CMX624 CML Microcircuits, CMX624 Datasheet - Page 10

• Manufacturer Part Number: CMX624
• Description: V.23-Bell 202 Modem
• Manufacturer: CML Microcircuits

V23 / Bell 202 Modem
1.5.8
This buffer amplifier, connected to the TXN, TXO and TXON pins, is intended for use as a Tx line driver as
shown in Section 1.6.1. Two symmetrical outputs are provided for use with a balanced load to give sufficient
Tx line signal levels even at low V
If the buffer is used as a balanced line driver, then bit 6 of the SETUP Register should be set to ‘1’ (TXON
output enabled). Setting bit 6 to ‘0’ disables the TXON output and the buffer draws less current from the
supply. When bit 6 is set to '0' the TXON pin should be left open circuit. N.B. The TXO output is unaffected by
this bit.
1.5.9
This block, which functions even in Zero Power mode, can be used to detect a telephone line Ring Signal or
Line Voltage Reversal and then generate a Interrupt Request signal to wake up the µC at the start of a call.
Suitable interface circuits are shown in Section 1.6.2.
The output of this block is the ‘Ring Detect’ line shown in Figure 1 which directly drives bit 6 of the FLAGS
Register. Any ‘0’ to ‘1’ or ‘1’ to ‘0’ change on this line will also set the ‘Ring Detect Change’ bit (5) of the
FLAGS Register.
If this block is not used, then the RD and RT pins should be connected to V
bit (5) of the IRQ MASK Register set to ‘0’.
2001 Consumer Microcircuits Limited
Transmit Output Buffer
Ring Signal Detector
dBm
-10
-20
-30
-40
-50
-60
-70
0
10
Figure 5 Maximum Out of Band Tx Line Energy Limits
DD
. If this is not required the TXON output can be disabled.
Bell 202
100
10
V23
1000
Hz
10000
SS
and the ‘Ring Detect Change’
100000
CMX624
D/624/6