CM1481 Datasheet, PDF (14/24 Pages) ON Semiconductor – 2-Channel EMI Filter with ESD Protection for Headsets/Speakers

Functional Descriptions ......
Single or
Dual Button
Operation
The CM1481 can be configured to one of two modes of user control.
Dual Button mode. The ‘Quiet/Open’ switch toggles the ‘Quiet/Open’ (mute) function; the
‘Tx Call’ switch initiates a Selcall ‘Tx Call’.
If it is required to operate in a unit with no local means of ‘Quiet/Open’ operation, this
dual-button mode should be configured but the ‘Quiet/Open’ input not connected
internally.
Single Button mode. A single switch (push-button) connected to either ‘Quiet/Open’ or
‘Tx Call’ inputs controls both Mute and Selcall operations.
A “press” of less than 1-second will toggle the ‘Quiet/Open’ condition; a “press” of more
than 1-second will initiate a Selcall.
Both inputs can be configured to active “High” or “Low” polarities; with reference to the
CM1481, both inputs are connected, on-board, to the positive supply rail (V_DD) via 47kΩ
pullup resistors.
For an active “Low” input, the switches should be connected directly to 0V (GND).
For an active “High” requirement, the on-board pullup resistors must be considered.
Configured as Operation:
Quiet/Open
+ve
supply rail
Tx Call
pullup resistors
Fig.7 Operating Button Connections
Automatic
Number
Identification
(ANI)
Each unit is assigned a unique ANI code which enables identification of a transmission. In
the CM1481 this code is programmable, both by initial configuration and by over-air
re-configuration, as the ANI address.
When enabled the ANI code is transmitted at the beginning (leading) and/or the end
(trailing) of a transmission. In the CM1481 the ANI operation is selectable by configuration
to either OFF, Lead, Trail, or Lead and Trail.
If the PTT Time-Out function is activated, a trailing ANI (if configured) is transmitted
before shut-down.
Configured as ANI Mode: and ANI Address:
PTT In
(active "low")
Tx ON
(active "low")
Mic key reset; signifying
end of conversation
Tx remains keyed
for ANI period
Tone Out
Leading
ANI
Fig.8 ANI Functional Diagram
14
Trailing
ANI