HT0638 Supertex, Inc., HT0638 Datasheet

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HT0638

Manufacturer Part Number
HT0638
Description
Electronic Line Switch
Manufacturer
Supertex, Inc.
Datasheet
Features
Applications
Typical Application Circuit
Ring
Tip
15Ω maximum switch resistance
Current limiting protection
4 logic control inputs
Operates at 2V input
2µA maximum quiescent current at 100V
Telephone handsets
Fax machines
Answering machines
Auto-dial alarm systems
TPG
LS1
LS2
DP
HKS
HT0638
Electronic Line Switch
H = ON
L = OFF
General Description
The Supertex HT0638 is an integrated, electronic line
switch controllable from four logic-level inputs. This device
is intended as a replacement for mechanical hook switches
and relays in telephones, answering machines, and similar
telecommunications equipment. It switches the positive
(Tip) side of the telephone line using control inputs that are
referenced to the negative (Ring) side of the line. In the off
state, it can hold-off 375 volts. In the on state, the series
resistance is 15Ω maximum. This device provides adjustable
current limiting via an external sense resistor. Three of the
control inputs are general purpose and one is an override
input that forces the switch to an off state regardless of
the state of the other inputs. This override input is useful
for ‘fl ash’ and pulse dialing purposes. Internal pull-up/down
resistors allow the inputs to be driven from single-ended
sources, push-pull sources, or left unconnected.
The HT0638 is powered by the telephone line, and so it is
especially useful in applications where external power is
not available. Due to its low quiescent current, this device
exceeds the on-hook resistance requirements of the telecom
standard EIA-470-A.
Charge Pump
Logic Control
&
TP
CS
GND
9V
+
-
HT0638
Telecom
Voltage
Low
IC

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HT0638 Summary of contents

Page 1

... Internal pull-up/down resistors allow the inputs to be driven from single-ended sources, push-pull sources, or left unconnected. The HT0638 is powered by the telephone line, and especially useful in applications where external power is not available. Due to its low quiescent current, this device exceeds the on-hook resistance requirements of the telecom standard EIA-470-A ...

Page 2

... 100 200 - 300 200 µ 136 µ 136 µ 500 µA 2 HT0638 TPG HKS 8Lead SOIC GND LS2 LS1 4 5 Top View Conditions I = 10µA, HKS, LS1, LS2 open circuit V = 100V, HKS, LS1, LS2, TPG ...

Page 3

... vs. R LIMIT SENSE 350 300 250 200 150 100 50 0 100 200 300 400 500 600 700 800 900 1000 R (ohms) SENSE 3 HT0638 Unit Conditions V --- V --- V --- V --- V --- V --- 4.5V TPG 4.5V TPG Switch State ON ...

Page 4

... SOIC (Narrow Body) LG Package Outline 6.00 ± 0.20 3.90 ± 0.10 1.75 MAX 0.10 - 0.25 Notes: (The package drawing(s) in this data sheet may not refl ect the most current specifi cations. For the latest package outline information go to http://www.supertex.com/packaging.html.) Doc.# DSFP-HT0638 NR111006 4.90 ± 0.10 8 Note 2 1 Top View 1.25 MIN ...

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