1200/2400bps MSK Modem for Trunked Radio Systems
15
MX429A
5.6 Bus Interface Timing
It is very important that circuit designs conform to the bus interface timing specification as described in
Section 6.1.4. Failure to do so can result in intermittent operation that is difficult to troubleshoot.
For example, if the bus timing is incorrect, the required two step READ Rx data transaction (1: Read Status
Register, 2: Read Rx Data Buffer) may fail on step 2. As a result, the MX429A IRQ will not be reset and
subsequently expected IRQ’s will not occur. This symptom might be incorrectly interpreted as an MX429A
functional failure but is, in fact, caused by the circuit design’s bus interface timing violation.
Other examples can occur on WRITE transactions that fail to properly clear the IRQ and so prevent
subsequently expected IRQ’s from occurring.
Circuit designs should be careful to strictly conform to the t
assumed requirements may be incorrect.
specification, the Data Hold Time (Write), as
DHW
5.6.1 Bus interface design migration from MX429 to MX429A
The MX429A bus interface timing requirements precisely match those of its predecessor, the MX429. As a
result, properly designed and operated MX429 bus interface circuits are compatible with the MX429A device.
It should be noted that the MX429 and MX429A device may behave differently in those designs, which
violate the bus timing specification. However, this is caused by the timing violation rather than an
incompatibility between the two devices.
6 Performance Specification
6.1 Electrical Performance
6.1.1 Absolute Maximum Ratings
Exceeding these maximum ratings can result in damage to the device.
General
Supply (V -V
Notes
Min.
Typ.
Max.
Units
)
-0.3
7.0
V
DD SS
Voltage on any pin to V
Current
-0.3
V
DD
+ 0.3
V
SS
V
-30
-30
-20
30
30
20
mA
mA
mA
DD
SS
V
Any other pin
J / P / LH Package
800
mW
Total allowable Power Dissipation at T
= 25ꢄC
AMB
10
Derating above 25ꢄC
Operating Temperature
Storage Temperature
mW/ꢄC above ꢄC
-40
-55
85
ꢄC
ꢄC
125
6.1.2 Operating Limits
Correct operation of the device outside these limits is not implied.
Notes
Min.
Typ.
Max.
Units
Supply (V -V
)
4.5
5.0
5.5
V
DD SS
Operating Temperature
Xtal Frequency
-40
85
ꢄC
4.032
MHz
© 1998 MX-COM Inc.
www.mxcom.com Tel: 800 638-5577 336 744-5050 Fax: 336 744-5054
Doc. # 20480128.007
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
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CMLMICRO [ CML MICROCIRCUITS ]
