Low Power V.22 bis Modem
CMX868
1.3
Signal List
CMX868
D2/E2/P4
Signal
Name
Description
Pin No.
Type
XTALN
XTAL/CLOCK
RDRVN
O/P
The output of the on-chip Xtal oscillator inverter.
1
I/P
2
3
The input to the oscillator inverter from the Xtal
circuit or external clock source.
Relay drive output, low resistance pull down to
VSS when active and medium resistance pull up
to VDD when inactive.
O/P
VSS
RD
Power
I/P
4, 8, 12, 17, 21
5
The negative supply rail (ground).
Schmitt trigger input to the Ring signal detector.
Connect to VSS if Ring Detector not used.
Open drain output and Schmitt trigger input
forming part of the Ring signal detector.
Connect to VDD if Ring Detector not used.
RT
BI
6
VDD
Power The positive supply rail. Levels and thresholds
within the device are proportional to this
voltage.
7, 16, 24
RXAFB
RXAN
RXA
O/P
The output of the Rx Input Amplifier.
9
I/P
10
11
13
The inverting input to the Rx Input Amplifier
The non-inverting input to the Rx Input Amplifier
I/P
VBIAS
O/P
Internally generated bias voltage of
approximately VDD /2, except when the device
is in ‘Powersave’ mode when VBIAS will
discharge to VSS. Should be decoupled to VSS
by a capacitor mounted close to the device pins.
The inverted output of the Tx Output Buffer.
TXAN
TXA
O/P
O/P
I/P
14
15
18
19
The non-inverted output of the Tx Output Buffer.
The C-BUS chip select input from the mC.
The C-BUS serial data input from the mC.
CSN
COMMAND
DATA
I/P
SERIAL
CLOCK
I/P
20
22
The C-BUS serial clock input from the mC.
REPLY DATA
T/S
A 3-state C-BUS serial data output to the mC.
This output is high impedance when not sending
data to the mC.
IRQN
O/P
23
A ‘wire-ORable’ output for connection to a mC
Interrupt Request input. This output is pulled
down to VSS when active and is high impedance
when inactive. An external pullup resistor is
required ie R1 of Figure 2
ã 2004 CML Microsystems Plc
4
D/868/9
CMLMICRO [ CML MICROCIRCUITS ]
