MC145574 Datasheet, PDF (63/164 Pages) Motorola, Inc – ISDN S/T-Interface Transceiver

Freescale Semiconductor, Inc.
7
PIN DESCRIPTIONS
7.1 INTRODUCTION
The Motorola MC145574 ISDN S/T transceiver is available in a 28–pin SOIC and a 32–pin TQFP
package (see Figure 7–1).
28–LEAD SOIC
32–LEAD TQFP
ISET 1
RxN 2
RxP 3
TE/NT 4
M/S 5
T_IN/TFSC/TCLK/FIX 6
VSS 7
SG/DGRANT/ANDOUT 8
DREQUEST/ANDIN 9
CLASS/ECHO_IN 10
FSC/FSR 11
DCL 12
Din 13
Dout 14
28 RESET
27 TxP
26 TxN
25 XTAL
24 EXTAL
23 VDD5
22 VDD I/O
21 VDD3
20 IRQ/IND
TE/NT
M/S
T_IN/TSFC/TCLK/FIX
VSS
SG/DGRANT/ANDOUT
DREQUEST/ANDIN
CLASS/ECHO_IN
FSC/FSR
32 31 30 29 28 27 26 25
1
24
2
23
3
22
4
21
5
20
6
19
7
18
8
17
9 10 11 12 13 14 15 16
XTAL
EXTAL
VDD5
VDD I/O
VDD3
IRQ/IND
TSEN/FSX/BCL/LBA
SCPEN/GCIEN
19 TSEN/FST/BCL/LBA
18 SCPEN/GCIEN
17 SCPCLK/S2/M2
16 SCPRx/S1/M1
15 SCPTx/S0/M0
Figure 7–1. Pin Assignments
7.2 PIN DESCRIPTIONS
The following pin descriptions are not intended to be exhaustive but merely indicate the operational
modes of the pins. For complete operational details please refer to the appropriate sections of this
document.
7.2.1
ISET
In both the NT and TE modes of operation, a current programming reference resistor of value
30 kΩ accurate to 5% should be connected between this pin and VSS. This resistor provides biasing
and programs the current limit for the TxP and TxN driver circuit. Note that this resistor is not user
programmable and must be 30 kΩ for CCITT 1.430, ETSI ETS 300012, and ANSI T1.605 compatibility.
7.2.2
RxN, RxP
These two pins form the differential receiver for the S/T–interface. They are connected to the S/T
loop via a transformer. For further information, refer to Section 16.
MOTOROLA
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7–1
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