　　10 to 35V dc with respect to earth

　　Output current

　　Up to 35mA available

　　Maximum voltage drop (at 20ºC, current not limited)

　　Iout x 345Ω + 0.3V, terminals 1 to 3 Iout x 25Ω + 0.9V, terminals 4 to 2

　　Supply current

　　Iout + 1.6mA, supply <26V

　　Limited to 50mA, supply >28V or low load resistance