HT9020B

Call Progress Tone Detector

Block Diagram

Pin Assignment

Rev. 1.20

1

March 31, 2003

Features

0~

General Description

The HT9020B call progress tone detector is a telecom

peripheral for Auto-dialing system use.

Switched capacitors technology is implemented into the

chip to get good performance characteristics of band

pass filter in the range of 305 to 640Hz call progress

tone which is dual tone multi-frequency signal.

When it detected CPT signal then it generates relative

envelopes for external microcontroller decision to finish

different kinds of CPT signal detection such as dial tone,

busy tone, ring-back tone and reorder tone.

3 2 7 6 8 H z

O s c i l l a t o r

C l o c k

G e n e r a t o r

B a n d p a s s

. i l t e r

E N V

V R E .

L e v e l

S e n s e C K T

V D D

V S S

E N

V R E .

G e n e r a t o r

D i g i t a l

C o n t r o l C K T

S I N

X 1

X 2

1

2

3

4

8

7

6

5

H T 9 0 2 0 B

8 D I P - A

E N V

V R E .

S I N

V S S

V D D

E N

X 2

X 1