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PDF MC1489 Data sheet ( Hoja de datos )
| Número de pieza | MC1489 | |
| Descripción | Quad line receivers | |
| Fabricantes | STMicroelectronics | |
| Logotipo |  |
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General features
s Input resistance –3k to 7kΩ
s Input signal range ± 30V
s Input threshold hysteresis built-in
s Response control:
a) Logic threshold shifting
b) Input noise filtering
Description
The MC1489 monolithic quad line receivers are
designed to interface data terminal equipment
with data communications equipment in
conformance with the specifications of EIA
Standard N° RS232C.
MC1489
MC1489A
Quad line receivers
DIP
SOP
Order code
April 2006
DIP14
MC1489P
MC1489AP
Part Number
Rev 4
SO14 (Tape & reel)
MC1489D1013TR
MC1488AD1013TR
1/
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17
1 page  
MC1489/MC1489A
3 Maximum ratings
Maximum ratings
Table 1. Absolute maximum ratings
Symbol
Parameter
VS
VI
IOL
PTOT
Tamb
Tstg
Power supply voltage
Input voltage range
Output load current
Power dissipation
Operating ambient temperature
Storage temperature range
Value
10
±30
20
1
0 to 75
-65 to 150
Unit
V
V
mA
W
°C
°C
Note:
Absolute Maximum Ratings are those values beyond which damage to the device may
occur. Functional operation under these condition is not implied.
Table 2. Thermal data
Symbol
Parameter
RthJA Thermal resistance junction-ambient Max
Plastic DIP14
200
SO14
165
Unit
°C/W
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5 Page 
MC1489/MC1489A
8 Application information
Application information
The Electronic Industries Association (EIA) has released the RS-232C specification
detailing the requirements for the interface between data processing equipment and data
communications equipment. This standard specifies not only the number and type of
interface leads, but also the voltage levels to be used. The MC1488 quad driver and its
companion circuit, the MC1489 quad receiver, provide a complete interface system between
DTL or TTL logic levels and the RS-232C defined levels. The RS-232C requirements as
applied to receivers are discussed herein.
The required input impedance is defined as between 3000Ω and 7000Ω for input voltages
between 3.0 and 25V in magnitude; and any voltage on the receiver input in an open circuit
condition must be less than 2.0V in magnitude. The MC1489 circuits meet these
requirements with a maximum open circuit voltage of one VBE.
The receiver shall detect a voltage between - 3.0 and - 25V as a Logic "1" and inputs
between + 3.0 and + 2.5V as a Logic "0". On some interchange leads, an open circuit of
power "OFF" condition (300Ω or more to ground) shall be decoded as an "OFF" condition or
Logic "1". For the reason, the input hysteresis thresholds of the MC1489 circuits are all
above ground. Thus an open or grounded input will cause the same output as a negative or
Logic "1" input.
8.1 Device characteristics
The MC1489 interface receivers have internal feedback from the second stage to the input
stage providing input hysteresis for noise rejection. The MC1489 input has typical turn-on
voltage of 1.25V and turn-off of 1.0 V for a typical hysteresis of 250mV. The MC1489A has
typical turn-on of 1.95V and turn-off of 0.8V for typically 1.15V of hysteresis.
Each receiver section has an external response control node in addition to the input and
output pins, thereby allowing the designer to vary the input threshold voltage levels. A
resistor can be connected between this node and an external power supply. Figure 4.,
Figure 6. and Figure 7. illustrate the input threshold voltage shift possible through this
technique.
This response node can also be used for the filtering of the high-frequency, high-energy
noise pulses. Figure 11. and Figure 12. show typical noise-pulse rejection for external
capacitors of various sizes.
These two operations on the response node can be combined or used individually for may
combinations of interfacing applications. The MC1489 circuits are particularly useful for
interfacing between MOS circuits and MDTL/MTTL logic systems. In this application, the
input threshold voltages are adjusted. (with the appropriate supply and resistor values) to
fall in the center of the MOS voltage logic levels (see Figure 13.).
The response node may also be used as the receiver input as long as the designer realizes
that he may not drive this node with a low impedance source to a voltage greater than one
diode above ground or less than one diode below ground. This feature is demonstrated in
Figure 14. where two receivers are slaved to the same line that must still meet the RS-232C
impedance requirement.
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| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet MC1489.PDF ] | |
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