73M1903C-EVM Maxim Integrated Products, 73M1903C-EVM Datasheet - Page 40

• 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: -

73M1903C Data Sheet
Next make the sum of R2 + R3 much higher than 600 Ω. Make sure they are lower than the input
impedance of the RXAP/RXAN pins; otherwise they can move the frequency response of the input filter.
So let R2 + R3 = 100 K Ω.
where
Use 1% resistors for R1, R2, and R3
To select the value for C1, make the zero at around 10 Hz.
The blocking cap Cblock should also have the same frequency response, but due to the low impedance,
its value will be much higher, usually requiring a polarized cap. A blocking cap will also be needed on the
modem side of the transformer if the DC offset current of the transmit pins will exceed the current rating of
the transformer. This is nearly always the case for applications using both transmit drivers since the
required transformers are dry types for most applications outside the U.S.
40
R3
Rwtot RW
R2 100 K
C1
C1 0.15 uF
Cblock
Cblock 27 uF
2 π . 100
.
TXAP1
TXAN1
1
2 π . 100
RXAN
RXAP
1
.
Rwtot
K C1
2 π . 600
100 K
.
1
1200
.
R3
K 10
1
Rohswitch
.
10
.
600
10
C1
R2
R3
R3
R2
2 Rbead
.
C1
R1
R1
Figure 18: Single Transmitter Arrangement
RW
Switch
Hook
DETECTOR
RING
Bead
Bead
RING
TIP
DS_1903C_033
Rev. 5.0