4-Level FSK Modem Data Pump
Page 7 of 50
MX929B PRELIMINARY INFORMATION
2. Signal List
Pin No.
Signal
IRQ
Type
output
Description
1
A 'wire-ORable' output for connection to the host PC's Interrupt
Request input. When active, this output has a low impedance
pull down to V . It has high impedance when inactive.
SS
2
3
4
5
6
7
8
9
10
D7
D6
D5
D4
D3
D2
D1
D0
BUS
BUS
BUS
BUS
BUS
BUS
BUS
BUS
input
Pins 2-9 (D7-D0) are 8-bit, bi-directional,
3-state PC interface data lines
Read. An active low logic level input used to control the reading
RD
of data from the modem into the host PC.
11
input
Write. An active low logic level input used to control the writing
WR
of data into the modem from the host PC.
12
13
V
power Negative supply (ground).
SS
input
Chip Select. An active low logic level input to the modem used
CS
to enable a data read or write operation.
Logic level modem register select input
Logic level modem register select input
14
15
16
A0
A1
XTAL
input
input
output Output of the on-chip oscillator.
17
XTAL/CLOCK
input
Input to the on-chip oscillator, for an external Xtal circuit or
clock.
18
DOC 2
DOC 1
TXOUT
output Connection to the Rx level measurement circuitry. Should be
capacitive coupled to V
.
SS
19
output Connection to the Rx level measurement circuitry. Should be
capacitive coupled to V
SS
20
21
output Tx signal output from the modem.
V
BIAS
output A bias line for the internal circuitry held at V /2. This pin must
DD
be bypassed to V by a capacitor mounted close to the device
SS
pins.
22
23
24
RXIN
RXAMPOUT
input
Input to the Rx input amplifier.
output Output of the Rx input amplifier.
power Positive supply. Levels and voltages are dependent upon this
V
DD
supply. This pin should be bypassed to V by a capacitor
mounted close to the device pins.
SS
Note: Internal protection diodes are connected from each signal pin to V and V
.
DD
SS
©2001 MX-COM, INC.
www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. # 20480171.003
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