GMSK Modem Data Pump
Page 5 of 37
MX909A PRELIMINARY INFORMATION
3 External Components
VDD
C1
VDD
1
24
23
22
21
20
19
18
17
16
15
14
13
IRQ
R2
R1
GMSKIN
RXAMPOUT
RXIN
2
3
D7
D6
D5
D4
D3
D2
D1
D0
RD
WR
V
BIAS
4
R4
GMSKOUT
TXOUT
DOC1
DOC2
XTAL/CLOCK
XTAL
A1
5
MX909A
6
7
8
9
C2
C6 C5
C7
10
11
12
A0
XTAL/CLOCK
VSS
CS
17
CS
A0
A1
C3
X1
R3
C4
16
XTAL
Figure 2: Recommended External Components
Component
Notes
Value
Tolerance
±20%
±10%
±20%
±5%
R1
R2
R3
R4
C1
C2
C3
C4
C5
C6
C7
X1
1
100kΩ
1MΩ
2
0.1 µF
0.1 µF
±20%
±20%
±20%
±20%
±10%
±20%
±20%
3
3
2
4
4
3
Recommended External Component Notes:
1. See section 4.1.10.
2. See section 4.1.12.
3. See section 4.4.3.
4. C6 and C7 values should satisfy the following formula:
-6
C (Farads) = 120 x 10 / Data Rate (bits/second)
Data Rate (kbits/sec)
C6 / C7 (uF)
4.0
4.8
8.0
9.6
16.0
19.2
0.03
0.022
0.015
0.012
0.0068
0.0068
¤2001 MX-COM, Inc.
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. # 20480134.005
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