Dual SPM Detector
Page 7 of 16
MX641 Preliminary Information
4. General Description
4.1
Xtal/Clock Distribution
The MX641 requires a 3.579545MHz Xtal or clock pulse input. With the exception of the Xtal, all oscillator
components are incorporated on chip. If a Xtal input is employed the Clock Out pin should be directly linked
to the Clock In pin.
To reduce component and layout complexity, the clock requirements of up to 3 additional MX641 microcircuits
may be supplied from a Xtal-driven MX641 acting as the system master clock. With reference to Figure 3, the
clock should be distributed as illustrated and the Xtal/Clock pins of the driven microcircuits should be
connected directly to V
DD
.
Note (see section 6.1.3) that the maximum load on the master Clock Out pin should not be exceeded.
CLOCK
OUT
CLOCK
IN
CLOCK
IN
CLOCK
IN
CLOCK
IN
µController
XTAL/CLOCK
X1
XTAL
MX641
(used as
Master
Oscillator)
Ch 1
Ch 2
V
DD
MX641
MX641
MX641
XTAL/CLOCK
XTAL/CLOCK
XTAL/CLOCK
Ch 1
Ch 1
Ch 2
Ch 2
OUTPUT
ENABLE
Ch 1 OUTPUT
Ch 2 OUTPUT
I/O Ports
Ch 2
Ch 1
3 to'N' LINE
DECODER
"OUTPUT ENABLE"
ADDRESSING
Figure 3: Xtal/Clock Distribution and Output Multiplexing
4.2
Channel Outputs
Channel 1 and Channel 2 outputs operate together under the control of the Output Enable and Output Select
inputs.
Table 3 describes the operations.
The digital output is pin-selectable to one of three modes:
(1) Tone Follower mode: a logic level for the period of a correct decode.
(2) Packet mode: respond/de-respond after a cumulative period of tone or notone in a fixed (intrinsic
hardwired period that is not user controlled) period.
(3) High-impedance output: for device multiplexing.
System
Select
X
X
0
1
0
1
X
X = don’t care
Note: Device sensitivity and system frequency must be serially loaded
Table 3: Operating Mode Configuration
Preset
Level
0
0
1
1
1
1
X
Output
Select
0
1
0
0
1
1
X
Output
Enable
Mode
0
0
0
0
0
0
1
Operating Mode
Sensitivity
Frequency
Packet Mode Output;
Tone Follower Output;
Packet Mode Output;
Packet Mode Output;
Tone Follower Output;
Tone Follower Output;
Serial Data Control (see note)
Serial Data Control (see note)
Fixed Sensitivity
Fixed Sensitivity
Fixed Sensitivity
Fixed Sensitivity
16kHz
12kHz
16kHz
12kHz
Tristate Output (High Z)
ã
2001 MX-COM, Inc.
www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054
Doc. # 20480115.004
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
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