Datasheet MX641DW, MX641P Datasheet (MX COM)

DATA BULLETIN

MX641

Dual SPM Detector

Features Applications

x Two (12kHz / 16kHz) SPM Detectors on a

Single Chip

x Detects 12 or 16kHz SPM Frequencies
x ‘Controlled’ (PC) & ‘Fixed’ Signal Sensitivity

Modes

x Selectable Tone Follower or Packet Mode

Outputs

x High Speech-Band Rejection Properties
x ‘Output Enable’ Multiplexing Facility

XTAL/CLOCK

XTAL

Ch1AMPOUT

Ch1 AMP IN (-)

Ch1 AMP IN (+)

PRESET LEVEL

CHIP SELECT
SERIAL

DATA

SERIAL
CLOCK

SYSTEM SELECT

Ch2 AM PIN (-)

Ch2 AMP IN (+)

Ch2AMPOUT

­+

Ch 1

INPUT

AMPLIFIER

SERIAL
INPUT
LOGIC

Ch 2

INPUT

AMPLIFIER

­+

XTAL/CLOCK
GENERATOR

Ch 1

BANDPASS

FILTER

GAIN

ADJUST

LEVEL/
SYSTEM
SETTING

GAIN

ADJUST

Ch 2

BANDPASS

FILTER

COMPARATOR

THRESHOLD

COMPARATOR

THRESHOLD

CLOCK OUT CLOCK IN

BUFFER

Ch 1

COMPARATOR

­+

INTERNAL

12kHz/16kHz

SYSTEM

INTERNAL

+

-

Ch 2

COMPARATOR

x Call Charge Applications on PABX Line

Cards

x Remote Telephone Applications

CLOCK

DIVIDERS

12kHz/16kHz

PULSE

GENERATOR

AND

DIVIDER

CHANNEL 1

CHANNEL 2

PULSE

GENERATOR

AND

DIVIDER

SYSTEM

PULSE

MEASUREMENT

LOGIC

PULSE

MEASUREMENT

LOGIC

TONE FOLLOWER

PULSE

LENGTH

LOGIC

PULSE

LENGTH

LOGIC

TONE FOLLOWER

PRELIMINARY INFORMATION

V

DD

V

OUTPUT
SELECT

CIRCUITS

OUTPUT
SELECT

CIRCUITS

V

Ch 1

OUTPUT

OUTPUT
ENABLE

OUTPUT
SELECT

Ch 2

OUTPUT

BIAS

SS

MODE

MODE

INTERNAL

CLOCKS

PACKET

MODE

12kHz/16kHz

SYSTEM

PACKET

MODE

The MX641 is a low-power, system-selectable Dual Subscriber Pulse Metering (SPM) Detector designed to indicate the
presence, on a telephone line, of either 12kHz or 16kHz telephone call-charge frequencies. It is designed for PBX and
PABX line-card and remote telephone installations. Under PProcessor control via a common serial interface, each
channel of the MX641 will detect call-charge pulses from a telephone line and provide a digital output for recording, billing
or security purposes. A common set of external components and a stable 3.579545MHz Xtal/clock input ensures that the
MX641 adheres accurately to most national “Must and Must-Not” decode band-edges and threshold levels. For non­PProcessor systems a preset sensitivity/system input allows external channel level and system setting

The digital output is pin-selectable to one of three modes:
(1) Tone Follower mode: 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.

The MX641 requires a 5V supply and is available in the following packages: 24-pin SOIC (MX641DW) and 24-pin PDIP
(MX641P).

© 1998 MX

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

xCOM Inc. www.mxcom.com Tele: 800 638-5577 910 744-5050 Fax: [phone] Doc. # 20480115.003

Dual SPM Detector 2 MX641 PRELIMINARY INFORMATION

CONTENTS

Section Page

1. Block Diagram.................................................................................................................................. 3

2. Signal List......................................................................................................................................... 4

3. External Components...................................................................................................................... 6

4. General Description......................................................................................................................... 7

4.1 Xtal/Clock Distribution............................................................................................................................... 7

4.2 Channel Outputs....................................................................................................................................... 7

4.3 Sensitivity Setting...................................................................................................................................... 8

4.3.1 Controlled Sensitivity Setting.............................................................................................................................8

4.3.2 Fixed Sensitivity Setting....................................................................................................................................11

5. Applications .................................................................................................................................... 12

5.1.1 Input Configurations..........................................................................................................................................12

5.1.2 Protection Against High Voltages .....................................................................................................................12

5.1.3 Aliasing .............................................................................................................................................................12

6. Performance Specification............................................................................................................. 13

6.1 Electrical Specifications ........................................................................................................................... 13

6.1.1 Absolute Maximum Ratings..............................................................................................................................13

6.1.2 Operating Limits................................................................................................................................................13

6.1.3 Operating Characteristics .................................................................................................................................13

6.2 Timing ...................................................................................................................................................... 15

6.3 Packages ................................................................................................................................................. 16

MXxCOM, Inc. reserves the right to change specifications at any time and without notice.

© 1998 MXxCOM Inc. www.mxcom.com Tele: 800 638-5577 910 744-5050 Fax: [phone] Doc. # 20480115.003

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Dual SPM Detector 3 MX641 PRELIMINARY INFORMATION

1. Block Diagram

DDVBIASVSS

V

CLOCKS

INTERNAL

CLOCK

DIVIDERS

TONE FOLLOWER

SYSTEM

12kHz/16kHz

Ch 1

MODE

OUTPUT

OUTPUT

PULSE

PULSE

MEASUREMENT

PULSE

GENERATOR

SELECT

CIRCUITS

LOGIC

LENGTH

LOGIC

AND

DIVIDER

MODE

PACKET

CHANNEL 1

ENABLE

OUTPUT

SYSTEM

12kHz/16kHz

SELECT

OUTPUT

CHANNEL 2

MODE

PACKET

SELECT

OUTPUT

CIRCUITS

LOGIC

PULSE

LENGTH

LOGIC

PULSE

MEASUREMENT

AND

PULSE

DIVIDER

GENERATOR

Ch 2

OUTPUT

TONE FOLLOWER

MODE

CLOCK OUT CLOCK IN

XTAL/CLOCK

XTAL/CLOCK

BUFFER

GENERATOR

XTAL

SYSTEM

12kHz/16kHz

-

Ch 1

COMPARATOR

Ch1AMPOUT

+

INTERNAL

THRESHOLD

COMPARATOR

LEVEL/

SERIAL

DATA

SERIAL

SYSTEM

SETTING

INPUT

LOGIC

Ch 1

FILTER

BANDPASS

-

Ch1 AMP IN (-)

GAIN

ADJUST

Ch 1

INPUT

+

AMPLIFIER

PRESET LEVEL

Ch1 AMP IN (+)

CHIP SELECT

SERIAL

CLOCK

INTERNAL

THRESHOLD

COMPARATOR

GAIN

Ch 2

SYSTEM SELECT

ADJUST

INPUT

AMPLIFIER

-

+

Ch 2

-

Ch2 AMP IN (-)

BANDPASS

+

FILTER

Ch 2

COMPARATOR

Ch2AMPOUT

Ch2 AMP IN (+)

Figure 1: Block Diagram

© 1998 MXxCOM Inc. www.mxcom.com Tele: 800 638-5577 910 744-5050 Fax: [phone] Doc. # 20480115.003

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Dual SPM Detector 4 MX641 PRELIMINARY INFORMATION

2. Signal List

Pin No. Name Type Description

1 Xtal/Clock input The input to the on-chip clock oscillator; for use with a 3.579545MHz Xtal in

conjunction with the Xtal output; circuit components are on-chip. When using a
Xtal input, the Clock Out pin should be connected directly to the Clock In pin. If
a clock pulse input is used at the Clock In pin, this (Xtal/Clock) pin must be
connected directly to V

frequency distribution.

2

XTAL

output The output of the on-chip clock oscillator inverter.

3 Clock Out output The buffered output of the on-chip-clock oscillator inverter. If a Xtal input is

used, this output should be connected directly to the Clock In pin. This output
can support up to 3 additional MX641 ICs. See Figure 3 for details of clock
frequency distribution.

4 Clock In input The 3.579545 clock pulse input to the internal clock dividers. If an externally

generated clock pulse input is used, the Xtal/Clock input pin should be
connected to V

5

Output Enable

input For multi-chip output multiplexing; controls the state of both Ch1 and Ch2

DD

.

outputs. When this input is placed high (logic '1') both outputs are set to a high
impedance. When placed low (logic '0') both outputs are enabled.

6 Ch 2 Output output The digital output of the Channel 2 SPM detector when enabled. The format of

the signal at this pin, in common with Ch 1, is selectable to either
'Tone Follower' or 'Packet' mode via the Output Select input.

7 Ch 1 Output output The digital output of the Channel 1 SPM detector when enabled. The format of

the signal at this pin, in common with Ch 2, is selectable to either
'Tone Follower' or 'Packet' mode via the Output Select input.

8V

BIAS

power The output of the on-chip analog bias circuitry. Held internally at VDD/2, this

pin should be decoupled to V

9 Ch 1 Amp Out output The output of the Channel 1 Input Amplifier. See Figure 2 and Figure 8.

10 Ch 1 Amp In (-): input The negative input to the Channel 1 Input Amplifier. See Figure 2 and Figure

8.
11 Ch 1 Amp In (+): input The positive input to the Channel 1 Input Amplifier. See Figure 2 and Figure 8.
12 V

SS

power Negative supply (GND).

13 N/C No internal connection; leave open circuit.
14 Ch 2 Amp In (+): input The positive input to the Channel 2 Input Amplifier. See Figure 2 and Figure 8.
15 Ch 2 Amp In (-): input The negative input to the Channel 2 Input Amplifier. See Figure 2 and Figure

8.
16 Ch 2 Amp Out output The output of the Channel 2 Input Amplifier. See Figure 2 and Figure 8.
17 Output Select input A logic input to set the Channel 1 and Channel 2 output modes. When high

(logic '1'), the outputs are in the Tone Follower mode; when low (logic '0'), the
outputs are in the Packet mode.

18 Preset Level input A logic input to set the sensitivity mode of the MX641. When high (logic '1'),

both channels are in the Fixed Sensitivity mode. The external components
govern the input sensitivity; the System Select input selects 12kHz or 16kHz
operation. When low (logic '0'), both channels are in the Controlled Sensitivity
mode. Device sensitivities and system selection are via the Chip Select/Serial
Data/Serial Clock inputs. This input has an internal pullup resistor on chip
(Fixed Sensitivity Mode).

19

Chip Select

input The Chip Select input for use in data loading when using the MX641 in the

Controlled Sensitivity mode (see Figure 9). The device is selected when this
input is set low (logic '0'). When the MX641 is in the Fixed Sensitivity mode
this input should be connected to either V

(see Figure 2). See Figure 3 for details of clock

DD

(see Figure 2).

SS

or VDD.

SS

© 1998 MXxCOM Inc. www.mxcom.com Tele: 800 638-5577 910 744-5050 Fax: [phone] Doc. # 20480115.003

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Dual SPM Detector 5 MX641 PRELIMINARY INFORMATION

Pin No. Name Type Description

20 Serial Clock input The Serial Clock input for use in data loading when using the MX641 in the

Controlled Sensitivity mode (see Figure 9). Data is loaded to the MX641 on
this clock's rising edge. When the MX641 is in the Fixed Sensitivity mode this
input should be connected to either V

or VDD.

SS

21 Serial Data input The Serial Data input for use in data loading when using the MX641 in the

Controlled Sensitivity mode (see Figure 9 and Table 4). When the device is in
the Fixed Sensitivity mode this input should be connected to either V

or VDD.

SS

22 System Select input In the Fixed Sensitivity mode this pin selects the system frequency. High (logic

‘1’) = 12kHz; Low (logic ‘0’) = 16kHz. In the Controlled Sensitivity mode this pin
is inactive and may be left unconnected. This pin has an internal pullup

resistor on chip.
23 N/C No internal connection; leave open circuit.
24 V

DD

power Positive supply rail; a single, stable power supply is required. Critical levels

and voltages within the MX641 are dependent upon this supply. This pin

should be decoupled to V

by a capacitor mounted close to the pin

SS

Table 1: Signal List

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4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Dual SPM Detector 6 MX641 PRELIMINARY INFORMATION

3. External Components

V

DD

If you use a Clock Pulse input:

- Remove Xtal (X )

- Connect Pin 1 to V

- Do not short Pins 3 & 4

- Input clock pulses to CLOCK IN
See Figure 3

1

DD

CLOCK IN

C3

C4

C2

CH1 AMP IN (-)

CH1 AMP IN (+)

R8

XTAL/CLOCKXTAL/CLOCK

X1

XTAL

CLOCK

OUTPUT ENABLE

CH2 OUTPUT
CH1 OUTPUT

CH1 AMP OUT

R2

OUT

IN

V

R1

R4

BIAS

R3

V

SS

1

2
3
4
5
6

MX641

7
8
9

10
11
12

24
23
22

21
20
19

18
17
16
15
14
13

V

DD

SYSTEM SELECT
SERIAL DATA
SERIAL CLOCK
CHIP SELECT
PRESET LEVEL
OUTPUT SELECT

CH2 AMP OUT

R7

CH2 AMP IN (-)

R6

CH2 AMP IN (+)

R5

C1

V

DD

C5

C6

Figure 2: Recommended External Components

R1
R2
R3 Note 1
R4 Note 1
R5
R6
R7 Note 1
R8 Note 1

68k

68k:
750k:
750k:

68k:

68k:
750k:
750k:

± 1% C1 1.0µF ±20%

:

±1% C2 1.0µF ±20%
±1% C3 270pF ±5%

±1% C4 270pF ±5%
± 1% C5 270pF ±5%
± 1% C6 270pF ±5%

±1%

±1% X1 Note 2, 3 3.579545MHz

Table 2: Recommended External Components

Note:

1. Fixed Sensitivity Setting: when calculating/selecting gain components, R3,

R4, R7 and R8 should always be

greater than or equal to 100k:.

2. For best results, a crystal oscillator design should drive the clock inverter input with signal levels of at least 40% of
, peak to peak. Tuning fork crystals generally cannot meet this requirement. To obtain crystal oscillator design

V

DD

assistance, consult your crystal manufacturer.

3. The on-chip crystal circuitry includes a feedback resistor (nominally 2M:) between pins 1 & 2 and load capacitors

on pins 1 & 2 (nominally 10pF each, excluding package and board parasitics).

© 1998 MXxCOM Inc. www.mxcom.com Tele: 800 638-5577 910 744-5050 Fax: [phone] Doc. # 20480115.003

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Dual SPM Detector 7 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

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

DD

.

µController

Ch 2

I/O Ports

Ch 1

XTAL/CLOCK

X1

3 to'N' LINE

DECODER

"OUTPUT ENABLE"

ADDRESSING

XTAL

CLOCK

OUT

MX641

(used as

Master

Oscillator)

Ch 1

CLOCK

IN

Ch 2

CLOCK

IN

XTAL/CLOCK

MX641 MX641 MX641

Ch 1

V

DD

XTAL/CLOCK

Ch 2

CLOCK

IN

Ch 1

XTAL/CLOCK

Ch 2

OUTPUT

ENABLE

CLOCK

IN

Ch 1 OUTPUT

Ch 2 OUTPUT

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

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Dual SPM Detector 8 MX641 PRELIMINARY INFORMATION

SIGNAL INPUT

CH1 and CH 2 OUTPUTS

TONE FOLLOWER OUTPUT

PACKET MODE OUTPUT

SIGNAL INPUT ......

TONE F O L L OWER OUTPUT ......

PACKE T MODE OUTPUT ......

Figure 4: Tone Follower and Packet Mode Outputs

TONE NOTONE

RESPONSE

DELA Y

DERESPONSE

DELA Y

4.3 Sensitivity Setting

To enable the MX641 to operate correctly to most national 12kHz and 16kHz SPM specifications, the input sensitivity can
be accurately adjusted and set.

There are two different pin-selectable modes of sensitivity setting available to the MX641: Controlled Sensitivity Mode and
Fixed Sensitivity Mode

The Controlled Sensitivity mode allows the sensitivity setting from a µController via a 6-bit serial data input. This same
serial input also sets operation (bit 0) to either 12kHz or 16kHz systems. Both channels are set identically.

The Fixed Sensitivity mode allows the sensitivity of each channel to be set to a fixed “gain” by external components at the
input amplifiers. Operation to either 12kHz or 16kHz is by the System Select input.

4.3.1 Controlled Sensitivity Setting

With the external gain (sensitivity) components used as shown in Figure 2, the gain of the input stages is 19.8dB (12kHz)
or 20.5dB (16kHz). For controlled sensitivity setting the gain of each bandpass filter, and therefore the device sensitivity,
is adjusted by the applied serial bits D1 to D5.

In the Controlled Sensitivity mode the system frequency is selected by bit D0 (‘1’ = 12kHz; ‘0’ = 16kHz). Data is loaded
Bit 5 (D5) first. Table 4 details the serial data inputs for the required sensitivity. Minimum, Nominal and Maximum
Sensitivity figures are provided to make complete allowance for internal circuit offsets and component tolerances.
0dB(ref.) = 775mV

Note: Device sensitivity is directly proportional to V

at VDD = 5.0 volts; varies directly with VDD.

RMS

DD

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Dual SPM Detector 9 MX641 PRELIMINARY INFORMATION

4.3.1.1 Controlled Sensitivity Setting Information

The sensitivity figures in Table 4 are based on the following:

1. The recommended amplifier components (see Figure 2) are used, providing an amplifier gain at 16kHz
of 19.8dB ±0.3dB or at 12kHz of 19.1dB ±0.3dB.

2. A comparator sensitivity of 1.6dB(ref.) ±1dB (the variation is due to filter gain error, filter output offset, comparator
input offset or a combination of all 3).

3. The applied V

is 5.0 volts; 0dB (ref.) = 775mV

DD

RMS

.

Serial Data

Bits

Bandpass

Filter Gain

Minimum

Sensitivity

12kHz System

Bit D0 = ‘1’

Nominal

Sensitivity

Maximum

Sensitivity

Minimum

Sensitivity

16kHz System

Bit D0 = ‘0’

Nominal

Sensitivity

Maximum

Sensitivity

D5 - D1 (dB) dB(ref.) dB(ref.) dB(ref.) dB(ref.) dB(ref.) dB(ref.)

00000 0 -16.2 -17.5 -18.8 -16.9 -18.2 -19.5
00001 1.0 -17.2 -18.5 -19.8 -17.9 -19.2 -20.5
00010 2.0 -18.2 -19.5 -20.8 -18.9 -20.2 -21.5
00011 3.0 -19.2 -20.5 -21.8 -19.9 -21.2 -22.5
00100 4.0 -20.2 -21.5 -22.8 -20.9 -22.2 -23.5
00101 5.0 -21.2 -22.5 -23.8 -21.9 -23.2 -24.5
00110 6.0 -22.2 -23.5 -24.8 -22.9 -24.2 -25.5
00111 7.0 -23.2 -24.5 -25.8 -23.9 -25.2 -26.5
01000 8.0 -24.2 -25.5 -26.8 -24.9 -26.2 -27.5
01001 9.0 -25.2 -26.5 -27.8 -25.9 -27.2 -28.5
01010 10.0 -26.2 -27.5 -28.8 -26.9 -28.2 -29.5
01011 11.0 -27.2 -28.5 -29.8 -27.9 -29.2 -30.5
01100 12.0 -28.2 -29.5 -30.8 -28.9 -30.2 -31.5
01101 13.0 -29.2 -30.5 -31.8 -29.9 -31.2 -32.5
01110 14.0 -30.2 -31.5 -32.8 -30.9 -32.2 -33.5
01111 15.0 -31.2 -32.5 -33.8 -31.9 -33.2 -34.5
10000 16.0 -32.2 -33.5 -34.8 -32.9 -34.2 -35.5
10001 17.0 -33.2 -34.5 -35.8 -33.9 -35.2 -36.5
10010 18.0 -34.2 -35.5 -36.8 -34.9 -36.2 -37.5
10011 19.0 -35.2 -36.5 -37.8 -35.9 -37.2 -38.5
10100 20.0 -36.2 -37.5 -38.8 -36.9 -38.2 -39.5
10101 21.0 -37.2 -38.5 -39.8 -37.9 -39.2 -40.5
10110 22.0 -38.2 -39.5 -40.8 -38.9 -40.2 -41.5
10111 23.0 -39.2 -40.5 -41.8 -39.9 -41.2 -42.5
11000 24.0 -40.2 -41.5 -42.8 -40.9 -42.2 -43.5
11001 25.0 -41.2 -42.5 -43.8 -41.9 -43.2 -44.5
11010 26.0 -42.2 -43.5 -44.8 -42.9 -44.2 -45.5
11011 27.0 -43.2 -44.5 -45.8 -43.9 -45.2 -46.5
11100
11101
11110

These states should never be used. If sensitivities of this order are required (e.g. the Swedish
Rural SPM specification), it is recommended that the Controlled Sensitivity setting be set to 20dB
(10100) and external components selected to set the Input Amp gain to a higher figure. This
action will prevent falsing by sub-harmonic frequencies.

11111

Table 4: Controlled Sensitivity Setting Information

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Dual SPM Detector 10 MX641 PRELIMINARY INFORMATION

4.3.1.2 German FTZ Specification (16kHz)

The FTZ system has a Must Decode level of -21dB (ref.) and a Must-Not Decode level of -27dB (ref.). Reference to
Table 4 shows that Bandpass Filter Gain settings of 5dB, 6dB or 7dB will enable an MX641 channel to meet this level
specification. Figure 5 illustrates the range of these various settings.

To meet the German FTZ specification, the input data (D5 to D0) must be:

0 0 1 0 1 0 5.0dB
or 0 0 1 1 0 0 6.0dB
or 0 0 1 1 1 0 7.0dB

Note:

1. By selecting the middle setting, the greatest noise immunity is achieved.

MUST DECODE

-21.9

-23.2 5.0dB

-24.5

MUST -NO T DECODE

WILL DECODE

-22.9

-24.2 6.0dB

-25.5

WILL-NOT DECODE

-21dB(ref.)

-23.9

-25.2 7.0dB

-26.5

-27dB(ref.)

Figure 5: German Specification - Possible Settings

4.3.1.3 French Specification (12kHz)

This system has a Must Decode level of -17.36dB (ref.) and a Must-Not Decode level of -23.8dB (ref.). Reference to
Table 4 shows that Bandpass Filter Gain settings of 2dB, 3dB or 4dB will enable an MX641 channel to meet this level
specification. Figure 6 illustrates the range of these various settings.

To meet the French SPM specification, the input data (D5 to D0) must be:

0 0 0 1 0 1 2.0dB

or 0 0 0 1 1 1 3.0dB
or 0 0 1 0 0 1 4.0dB

Note:

1. By selecting the middle setting, the greatest noise immunity is achieved.

MUST DECODE

-18.2

-19.5 2.0dB

-20.8

WILL-NOT DECODE

MUST -NO T DECODE

WILL DECODE

-19.2

-20.5 3.0dB

-21.8

-17.36dB(ref.)

-20.2

-21.5 4.0dB

-22.8

-23.8dB(ref.)

Figure 6: French Specifications - Possible Settings

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Dual SPM Detector 11 MX641 PRELIMINARY INFORMATION

4.3.2 Fixed Sensitivity Setting

In this mode the sensitivity of each channel is set by the correct selection of the components around the Channel Input
Amplifier. Note that the device sensitivity is directly proportional to the applied power supply (V

bandwidth product of the input opamp can attenuate the SPM signal gain at some input gain configurations.

4.3.2.1 Input Gain Calculation

The input amplifier, with external circuitry, is used to set the sensitivity of the MX641 to conform to the user's national level
specification with regard to ‘Must’ and ‘Must-Not’ decode signal levels.

With reference to the graph in Figure 7, the following steps will assist in the determination of the required gain/attenuation.

Step 1 Draw two horizontal lines from the Y-axis (Signal Level) in Figure 7. The upper line represents the required

‘Must’ decode level. The lower line represents the required ‘Must-Not’ decode level

Step 2 Mark the intersection of the upper horizontal line and the upper sloping line; drop a vertical line from this point to

the X-axis (Amplifier Gain (dB)). The point where the vertical line meets the X-axis indicates the minimum Input
Amp gain required for reliable decoding of valid signals

Step 3 Mark the intersection of the lower horizontal line and the lower sloping line; drop a vertical line from this point to

the X-axis. The point where the vertical line meets the X-axis will indicate the maximum allowable Input Amp
gain. Input signals at or below the ‘Must-Not’ decode level will not be detected as long as the amplifier gain is
no higher than this level.

-10

) and that the gain

DD

-15

RMS

-20

MUST DECODE LEVEL

-25

-30

-35

-40

SIGNAL LEVEL (dB): 0dB ref = 775mV

-45

-50

MUST-NOT DECODE LEVEL

MINIMUM AMPLIFIER GAIN

-20 -15 -10

MAXIMUM AMPLIFIER GAIN

-5

V = 5.0 (±0.1) VOLTS; TEMP = -40°C to 85°C

DD

0

AMPLIFIER GAIN (dB)

5

10 15 20 25

Figure 7: Input Gain Calculation Graph for use in the Fixed Sensitivity Mode

4.3.2.2 Input Gain Components

Refer to the gain components shown in Figure 2. The user should calculate and select external components (R1/R3/C3,
R2/R4/C4 and R5/R7/C5, R6/R8/C6) to provide amplifier gains within the limits obtained in Steps 2 and 3.

Component tolerances should not move the gain-figure outside these limits. The graph in Figure 7 is for the calculation of
input gain components for an MX641 using a V

of 5.0 (±0.1) volts.

DD

It is recommended that the designed gain is near the center of the calculated range.

© 1998 MXxCOM Inc. www.mxcom.com Tele: 800 638-5577 910 744-5050 Fax: [phone] Doc. # 20480115.003

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Dual SPM Detector 12 MX641 PRELIMINARY INFORMATION

5. Applications

5.1.1 Input Configurations

Tip (a)

Ring (b)

Differential Input

INPUT AMP

­+

V

BIAS

MX641

Common Mode Input

INPUT AMP

­+

MX641

V

BIAS

Figure 8: Input Configurations

5.1.2 Protection Against High Voltages

Telephone systems may have high d.c. and a.c. voltages present on the line. If the MX641 is part of a host equipment
that has its own signal input protection circuitry, there will be no need for further protection as long as the voltage on any
pin is limited to within V

If the host system does not have input protection, or there are signals present outside the device's specified limits, the
MX641 will require protection diodes at its signal inputs (+ and -). The breakdown voltage of capacitors and the peak
inverse voltage of the diodes must be sufficient to withstand the sum of the d.c. voltages plus all expected signal peaks.

+0.3V and VSS -0.3V.

DD

5.1.3 Aliasing

Due to the sampling nature of switched-capacitor filters used in the MX641, high frequency noise or unwanted signals can
alias into the passband, disrupting detection. External components must be chosen carefully to avoid alias effects.

Possible Alias Frequencies:

12kHz Mode = 52kHz
16kHz Mode = 69kHz

If other filtering in the system has not attenuated these alias frequencies, capacitors should be employed across resistors
R3, R4, R7 and R8 to provide anti-alias filtering.

The low-pass cutoff frequency should be chosen to be approximately 20kHz to 25kHz for a 12kHz system, or 25kHz to
30kHz for a 16kHz system.

i.e.

C

2S

When anti-alias capacitors are used, an allowance must be made for reduced gain at the SPM frequency (12kHz or
16kHz).

1

f

uu u

2

R3

© 1998 MXxCOM Inc. www.mxcom.com Tele: 800 638-5577 910 744-5050 Fax: [phone] Doc. # 20480115.003

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Dual SPM Detector 13 MX641 PRELIMINARY INFORMATION

6. Performance Specification

6.1 Electrical Specifications

6.1.1 Absolute Maximum Ratings

Exceeding the maximum rating can result in device damage.

Parameter Min. Typ. Max. Unit

Supply Voltage (VDD-VSS) -0.3 7.0 V
Voltage on any pin to V

SS

Current

V

DD

V

SS

Any other pin -20 20 mA

DW / P Packages

Total allowable device dissipation at T

Derating above T

AMB

25qC

AMB

25

qC

Operating Temperature -40 85
Storage Temperature -40 85

-0.3 (VDD + 0.3) V

-30 30 mA

-30 30 mA

800 mW

10

mW/qC above T

qC
qC

AMB

25qC

6.1.2 Operating Limits

Correct Operation of the device outside these limits is not implied.

Parameter Min. Typ. Max. Unit

Supply Voltage (VDD) 4.5 5.0 5.5 V
Operating Temperature -40 85

Xtal/Clock Frequency 3.558918 3.589368 MHz

6.1.3 Operating Characteristics

All device characteristics are measured under the following conditions unless otherwise specified:
V

= 5.0V @ T

DD

Audio Level 0dB (ref.) = 775mV
Xtal/Clock Frequency = 3.579545MHz, System Setting = 12kHz or 16kHz

Supply Current 2.0 5.0 mA

Input/Output Parameters

Clock Out Load 17 15.0 pF

Logic Inputs

Input Logic ‘1’ (High) 3.5 V
Input Logic ‘0’ (Low) 1.5 V
Input Leakage Current (VIN = 0 to VDD)13-5.05.0

Input Current (VIN = 0) 14 -15.0

AMB

= 25qC

, Noise Bandwidth = 50kHz

RMS

Notes Min. Typ. Max. Units

PA
PA

© 1998 MXxCOM Inc. www.mxcom.com Tele: 800 638-5577 910 744-5050 Fax: [phone] Doc. # 20480115.003

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Dual SPM Detector 14 MX641 PRELIMINARY INFORMATION

Notes Min. Typ. Max. Units

Channel Outputs

Output Logic ‘1’ IOH = 120mA (Enabled) 1 4.6 V
Output Logic ‘0’ IOL = 360mA (Enabled) 1 0.4 V
Output Leakage Current High-Z Output 2 -5.0 5.0

A

P

Input Amplifier

D. C. Gain 60.0 dB
Bandwidth (-3dB) 100 Hz
Input Impedance 1.0

M

:

Overall Performance

12kHz Detect Bandwidth 3 11.82 12.18 kHz
12kHz Not-detect Frequencies (Below 12kHz) 3 11.52 kHz
12kHz Not-detect Frequencies (Above 12kHz) 3 12.48 kHz
16kHz Detect Bandwidth 3 15.76 16.24
16kHz Upper Decode Band Edge (Below 16kHz) 3 15.36 kHz
16kHz Lower Decode Band Edge (Above 16kHz) 3 16.64 kHz
Level Sensitivity

Controlled Sensitivity Mode 3,4,12,15 2.6 1.6 0.6 dB(ref.)
Preset Sensitivity Mode 3,4,5,16 -25.4 -26.4 -27.4 dB(ref.)

Signal Quality Requirements

Signal-to-Noise (Amp Input) 4,8,9,10 22.0 20.0 dB
Signal-to-Voice (Amp Input) 4,8,9,11 -36.0 -40.0 dB
Signal-to-Voice (Amp Output) 4,8,10,11 -1.0 -27.0 dB
Channel Outputs (Ch1 and Ch2) Figure 4

Mode Change Time 6 500 ns

Tone Follower Mode (Table 3)

Response and De-Response Time 3, 4, 7 10.0 ms

Packet Mode (Table 3)

Response and De-Response Time 3, 4, 7 40.0 48.0 ms

Note:

1. Tone Follower or Packet mode enabled; see Table 3

2. Tristate selected; see Table 3.

3. With adherence to Signal-to-Voice and Signal-to Noise specifications.

4. 12kHz and/or 16kHz system.

5. With Input Amp gain setting = 0dB.

6. Time taken to change between any two of the operational modes: Tone Follower, Packet or Tristate, and with a
maximum capacitive load of 30pF on an output.

7. The time delay, after a valid serial data load (or after device powerup), before the condition of the outputs can be
guaranteed correct.

8. Immunity to false responses and/or de-responses.

9. Common Mode SPM and balanced voice input signal.

10. With SPM and voice signal amplitudes balanced; to avoid false de-responses due to saturation, the peak-to-peak
voice + noise level at the output of the Input Amp should be no greater than the dynamic range of the device. For
this reason, the signal-to-voice figure at the AMP Output will vary with the sensitivity setting. The lowest
signal-to-voice figure occurs at the highest sensitivity setting. (Table 4 27dB)

© 1998 MXxCOM Inc. www.mxcom.com Tele: 800 638-5577 910 744-5050 Fax: [phone] Doc. # 20480115.003

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Dual SPM Detector 15 MX641 PRELIMINARY INFORMATION

11. Maximum voice frequencies = 3.4kHz.

12. With the Input Amplifier gain at 0dB and the Bandpass Filter gain set at 0dB (Table 4); subtract 1.0dB from this
specification for each extra single dB of Bandpass Filter gain programmed.
Alternatively, with the input components as recommended in Figure 2, the sensitivity is as defined in Table 4.

13. Logic inputs with no internal pullup; Chip Select, Serial Data, Serial Clock, Output Enable, Output Select and Clock
In pins.

14. Logic inputs with an internal pullup; Preset Level and System Select pins.

15. Preset Level = ‘0’, System Select = don't care; Chip Select, Serial Clock and Serial Data inputs active;
see Table 3.

16. Preset Level = ‘1’, System Select = input active; Chip Select, Serial Clock and Serial Data inputs inactive;
see Table 3

17. Maximum Clock Output Fan out = 4 (including master)

6.2 Timing

Parameter Min. Typ. Max. Unit

t

PWH

t

PWL

t

CYC

t

CSE

t

DH

t

DS

Serial Clock ‘High‘ Pulse Width 250 ns
Serial Clock ‘Low’ Pulse Width 250 ns
Serial Clock Period 600 ns
Chip Select ‘Low’ to Clock ‘High’ Edge 450 ns
Data Hold Time 50.0 ns
Data Setup Time 250 ns

CHIP SELECT

SERIAL CLOCK

SERIAL DATA

t

CSE

t

CYC

t

PWH

D3

BIT D0

Don't
Care
Data

t

PWL

t

DS

t

DH

BIT D5 BIT D4

Figure 9: Data Load Timing for the Controlled Sensitivity Mode

t

CSH

© 1998 MXxCOM Inc. www.mxcom.com Tele: 800 638-5577 910 744-5050 Fax: [phone] Doc. # 20480115.003

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Dual SPM Detector 16 MX641 PRELIMINARY INFORMATION

6.3 Packages

Packa geTolerances

Alternative Pin

Location

Marking

PIN 1

Y

H

A

B

E

W

T

X

Z

A

0.597 (15.16)

B

0.286 (7.26)

0.093 (2.36)

C

0.390 (9.90)

E
H

0.013 (0.33)

L

J

K
L

P
T

0.036 (0.91)

0.016 (0.41)

0.009 (0.23)

W

K

C

X
Y

J

P

Z

NOTE: All dimensions in inches (mm.)

0°
5°

Angles are in degrees

Figure 10: 24-pin SOIC Mechanical Outline: order as part no. MX641DW

AA

Packa geTolerances

TYP. MAX.MIN.DIM.

0.613 (15.57)

0.299 (7.59)

0.105 (2.67)

0.419 (10.64)

0.020 (0.51)0.003 (0.08)

0.020 (0.51)

0.046 (1.17)

0.050 (1.27)

0.050 (1.27)

0.0125 (0.32)

45°

10°

7°

5°

PIN1PIN1

K

H

L

BB

E1E1

EE

Y

A
B
C
E

E1

TT

H
J

J1

K

CC

L
P
T
Y

PP

JJ

J1J1

NOTE: All dimensions in inches (mm.)

Figure 11: 24-pin PDIP Mechanical Outline: order as part no. MX641P

TYP. MAX.MIN.DIM.

1.200 (30.48)

0.500 (12.70)

0.151 (3.84)

0.600 (15.24)

0.590 (14.99) 0.625 (15.88)

0.015 (0.38) 0.045 (1.14)

0.015 (0.38) 0.023 (0.58)

0.040 (1.02) 0.065 (1.65)

0.066 (1.67) 0.074 (1.88)

0.121 (3.07)

0.100 (2.54)

0.008 (0.20) 0.015 (0.38)

Angles are in degrees

1.270 (32.26)

0.555 (14.04)

0.220 (5.59)

0.670 (17.02)

0.160 (4.05)

7°

© 1998 MXxCOM Inc. www.mxcom.com Tele: 800 638-5577 910 744-5050 Fax: [phone] Doc. # 20480115.003

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.