MC14551B Просмотр технического описания (PDF) - Motorola => Freescale
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MC14551B Datasheet PDF : 9 Pages
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APPLICATIONS INFORMATION
Figure A illustrates use of the on–chip level converter
detailed in Figure 2. The 0–to–5 volt Digital Control signal is
used to directly control a 9 Vp–p analog signal.
The digital control logic levels are determined by VDD and
VSS. The VDD voltage is the logic high voltage; the VSS volt-
age is logic low. For the example, VDD = + 5 V = logic high at
the control inputs; VSS = GND = 0 V = logic low.
The maximum analog signal level is determined by VDD
and VEE. The VDD voltage determines the maximum recom-
mended peak above VSS. The VEE voltage determines the
maximum swing below VSS. For the example, VDD – VSS
= 5 volt maximum swing above VSS; VSS – VEE = 5 volt
maximum swing below VSS. The example shows a ± 4.5 volt
signal which allows a 1/2 volt margin at each peak. If voltage
transients above VDD and/or below VEE are anticipated on
the analog channels, external diodes (Dx) are recommended
as shown in Figure B. These diodes should be small signal
types able to absorb the maximum anticipated current
surges during clipping.
The absolute maximum potential difference between VDD
and VEE is 18.0 volts. Most parameters are specified up to
15 volts which is the recommended maximum difference be-
tween VDD and VEE.
Balanced supplies are not required. However, VSS must
be greater than or equal to VEE. For example, VDD =
+ 10 volts, VSS = + 5 volts, and VEE = – 3 volts is acceptable.
See the table below.
+5 V
–5 V
+5 V
EXTERNAL
CMOS
DIGITAL
CIRCUITRY
VDD VSS
VEE
9 Vp–p
ANALOG SIGNAL
0–TO–5 V DIGITAL
CONTROL SIGNAL
SWITCH
I/O
COMMON
O/I
MC14551B
CONTROL
9 Vp–p
ANALOG SIGNAL
+ 4.5 V
GND
– 4.5 V
Figure A. Application Example
VDD
VDD
Dx
SWITCH
I/O
Dx
Dx
COMMON
O/I
Dx
VEE
VEE
Figure B. External Schottky or Germanium Clipping Diodes
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ POSSIBLE SUPPLY CONNECTIONS
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ VDD
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ In Volts
VSS
In Volts
VEE
In Volts
Control Inputs
Logic High/Logic Low
In Volts
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ + 8
0
–8
+ 8/0
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ + 5
0
– 12
+ 5/0
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ + 5
0
0
+ 5/0
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ + 5
0
–5
+ 5/0
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ + 10
–5
+ 10/ + 5
Maximum Analog Signal Range
In Volts
+ 8 to – 8 = 16 Vp–p
+ 5 to – 12 = 17 Vp–p
+ 5 to 0 = 5 Vp–p
+ 5 to – 5 = 10 Vp–p
+ 10 to – 5 = 15 Vp–p
MOTOROLA CMOS LOGIC DATA
MC14551B
7
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