Dual SPM Detector

Page 7 of 16

MX641 Preliminary Information

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ã2001 MX-COM, Inc.

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Doc. # 20480115.004

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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

Note (see section 6.1.3) that the maximum load on the master Clock Out pin should not be exceeded.

µController

XTAL

XTAL/CLOCK

"OUTPUT ENABLE"

ADDRESSING

CLOCK

OUT

V

DD

CLOCK

IN

CLOCK

IN

Ch 2

Ch 1

CLOCK

IN

CLOCK

IN

X1

MX641

(used as

Master

Oscillator)

MX641

MX641

MX641

I/O Ports

3 to'N' LINE

DECODER

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

Preset

Level

Output

Select

Output

Enable

Operating Mode

Mode

Sensitivity

Frequency

X

0

0

0

Packet Mode Output;

Serial Data Control (see note)

X

0

1

0

Tone Follower Output;

Serial Data Control (see note)

0

1

0

0

Packet Mode Output;

Fixed Sensitivity

16kHz

1

1

0

0

Packet Mode Output;

Fixed Sensitivity

12kHz

0

1

1

0

Tone Follower Output;

Fixed Sensitivity

16kHz

1

1

1

0

Tone Follower Output;

Fixed Sensitivity

12kHz

X

X

X

1

Tristate Output (High Z)

X = don’t care

Note: Device sensitivity and system frequency must be serially loaded

Table 3: Operating Mode Configuration