ST75C540 datasheet(19/84 Pages) STMICROELECTRONICS

19 / 84 page

V.4.3 - Crystal

The crystal frequency must be 44.2368MHz for

ST75C530 and 49.152MHz for ST75C540 with an

accuracy better that

±100 ppm. When using a third

harmonic crystal the schematic must be as follow :

see Figure 10.

The crystal features are :

- third harmonic,

- parallel, load capacitance = 10pF,

- æ 100ppm from 0

oCto 70oC,

-RS <50

Ω,

- ATcut (example : SM55-10 MATEL).

XTAL H3 **

27pF

COG

0.82

µH (ST75C530)

0.68

µH (ST75C540)

10nF

10pF

COG

ST75C540

EXTALL

XTALL

Wire wound inductor recommanded (Example : SIGMA-SC30)

Thrird harmonic (Example : MATEL-SM55-10)

XTAL H3 : 44.2368MHz (ST75C530)

49.152MHz (ST75C540)

Figure 10

V.4.4 - Typical Application Schematic

The Figure 11 is a block diagram designed to allow

transmission of fax signals up to +0dBm and sine

wave up to +6dBm on the telephone line. It allows

reception of fax signals up to 0dBm and sine waves

up to +6dBm.Figure12 is a blockdiagramdesigned

V - FUNCTIONAL DESCRIPTION (continued)

-1/2

600

Ω

1:1

Line

2.2nF

+8dB

-10dB

TxA1

TxA2

RxA

Figure 11

-1/2

600

Ω

1:1

Line

2.2nF

0dB

TxA1

TxA2

RxA

Figure 12

to allow transmission of Modem signal up to -

10dBm and reception up to -10dBm. The OPAmps

are +12/0V powered. With this application sche-

matic the out of band transmit spectrum (from 4kHz

to 50kHz) is below -72dBm.

Figures 13 and 14 are examples of application sche-

maticswhich respectsgainvalue(respectivelyfor fax

and voice application and for Modem application)

andthe minimum differentialloadon TxA1 andTxA2.

V.4.5 - Host Interface

The host interface is seen by the micro as a 128x8

RAM, with additional registers accessible through

an 8-bit address space. A selection Pin (INT/MOT)

allows to configurethe host bus for either INTEL or

MOTOROLA type control signals.

ST75C530 - ST75C540

19/84

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