CH1817
Family of Low Profile DAA Modules
INTRODUCTION
FEATURES
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.
• 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
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.
• 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
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.
• 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, 30K
Ω pull-up
Square wave: 15-68Hz (Typ. 20Hz)
OFFHK
XMIT
RCV
RI
RING
TIP
GND
VCC
RING DET.
OFF-HOOK
SWITCH
SURGE
AND
PROTECTION
CIRCUITRY
HYBRID
2W/4W
CONVERTER
ISOLATION
Figure 1. CH1817 DAA Functional Block Diagram.
Sensitivity: 38Vrms across Tip & Ring
2002 Cermetek Microelectronics, Inc.
Page 1
Document No. 607-0007 Revision B (01/02)
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