CH1840
CH1840 is Low Profile Data Access Arrangement (DAA) Modules manufactured by Unknown Manufacturer.
FEATURES
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- Works with all modem chip sets Available in 0 d B, -6 d B, and -9 d B insertion losses Available in extended temperature operation, -40o C to +85o C plete DAA function Voice and data FCC Part 68 registered Registration conveyed to user Hook switch control Ring detection Single +5V operation Pulse dial capability
FUNCTIONAL DESCRIPTION
The operation of the CH1840 can be broken down into the functional blocks shown in Figure 1. 1) Phone line control 2) Billing delay 3) Ring detection 4) Signal Path 5) 2- to 4-wire converter Control inputs and status outputs for the CH1840 are patible with 5 Volt CMOS. See the Electrical Specifications.
Phone Line Control
In the Public Switched Telephone Network (PSTN), the wires from a telephone to the phone pany’s central office (CO) are referred to as the local loop.
Figure 1. CH1840 Functional Block Diagram
© 2000 Cermetek Microelectronics, Inc. Page 1 Document No. 607-0011 Rev. A (5/00)
Drawing current from the local loop signals the central office that the telephone is Off Hook, that is, either answering a call or preparing to place a call. In the CH1840, this function is controlled by the OFFHK signal. When this input is LOW, the CH1840 is On-Hook, indicating to the central office it is not using the line. The CH1840 can pulse dial by toggling the OFFHK input. For data calls, FCC Part 68 rules require silence on the phone line for at least 2 seconds after the call has been pleted to allow central office to exchange billing information. The CH1840 assures conformance to this requirement by...
