73M2901/5V
Advanced Single
Chip Modem
12

T

Line

T1

5.1K

R4R3

21K

R1

TXAP

RXA

TXAN

475 C1

0.033m

Midcom 671-8005

Recommended Line Interface
R2
21K
PRI
R4
470
R3
5.1K
C4
100nF
GND
JP1
HEADER 10
1
2
3
4
5
6
7
8
9
10
R1
10K
GND
VCC
GND
R13
nc
Y1
11.0592 MHZ
U1
2901_P32
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
ASRCH
RING
RELAY
RI
VND
VPD
DCD
DSR
CTS
RTS
USR11
USR10/LIU
RST
HBDEN
VPA
TXAN
TXAP
VREF
VBG
RXA
VNA
VND
OSCOUT
OSCIN
VPD
VND
TXD
TXC
VPD
RXD
RXC
DTR
VPA
VNA
VCC
VCC
+
C2
10uF
1
2
T1
671-8005
1
4
2
3
To
--> RS232
level shifter
--> Host
microprocessor
VCC
R12
0R

TTL V24

signals

interface

R11
0R
C7
.033UF
SEC
C5
100nF
C1
27PF
C3
33PF
GND
GND
Recommended Schematics Arrangement