MT8930C-1 Datasheet, PDF (28/42 Pages) Mitel Networks Corporation – CMOS ST-BUS™ FAMILY Subscriber Network Interface Circuit

MT8930C
MT8930C
AD0-AD7
CS
DS
R/W
AS
V_DD
74HCT245
DIR
BA
G
74HCT245
AB
DIR
G
QD
MC6802
(MC6809)
A0 - A7
Address
Decoder _VDD
VMA
D0 - D7
R/W
E
EXTAL (Q)
Connections to interface to MC6809
Figure 19 - Interfacing to the MC6802 Microprocessor
ETS 300-012 NT&TE Line Interface
Figures 20, 21 and 22 show the recommended line
interface circuits for meeting the ETS 300-012
requirements. These circuits assume that test
measurements are made using the "standard
reference cord" which has the following
specifications:
C = 315pF to 350pF
R = 2.7Ω to 3.0Ω
Z > 75Ω
Length < 10m
Several types of transformers can be used:
• Filtran TPW-3852-4 (Figure 20)
• VAC T60403-L4096-X028 (Breakdown Voltage
4KV) (Figure 21)
• VAC T60403-L4096-X027 Breakdown Voltage
2KV) (Figure 21)
• VAC T60403-L4096-X029 (Breakdown Voltage
4KV) (Figure 22)
• VAC T60403-L4096-X030 (Breakdown Voltage
2KV) (Figure 22)
L4096-X029 and L4096-X030 are equivalent to
L4096-X028 and L4096-X027 with the exceptions of
pin out; L4096-X029 and L4096-X030 are pin
compatible with L4096-X028-80.
In Figure 20, T1, 2 (Filtran TPW-3852-4) provides
isolation, longitudinal balance, impedance matching
and voltage level conversion. D5 and 6 (germanium)
ensure that the pulse shape lies within the center of
the various pulse templates. D1-4 protect the
MT8930C from line transients. C2, 3 decouple the
VBias voltage and optimize the receiver sensitivity.
R1 and C4 make up a low-pass filter recommended
for delaying the signal in TE applications, this filter
can also be used for NT applications allowing
common hardware for TE and NT applications. K1
isolates the MT8930C from the line for multidrop
applications in cases where the device is powered
down. L1 is 4-winding 5mH common mode choke to
suppress EMI on the 4-wire line.
The TPW-3852-4 is available from:
Filtran Ltd.
229 Colonnade Road
Nepean, Ontario
Canada
Telephone: [phone]
9-60