MC145572PB Freescale Semiconductor, MC145572PB Datasheet - Page 222

• Manufacturer Part Number: MC145572PB
• Manufacturer: Freescale Semiconductor

Specifications of MC145572PB

• Number Of Line Interfaces: 1
• Control Interface: HDLC
• Lead Free Status / Rohs Status: Not Compliant

E–2
The impedance looking into the secondary side of the transformer must equal R L / (N 2 ) in order to
terminate the line.
Rearranging and solving for R x gives:
Substituting in values,
for a prototype transformer: R p = 7.9
we get:
R x = 5000 * (135 – 7.9 * 1.25 2 – 8.2 – 2 * 5 + j4) / (– j4 + 8.2 + 7.9 * 1.25 2 + 2 * 5000 * 1.25 2
Since the reactive component is so small, having an angle of only 2.20 , it can be ignored when doing
this analysis.
= 5000 * (104.5 + j4) / (15520.5 – j4)
= 5000 * 104.6 < 2.19 / (15520.5 < – 0.01 )
= 33.7
V g
V g
+
-
+
-
R g = 0.05
R g = 0.05
+ 2 * 5 – 135)
R x = R i * (R L – N 2 * R p – 2 * R TP – R s – X c ) / (X c + R s + N 2 * R p + 2 * N 2 * R i + 2 * R TP – R L )
< 2.20
Freescale Semiconductor, Inc.
(2R x * 2R i ) / (2R i + 2R x ) + R p + (R s + X c + 2 * R TP ) / (N 2 ) = R L / (N 2 )
R f
For More Information On This Product,
R i
R f
X c = 1 / (j * 2 * PI * 40000 * 1E – 06) = – j4
R x P
R x N
T x N
T x N
Go to: www.freescale.com
Figure E–2. Transmit Circuit Model
R i
R i
Figure E–3. Transformer Model
R x
T x N
T x P
MC145572
R x P
R x N
and R s = 8.2
R x
R x
R i = 5000
C1
R TP = 5
C1
R p
R p
R s /N 2
1:N
at 40 kHz
2R TP /N 2
R s
R TP
C b
X c /N 2
R TP
MOTOROLA
T
R
T
R
R L /N 2
R L
(1)
(2)