73M1903C-EVM Maxim Integrated Products, 73M1903C-EVM Datasheet - Page 41

• Manufacturer Part Number: 73M1903C-EVM
• Description: BOARD DEMO 73M1903C WORLDWIDE
• Manufacturer: Maxim Integrated Products

Specifications of 73M1903C-EVM

• Main Purpose: Interface, Analog Front End (AFE)
• Utilized Ic / Part: *
• Primary Attributes: *
• Secondary Attributes: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Embedded: -

DS_1903C_033
When both drivers are used for worldwide applications, the recommended connections are shown below.
The termination realized when the primary driver is selected is 2R1 + Rwtot;
With the secondary driver is selected it is 2Z4 + Rwtot.
Still keep R2 + R3 = 100K.
and
The R3 resistors will be much larger than for the case when only a single transmitter is used since the
impedance needed to cancel the transmit signal in the receiver is now supplied by two R3 resistors in
parallel instead of only one. This means the resistors will be approximately twice the ratio values in the
previous case.
Trans-Hybrid Loss (THL)
Trans-Hybrid Loss is by definition the loss of transmit signal from Tip/Ring to the receive inputs on the
modem IC. This definition is only valid when driving a specific phone line impedance. In reality, phone
line impedances are never perfect, so this definition isn’t much help. Instead, as an alternate definition
that helps in analysis for this modem design, THL is the loss from the transmit pins to the receive pins.
Rev. 5.0
R2 100 K
R3
1
+
Rwtot
R3 .
Rwtot
100K
+
RXAN
RXAP
TXAP1
TXAN1
TXAP2
TXAN2
600
+
600
+
1200
C1
R3
R3
R2
R3
R3
R2
Figure 19: Dual transmitter arrangement
R1
R1
Z4
Z4
RW
ZL
73M1903C Data Sheet
41