HT18 Electronic Telephone Line Switch Features General Description The Supertex HT18LG is an electronic line switch circuit that 350V breakdown voltage replaces the mechanical hook switch contact or a discrete 18 maximum switch resistance hook switch in a telephone handset or modem. It switches Current limiting protection the positive side of the telephone line using control inputs Operates at 2.3V input that are referenced to the negative side of the line. In its off state, it can withstand 350V on the positive input. In its on Applications state, it has a maximum series resistance of 18. Telephone handsets The device provides current limiting determined by an Modems external resistor. There are three control inputs. The HKS Fax machines pin turns on the hook switch when connected to the TPG pin. This can be accomplished by using a mechanical switch Answering machines which closes when the handset is physically off-hook. The Remote meter reading LS pin allows a logic signal to turn on the hook switch. The Telephone interface products dial pulse, Pin 6, is used to turn the hook switch off for pulse dialing. The dial pulse (DP) is active high. Typical Application Circuit TP TPG Tip R SEN CS Telecom HT18 Transient Circuit HK S 15 V Protection LS DP Ring GN D 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: 408-222-8888 www.supertex.comHT18 Ordering Information Package Option 8-Lead SOIC (Narrow Body) Device 4.90x3.90mm body 1.75mm height (max) 1.27mm pitch HT18 HT18LG-G -G indicates package is RoHS compliant (Green) Pin Conguration Absolute Maximum Ratings TPG 1 8 TP Parameter Value HKS 2 7 CS V , Input line voltage +350V GND 3 6 DP TPG V , Output line voltage +18V NC 4 5 LS TP DP continuous input voltage +10V 8-Lead SOIC (Narrow Body) (LG) (top view) Storage temperature -65C to +150C Junction temperature +150C Product Marking Soldering temperature* +300C Y = Last Digit of Year Sealed YYWW WW = Week Sealed Power dissipation 0.8W HT18 L = Lot Number Absolute Maximum Ratings are those values beyond which damage to the device may LLLL = Green Packaging occur. Functional operation under these conditions is not implied. Continuous operation of the device at the absolute rating level may affect device reliability. All voltages are Package may or may not include the following marks: Si or referenced to device ground. 8-Lead SOIC (Narrow Body) (LG) * Distance of 1.6mm from case for 10 seconds. Electrical Characteristics (T = 25C unless otherwise specied) A Sym Parameter Min Typ Max Units Conditions V High voltage positive supply - - 350 V I = 500A, HKS, LS, DP = open circuit TPG TPG - - 2.0 V = 100V, HKS, LS, DP = open circuit TPG I Input leakage current A TPG - - 200 V = 290V, HKS, LS,DP = open circuit TPG - - 18 V = 17V, I = 180mA, SW = on TPG TPG R TPG to TP switch resistance - - 18 V = 3.0V, I = 20mA, SW = on SW TPG TPG - - 30 V = 2.3V, I = 5.0mA, SW = on TPG TPG - - 75 V = 5.0V, SW = on TPG I - I Bias current A TPG TP - - 100 V = 10V, SW = on TPG I I current limiting 188 250 330 mA R = 200 1% LIM TPG EXT I HKS input current - - 200 A V = 40 to 70V HKS HKS I , I LS and DP logic input current - - 30 A V = 3.0V, V = 3.0V LS DP LS DP V HKS input low 0 - 0.2 V V = 3.0 to 70V IL(HKS) TPG V HKS input high 2.0 - V V V = 3.0 to 70V IH(HKS) TPG TPG V ,V Input logic low for DP and LS 0 - 0.2 V V = 3.0 to 70V IL(LS) IL(DP) TPG V ,V Input logic high for DP and LS 1.5 - 10 V V = 3.0 to 70V IH(LS) IH(DP) TPG T Turn-on time - - 1.0 ms V = 4.5V ON TPG T Turn-off time - - 1.0 ms V = 4.5V OFF TPG 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: 408-222-8888 www.supertex.com 2