MC14C89AB 데이터 시트보기 (PDF) - Motorola => Freescale
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MC14C89AB Datasheet PDF : 6 Pages
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MC14C89B, AB
APPLICATIONS INFORMATION
Description
The MC14C89AB and MC14C89B are designed to be
direct replacements for the MC1489A and MC1489. Both
devices meet all EIA–232 specifications and also the faster
EIA–562 and CCITT V.28 specifications. Noise pulse
rejection circuitry eliminates the need for most response
control filter capacitors but does not exclude the possibility as
filtering is still possible at the Response Control (RC) pins.
Also, the Response Control pins allow for a user defined
selection of the threshold voltages. The MC14C89AB and
MC14C89B are manufactured with a bipolar technology
m using low power techniques and consume at most 700 A,
plus load currents with a +5.0 V supply.
Outputs
The output low or high voltage depends on the state of the
inputs, the load current, the bias of the Response Control
pins, and the supply voltage. Table 1 applies to each receiver,
regardless of how many other receivers within the package
are supplying load current.
Table 1. Function Table
Receivers
Input*
Output*
H
L
L
H
*The asterisk denotes A, B, C, or D.
Receiver Inputs and Response Control
The receiver inputs determine the state of the outputs in
accordance with Table 1. The nominal VIL and VIH
thresholds are 0.95 V and 1.90 V respectively for the
MC14C89AB. For the MC14C89B, the nominal VIL and VIH
thresholds are 0.95 and 1.30, respectively. The inputs are
able to withstand ±30 V referenced to ground. Should the
input voltage exceed ground by more than ± 30 V, excessive
currents will flow at the input pin. Open input pins will
generate a logic high output, but good design practices
dictate that inputs should never be left open.
The Response Control (RC) pins are coupled to the inputs
through a resistor string. The RC pins provide for adjustment
of the threshold voltages of the IC while preserving the
amount of hysteresis. Figure 10 shows a typical application
to adjust the threshold voltages. The RC pins also provide
access to an internal resistor string which permits low pass
filtering of the input signal within the IC. Like the input pins,
the RC pins should not be taken above or below ground by
more than ± 30 V or excessive currents will flow at these pins.
The dependence of the low level threshold voltage (VIL) upon
RRC and Vbat can be described by the following equation:
]NJ * ƪ ) ƫNj VIL
W W V0.09
Vbat
505
RRC (1.6)
2.02 k
(1)
ȡ ) ȣ 5.32 kW
6.67 106 W2
RRC
ȧȢ ȧȤ 505 W
VIH can be found by calculating for VIL using equation (1)
then adding the hysteresis for each device (0.35 for the
MC14C89B or 0.95 V for the MC14C89AB). Figure 7 plots
equation (1) for two values of Vbat and a range of RRC.
If an RC pin is to be used for low pass filtering, the
capacitor chosen can be calculated by the equation,
] * CRC
2.02 kW 12p f 3dB
(2)
where f–3 dB represents the desired –3 dB role–off frequency
of the low pass filter.
Figure 9. Application to Adjust Thresholds
Input Pin
Response Control Pin
RRC
+
– Vbat
Another feature of the MC14C89AB and MC14C89B is
input noise rejection. The inputs have the ability to ignore
m pulses which exceed the VIH and VIL thresholds but are less
than 1.0 s in duration. As the duration of the pulse exceeds
m 1.0 s, the noise pulse may still be ignored depending on its
amplitude. Figure 8 is a graph showing typical input noise
rejection as a function of pulse amplitude and pulse duration.
Figure 8 reflects data taken for an input with an unconnected
RC pin and applied to the MC14C89AB and MC14C89B.
Operating Temperature Range
The ambient operating temperature range is listed as
–40°C to +85°C, and the devices are designed to meet the
EIA–232–E, EIA–562 and CCITT V.28 specifications over
this temperature range. The timing characteristics are
guaranteed to meet the specifications at +25°C. The
maximum ambient operating temperature is listed as +85°C.
However, a lower ambient may be required depending on
system use (i.e., specifically how many receivers within a
package are used), and at what current levels they are
operating. The maximum power which may be dissipated
within the package is determined by:
+ PD(max)
TJ(max) – TA
RqJA
where: RθJA = thermal resistance (typ., 100°C/W for the
DIP and 125°C/W for the SOIC packages);
TJ(max) = maximum operating junction temperature
(150°C); and
TA = ambient temperature.
PD = {[(VCC – VOH) IOH] or
[(VOL) IOL]}each receiver + (VCC ICC)
where: VCC = positive supply voltage;
VOH, VOL = measured or estimated from Figure 2
and 3;
ICC = measured quiescent supply current.
As indicated, the first term (in brackets) must be calculated
and summed for each of the four receivers, while the last
term is common to the entire package.
MOTOROLA ANALOG IC DEVICE DATA
5
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