SUPERTEX HT18LG

HT18
HT19
Electronic Telephone Line Switch
Ordering Information
Package Option
Switch Resistance
Dial Pulse Pin
DP/DP
SO-8
Breakdown Voltage
350V
18Ω
Active High
HT18LG
350V
18Ω
Active Low
HT19LG
Features
General Description
❏ 350V breakdown voltage
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 the off state,
they can withstand 350V on the positive input. In the on state
their series resistances are 18Ω maximum. 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).
❏ 18Ω maximum switch resistance
❏ Current limiting protection
❏ Operates at 2.0V input
Applications
❏ Telephone handsets
❏ Modems
❏ Fax machines
❏ Answering machines
❏ Remote meter reading
❏ Phone interface products
Pin Configuration
Absolute Maximum Ratings
VTPG, Input line voltage
+350V
TPG
1
8
TP
VTP, Output line voltage
+18V
HKS
2
7
CS
DP/DP continuous input voltage
+10V
GND
3
6
DP/DP *
Storage temperature
–65°C to +150°C
N/C
4
5
LS
Junction temperature
+150°C
Soldering temperature*
+300°C
top view
0.8 Watt
SO-8
Power dissipation
Notes: All voltages are referenced to ground.
*Distance of 1.6mm from case for 10 seconds.
* For HT18, Pin 6 is DP.
For HT19, Pin 6 is DP.
Note: See Package Outline section for dimensions.
12/13/01
Supertex Inc. does not recommend the use of its products in life support applications and will not knowingly sell its products for use in such applications unless it receives an adequate "products liability
indemnification insurance agreement." Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of devices determined to be defective due to
workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications
are subject to change without notice. For the latest product specifications, refer to the
1
Supertex website: http://www.supertex.com. For complete liability information on all Supertex products, refer to the most current databook or to the Legal/Disclaimer page on the Supertex website.
HT18/HT19
Electrical Characteristics
(Over operating supply voltages unless otherwise specified, TA = 0°C to +50°C)
Symbol
Parameter
VTPG
High voltage positive supply
ITPG
Input leakage current
Min
Typ
Max
Unit
350
V
2.0
µA
Conditions
ITPG = 500µA, HKS, LS,
DP/DP = open circuit
VTPG = 100V, HKS, LS,
DP/DP = open circuit
200
VTPG = 290V, HKS, LS,
DP/DP = open circuit
18
VTPG=17V, ITPG=180mA, SW= On
TPG to TP switch resistance
RSW
18
Ω
30
ITPG-ITP
Bias current
50
100
ILIM
ITPG current limiting
IHKS
188
VTPG=2.0V, ITPG=5mA, SW= On
µA
VTPG = 5.0V, SW = On
VTPG = 10V, SW = On
313
mA
REXT = 158Ω ± 1%
HKS input current
200
µA
VHKS = 40V to 70V
ILS , IDP
LS and DP logic input current
30
µA
VLS = 3.0V, VDP = 3.0V
IDP
DP logic input current
-30
µA
VDP = 0V
VIL(HKS)
HKS input low
0.2
V
VTPG = 3.0V to 70V
VIH(HKS)
HKS input high
VTPG
V
VTPG = 3.0V to 70V
VIL(LS),
VIL(DP)
Input logic low for DP/DP and LS
0
0.2
V
VTPG = 3.0V to 70V
VIH(LS),
VIH(DP)
Input logic high for DP/DP and LS
1.5
10
V
VTPG = 3.0V to 70V
TON
Turn on time
1.0
ms
VTPG = 4.5V
TOFF
Turn off time
1.0
ms
VTPG = 4.5V
0
2.0
250
VTPG=3.0V, ITPG=20mA, SW= On
Truth Table
HKS
LS
DP
DP
Switch State
H
L or Z
L or Z
H or Z
ON
H
H
L or Z
H or Z
ON
L or Z
L or Z
L or Z
H or Z
OFF
L or Z
H
L or Z
H or Z
ON
X
X
H
L
OFF
Z = high impedance, open circuit
X = don’t care
L = logic level low
H = logic level high
2
HT18/HT19
Block Diagram
TPG
(8)
(1)
TP
(2)
HKS
H = ON
L = OFF
LS
(5)
(7)
Charge Pump
&
Logic Control
CS
(6) for HT18
DP
(3)
DP
(6) for HT19
GND
Pin Description
Pin # Symb
Description
1
TPG
Positive input side of a telephone line, typically Tip side.
2
HKS
Hookswitch input. Connect HKS to TPG to turn on the hook switch. Internally pulled low with a high value resistor.
3
GND
Device ground. Negative side of a telephone line, typically Ring side.
4
NC
No Connect. Open Circuit. No internal connections to the device.
5
LS
Line switch input. Input logic high turns on the hook switch. Internally pulled low with a high value resistor.
6
DP
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.
6
DP
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.
7
CS
Current sense input. An external resistor connected between CS and TP sets the current limit.
8
TP
Positive output side of a telephone line. Zener protection to prevent this output from rising above 18V is required.
Typical Application Circuit
TPG
TP
Tip
RSEN
Transient
Protection
HKS
HT18
or
HT19
CS
15V Telecom
Circuit
LS
Ring
DP/DP
GND
12/13/010
©2001 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.
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1235 Bordeaux Drive, Sunnyvale, CA 94089
TEL: (408) 744-0100 • FAX: (408) 222-4895
www.supertex.com