3

HT19

Supertex inc.

www.supertex.com

Doc.# DSFP-HT19

B031414

Logic Truth Table

Z = high impedance, open circuit

X = irrelevant

L = logic level low

H = logic level high

Block Diagram

HKS

LS

DP

Switch State

H

L or Z

H or Z

ON

H

H

H or Z

ON

L or Z

L or Z

H or Z

OFF

L or Z

H

H or Z

ON

X

X

L

OFF

TPG

TP

CS

GND

HKS

LS

DP

H = ON

L = OFF

(1)

(2)

(5)

(6)

(8)

(7)

(3)

Charge Pump

and

Logic Control

Pin Description

Pin Name 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

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.