am79c30a Advanced Micro Devices, am79c30a Datasheet - Page 79

• Manufacturer Part Number: am79c30a
• Description: Digital Subscriber Controller ?dsc ?circuit
• Manufacturer: Advanced Micro Devices

Series Resistor Calculations
Equation 1
Equation 2
Equation 3
Let R
Equation 4
Notes:
N = 2
R
V
I
Equation 5
Equation 5 should be used to determine the value of R
I
R
R
R
LOUT
LOUT
Notes:
1. R
2. R
3. R
4. N is the transformer turns ratio (N = 2 for Am79C30A/32A).
5. R
6. I
7. V
LOUT
L
1
1
1
+
+
= 50 ohms
=
LOUT
R
R
1
LOUT
SEC
PRIM
CORD
L
R
= 7.5 mA
2
2
=
= R
= 2.326 V
is the S-interface line impedance (50 ohms).
2
=
=
--------------------------------------------------------------------------------------------------------------------------------------------------------------
R
=
is the DC impedance of the transformer secondary (IC side of transformer).
is the desired load current for the CCITT transmission templates (7.5 mA for 50-ohm line).
1
is the DC impedance of the transformer primary (line side of transformer).
--------------------- - R
1
-- -
2
is the nominal output voltage from the DSC/IDC line driver.
2
is the DC impedance of the TE connecting cord; typically 4–6 ohms.
V
55.067
+
I
LOUT
LOU T
V
---------------- - R
R
I
LOUT
LOUT
2
LOUT2
LOUT1
+
Figure 28. Equivalent DC Circuit at LOUT Pins for Calculation of R
R
+
–
SEC
–
1
-- - R
2
SEC
SEC
+
SEC
–
+
–
R
–
I
LOUT
PRIM
+
R
R
PRI M
V
4 R
PRIM
LOUT
V
N
LOU T
PRI M
2
N
N
2
+
2
R
R
–
R
2
1
–
+
L
R
Am79C30A/32A Data Sheet
R
4 R
L
L
N
2
N
N
COR D
2
+
2
R
–
R
SEC
–
CORD
R
1
R
CORD
and R
COR D
R
PRIM
N
2
2
N
for the particular transformer used by each customer.
N
2
2
• N
2
R
CORD
• N
2
R
L
• N
1
2
and R
2
09893H-20
79