资 源 简 介
The L3845 is used for MODEM and PABX LineInterface applications. The circuit provides DCloop termination for analog trunk lines. The V/Icharacteristic is equivalent to a fixed voltage drop(zener characteristic) in series with an external resistancethat determines the slope of the DCcharacteristic. An external low voltage electrolyticcapacitor causes the circuit to exibit high impedanceto all AC signal in the voice band frequencyrange (>20 Kohm). The OFF-HOOK status is detectedwhen the Line Current is higher than 8mA. In this condition a constant current generatoris activated to supply an external device (typicallyan optocoupler) without affecting the DC/AC characteristicsof the circuit. An additional function isprovided in order to reduce the DC fixed voltagedrop and the AC impedance (PULSE MODE) Thisfunction can be used to respect some EuropeanCountries specifications during Pulse Dialling Operation.
