HT18 Просмотр технического описания (PDF) - Supertex Inc

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производитель

HT18

Electronic Telephone Line Switch

Supertex Inc 

HT18/ HT19

Electronic Telephone Line Switch

Features

► 350V breakdown voltage

► 18Ω maximum switch resistance

► Current limiting protection

► Operates at 2.3V input

Applications

► Telephone handsets

► Modems

► Fax machines

► Answering machines

► Remote meter reading

► Telephone interface products

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

18Ω.

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).

Typical Application Circuit

Tip

Transient

Protection

Ring

TPG

TP

RSEN

HT18

HKS

or

CS

HT19 LS

15V Telecom

Circuit

DP/DP

GND

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