Low Power V.22 bis Modem
CMX868
Transmit Output Level
Notes
Min.
-4.0
-2.0
Typ.
-3.0
-1.0
Max.
-2.0
0.0
Units
dBm
dBm
Modem and Single Tone modes
DTMF mode, Low Group tones
DTMF twist (level of high group tones wrt low
group) setting accuracy
7
7
7
7
-1.0
-0.25
-
–
+1.0
+0.25
dB
dB
Tx output buffer gain control accuracy
Notes:
5. % carrier frequency accuracy is the same as XTAL/CLOCK % frequency accuracy.
6
Tx signal % baud or bit rate accuracy is the same as XTAL/CLOCK % frequency
accuracy.
7. Measured between TXA and TXAN pins with Tx Level Control gain set to 0dB, 1k2W load
between TXA and TXAN, at VDD = 3.0V (levels are proportional to VDD - see section
1.4.2). Level measurements for all modem modes are performed with random
transmitted data and without any guard tone. 0dBm = 775mVrms.
0
-10
Bell 202
-20
-30
dBm
-40
-50
-60
-70
10
100
1000
Hz
10000
100000
Figure 14 Maximum Out of Band Tx Line Energy Limits (see note 8)
Notes:
8. Measured on the 2 or 4-wire line using the line interface circuits described in section
1.4.2 with the Tx line signal level set to -10dBm for QAM, DPSK, FSK or single tones, -
6dBm and -8dBm for DTMF tones. Excludes any distortion due to external components
such as the line coupling transformer.
ã 2004 CML Microsystems Plc
42
D/868/9
CMLMICRO [ CML MICROCIRCUITS ]
