OfficeServ 7100 Service Manual© SAMSUNG Electronics Co., Ltd. 2-59Switch Detection PartA visitor can call the person in the inside by pressing the switch on the door box.The DPIM detects if this switch was pressed, with a photo coupler, and enters in the MCUport 46(No. 15 pin). At this time, the MCU sends the data to the D-channel of the PCMtransfer chip(TP 3406, U5).The system, which received this data, sends a signal to the port, which was already specified,to enable the calling.This signal for detecting the switch can consist of two lines because it is sent through thecenter tap of the matching trans(T5692), and even though the power of +5 V is given to thetrans, the trans is not damaged.+12 V Generating PartThe DPIM uses the step up DC converter(LT1109, U11) that generates +12 V in the simplesurrounding circuit by the +5 V power being entered. LT1109-12 displays +12 V 60 mA bythe input of +5 V.The 33 uH(L2) inductor is for generating the switching, and the 47 uF/35 V(C7) capacitoris for the load of the switch, and the 33 uH(L1) inductor of the output end is for decreasingthe switching ripple noise. Also, the poly switch of the +12 V output end is for prohibitingthe overcurrent from flowing when the +12 V line, which is connected to the door box, isshortened.Pin Connectory Door LockModular pin(6P6C) 1, 6: Dry contact(relay), Normal Open.Figure 2.35 Pin Connection of DPIMy Door PhoneModular pin(6P4C) 1: L1(The L1 and L2 line is limited to +5 V for detecting a switchcontact.)− No. 2 pin: L2− No. 3 pin: P+(+12 V)− No. 4 pin: P-(GND)1 2 3 41 2 3 45 6
