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MH8843AS

Calling Number Identification Circuit 2

Mitel Networks 

Preliminary Information

MT8843

The crystal specification is as follows:

Applications

Frequency:

3.579545 MHz

Frequency tolerance:

±0.1%(-40°C+85°C)

Resonance mode:

Parallel

Load capacitance:

18 pF

Maximum series resistance: 150 ohms

Maximum drive level (mW): 2 mW

e.g., CTS MP036S

Any number of MT8843 devices can be connected

as shown in Figure 8 such that only one crystal is

required. The connection between OSC2 and OSC1

can be D.C. coupled as shown, or the OSC1 inputs

on all devices can be driven from a CMOS buffer (dc

coupled) with the OSC2 outputs left unconnected.

VRef and CAP Inputs

The circuit shown in Figure 9 illustrates the use of the

MT8843 (CNIC2) device in a typical CID or CLIP sys-

tem. Network protection will differ depending on the

market for which the product is designed.

Notes:

CNIC2 has not been fully characterized for talkoff

and talkdown performance as specified in SR-TSV-

002476.

For CIDCW, speech immunity improves if near end

audio is cancelled from the incoming signal. One

possible implementation is to connect the signal

input to the 2 wire side when the CPE is on-hook and

the 4 wire side when the CPE is off-hook.

VRef is the output of a low impedance voltage source

equal to VDD/2 and is used to bias the input op-amp.

A 0.1µF capacitor is required between CAP and VSS

to suppress noise on VRef.

TIP / A

Notes

RING / B

For BT network

protection:

TISP4180,

TISP5180,

TPA150A12 or

TPB150B12

0.01µF

0.01µF

+5V

430K

34K

+5V

430K

34K

+5V

500K

0.1µF

R

500K

0.1µF

200K

C

300K

+5V

464K

MT8843

CNIC2

IN+

IN-

GS

VRef

CAP

TRIGin

TRIGRC

TRIGout

MODE

OSCin

OSCout

VSS

VDD

St/GT

ESt

StD

INT

CD

DR

DATA

DCLK

FSKen

PWDN

IC

420K

420K

+5V

100K

Note: For CTA applications where there is a requirement to determine

the ring burst duration, the value of R and C may have to be optimized.

Figure 9 - Application Circuit

= To microcontroller

= From microcontroller

(FSK Interface Mode 0 selected)

5-29

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