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CH1817ET

Family of Low Profile DAA Modules

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CH1817

Family of Low Profile DAA Modules

INTRODUCTION

The CH1817 is a Family of Low Profile Data Access

Arrangement (DAA) Modules. They are compatible

with all modem chip sets. These devices have been

tested to meet or exceed FCC Part 68 requirements

and are Canadian DOC approvable. They are also

recognized by Underwriters Laboratories to UL 1459

Specifications.

The CH1817 modules are ultra small (1.0” x 1.0”

x0.35”) affording an easy integration into space-

sensitive designs, including laptop and hand-held

computer based products. The CH1817 family of

products may be socketed or mounted directly onto a

Printed Circuit Board (PCB). The telephone line

connection is made through TIP and RING to an RJ-11

jack or equivalent.

The CH1817 is intended for use with FAX/modem chip

sets that have a data throughput of up through

V.32bis. For High Speed Applications, Cermetek

recommends the CH1837A.

FEATURES

• Low Profile, Ultra small size: 1.0” x 1.0” x 0.35”

• Complete DAA function

• Ring detection

• Built-in 2-wire to 4-wire conversion

• Lightweight

• Multimedia compatible

• +5V operation

• 1000 VAC isolation

• 800 Volt surge protection

• V.32bis/14,400bps, applications

• UL1459 recognized

• CH1817-L: Low power consumption and Common

mode noise rejection filter

• CH1817-LM (special order): Reduced transmit

attenuation

• CH1817-D: Differential transmission input and 0dB

transmission insertion loss.

FUNCTIONAL DESCRIPTION

Ring Detection. Referring to the block diagram in

Figure 1, incoming ring detection is performed by the

CH1817 and the RI pin is set Low during the 2 second

(typical) ring period and is restored to High for the 4

seconds (typical) between rings. During incoming ring

signal activity, the RI output is pulsed at the same

frequency as the ringing signal, typically 20Hz. Figure

2 contains additional external circuitry which may be

used to provide an envelope indication of the ring

signal. The internal ring detection circuit is designed

to deter false indications due to pulse dialing or noise

on the line.

The RI output of the CH1817 is diode protected.

Therefore, an external pull-up resistor (R>100Kohm)

to +5V may be utilized to activate the ring detection

circuit when the CH1817 is not connected to power.

This can be handy in designs where power

consumption is of concern. When circuited in this

manner, there is virtually no current draw until a ring

signal is present.

RI

Output: Active low

Opto coupler, 30KΩ pull-up

Square wave: 15-68Hz (Typ. 20Hz)

Sensitivity: 38Vrms across Tip & Ring

VCC

ISOLATION

GND

SURGE

AND

PROTECTION

CIRCUITRY

TIP

RING

XMIT

RCV

RI

HYBRID

2W/4W

CONVERTER

OFFHK

OFF-HOOK

SWITCH

RING DET.

Figure 1. CH1817 DAA Functional Block Diagram.

2002 Cermetek Microelectronics, Inc.

Page 1

Document No. 607-0007 Revision B (01/02)

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