CH1817 Datasheet | Unknown Manufacturer

FEATURES - - - - - - - - - - - - Low Profile, Ultra small size: 1.0” x 1.0” x 0.35” plete DAA function Ring detection Built-in 2-wire to 4-wire conversion Lightweight Multimedia patible +5V operation 1000 VAC isolation 800 Volt surge protection V.32bis/14,400bps, applications UL1459 recognized CH1817-L: Low power consumption and mon mode noise rejection filter - CH1817-LM (special order): Reduced transmit attenuation - CH1817-D: Differential transmission input and 0d B transmission insertion loss. Data Shee FUNCTIONAL DESCRIPTION . Ring Detection. Referring to the block diagram in Figure 1, ining 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 ining 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. ISOLATION SURGE AND PROTECTION CIRCUITRY TIP RING 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 . XMIT RCV RI OFFHK HYBRID 2W/4W CONVERTER 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) Data Sheet 4 U . .. Cermetek Microelectronics, Inc. CH1817 Family of Low Profile DAA...