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HT18/ HT19 Electronic Telephone Line Switch Features 350V breakdown voltage 18 maximum switch resistance Current limiting protection Operates at 2.3V input General Description The Supertex HT18LG and HT19LG are electronic line switch circuits that replace the mechanical hook switch contact or a discrete hook switch in a telephone handset or modem. They switch the positive side of the telephone line using control inputs that are referenced to the negative side of the line. In their off state, they can withstand 350V on the positive input. In their on state, they have a maximum series resistance of 18. The devices provide current limiting determined by an external resistor. There are three control inputs. The HKS pin turns on the hook switch when connected to the TPG pin. This can be accomplished by using a mechanical switch which closes when the handset is physically off-hook. The LS pin allows a logic signal to turn on the hook switch. The dial pulse, Pin 6, is used to turn the hook switch off for pulse dialing. For the HT18, the dial pulse is active high (DP), whereas for the HT19, it is active low (DP). Applications Telephone handsets Modems Fax machines Answering machines Remote meter reading Telephone interface products Typical Application Circuit TPG Tip TP RSEN Transient Protection HKS HT18 or HT19 CS 15V LS DP/DP Telecom Circuit Ring GND HT18/HVT19 Ordering Information Device HT18 HT19 Package Options 8-Lead SOIC (Narrow Body) HT18LG HT19LG HT18LG-G HT19LG-G -G indicates package is RoHS compliant (`Green') Absolute Maximum Ratings Parameter VTPG, Input line voltage VTP, Output line voltage DP/DP continuous input voltage Storage temperature Junction temperature Soldering temperature Power dissipation 1 Pin Configuration Value TPG 1 8 TP CS DP/DP LS +350V +18V +10V -65C to +150C +150C +300C 0.8W HKS 2 GND 3 NC 4 HT18/ HT19 7 6 5 SO-8 (Top View) Note 1. For HT18, Pin 6 is DP For HT19, Pin 6 is DP Absolute Maximum Ratings are those values beyond which damage to the device may 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 referenced to device ground. Note 1. Distance of 1.6mm from case for 10 seconds. Electrical Characteristics (T =25C unless otherwise specified) J Symbol Parameter Min Typ Max Units Conditions VTPG High voltage positive supply - 250 - 350 2.0 V ITPQ Input leakage current 200 18 18 30 75 100 330 200 30 -30 A ITPG = 500A, HKS, LS, DP/DP = open circuit VTPG = 100V, HKS, LS, DP/DP = open circuit VTPG = 290V, HKS, LS, DP/DP = open circuit VTPG = 17V, ITPG = 180mA, SW = On RSW TPG to TP switch resistance - VTPG = 3.0V, ITPG = 20mA, SW = On VTPG = 2.3V, ITPG = 5mA, SW = On VTPG = 5.0V, SW = On VTPG = 10V, SW = On REXT = 200 1% VHKS = 40V -70V VLS = 3.0V, VDP = 3.0V VDP = 0V ITPG - ITP ILIM IHKS ILS, IDP IDP Bias current ITPG current limiting HKS input current LS and DP logic input current DP output current 188 - A mA A A A 2 HT18/HVT19 Electrical Characteristics Symbol VIL(HKS) VIH(HKS) VIL(LS), VIL(DP) VIH(LS), VIH(DP) TON TOFF Parameter HKS input low HKS input high Input logic low for DP/DP and LS Input logic high for DP/DP and LS Turn on time Turn off time Min 0 2.0 0 1.5 Typ Max 0.2 VTPG 0.2 10 1.0 1.0 Unit V V V V ms ms Conditions VTPG = 3.0V to 70V VTPG = 3.0V to 70V VTPG = 3.0V to 70V VTPG = 3.0V to 70V VTPG = 4.5V VTPG = 4.5V Logic Truth Table HKS H H L or Z L or Z X Z = high impedance, open circuit X = don't care L = logic level low H = logic level high LS1 L or Z H L or Z H X DP L or Z L or Z L or Z L or Z H DP H or Z H or Z H or Z H or Z L Switch State ON ON OFF ON OFF Block Diagram (1) TPG (8) TP (2) HKS H = ON L = OFF (5) LS (6) for HT18 DP (3) (6) for HT19 DP GND (7) Charge Pump and Logic Control CS 3 HT18/HT19 Pin Description Pin Name Description 1 2 3 4 5 6 6 7 8 TPG HKS GND NC LS DP DP CS TP Positive input side of a telephone line, typically Tip side. Hookswitch input. Connect HKS to TPG to turn on the hook switch. Internally pulled low with a high value resistor. Device ground. Negative side of a telephone line, typically Ring side. No Connect. Open Circuit. No internal connections to the device. Line switch input. Input logic high turns on the hook switch. Internally pulled low with a high value resistor. For HT18. Dial pulse input. Input logic high turns off the hook switch. Used for pulse dialing. Internally pulled low with a high value resistor. For HT19. Dial pulse input. Input logic low turns off the hook switch. Used for pulse dialing. Internally pulled high with a high value resistor. Current sense input. An external resistor connected between CS and TP sets the current limit. Positive output side of a telephone line. Zener protection to prevent this output from rising above 18V is required. 8-Lead SOIC (Narrow Body) LG Package Outline 4.90 0.10 8 6.00 0.20 3.90 0.10 Note 2 1 Top View 0.17 - 0.25 1.75 MAX 1.25 MIN 5 - 15 (4 PLCS) 45 0.25 - 0.50 Note 2 0 - 8 0.10 - 0.25 1.27BSC 0.40 - 1.27 0.31 - 0.51 Side View Notes: 1. All dimensions in millimeters. Angles in degrees. 2. If the corner is not chamfered, then a Pin 1 identifier must be located within the area indicated. End View (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to http://www.supertex.com/packaging.html.) Doc.# DSFP-HT18_HT19 A111006 4 |
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