MC145574 Datasheet, PDF (119/164 Pages) Motorola, Inc – ISDN S/T-Interface Transceiver

Freescale Semiconductor, Inc.
16.4 ADDITIONAL NOTES
16.4.1
Sources of Line Interface Transformers
Line interface transformers for use with the MC145574 S/T may be obtained from the following
manufacturers:
Pulse Engineering
P.O. Box 12235
San Diego, California 92112
Tel : 619–674–8100
Fax : 619–674–8262
Part # PE 64998 (single)
Part # PE 65498 (dual)
Secre Composants
117, rue de Cambrai
75019 Paris, France
Tel : (331) 44–89–48–00
Fax : (331) 42–05–15–19
Part # E01170, E01167
Part # E01171 (SMD)
FEE S.A.
Zone Industrielle
39270 Orgelet
France
Tel: (33) 84–35–04–04
Fax: (33) 84–25–46–41
Part # FE2150
APC
47 Riverside, Medway City Estate
Strood, Rochester, Kent ME2 4DP
United Kingdom
Tel: (44) 1634–290–588
Fax: (44) 1634–290–591
Part # APC15103
Motorola cannot recommend one manufacturer over another and in no way implies that this is a com-
plete listing.
16.4.2
Termination Resistors
Note that the 100 Ω termination resistors in the transmit and receive line circuitry (as shown in Fig-
ures 16–1 and 16–2) are mandatory when operating as an NT in accordance with CCITT I.430, ETSI
ETS 300012, and ANSI T1.605. When operating as a TE in point–to–point mode, these are also re-
quired. However, when configured as a TE in the passive bus arrangement, only one TE has these
termination resistors. The 100 Ω termination resistor should also be removed for some conformance
tests.
16.4.3
Protection Diodes
CCITT I.430, ETSI ETS 300012, and ANSI T1.605 specify that the S/T–interface voltage cannot exceed
1.6 times the nominal voltage of 750 mV (= 1.2 V). Since the MC145574 is designed to operate with
2.5:1 turns ratio transformers, the diode structure as illustrated in Figures 16–1 and 16–2 is required
to provide protection, while not adversely affecting the S/T–interface when power is removed from
the device. This diode structure also protects the circuit against electrostatic discharges (ESD) and
latch–up.
CAUTION
The four pins RxP, RxN, TxP, and TxN are not internally protected against ESD and caution
must be taken during handling and mounting the devices to prevent any possible electrical
overstress.
MOTOROLA
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16–3