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TM109902 (5/03)
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3.8
INTEGRATED CIRCUIT SERVICE INFORMATION
A. Series 54/74 Integrated Circuits
Type-number identification is becoming increasingly complex for the 54/74 series of integrated
circuits, which were originally referred to as TTL chips. Today, many different type numbers
may apply to chips that perform the same function, although specifications (temperature, speed,
power, etc.) and interior configurations may be different. Usually, the only difference in the type
numbers involves the alpha characters immediately following the 54/74 designation.
Consider the quadruple D-type flip-flop chip 74LS175. This logic circuit may be manufactured
with type numbers 54175, 545175, 54LS175, 54AS175, 54ALS175, 54HC175, 54HCT175,
74175, 745175, 74AS175, 74ALS175, 74HC175, and 74HCT175. All these devices perform the
same logic function, but each has a different specification, different internal construction, and
are not interchangeable in all circuit applications. However, the pin arrangement and IC diagram
is usually the same for all these devices. Most chips are available in both 54 series and 74 series
type numbers. The 54 series have an operating temperature specification of -55°C to 125°C, and
the 74 series have a temperature specification of 0°C to 70°C. Table 3-4 describes the primary
differences corresponding to the alpha characters in the type number.
The 54HC175, 54HCT175, 74HC175, and 74HCT175 devices are CMOS versions of the above
and may be shown in a separate IC diagram.
The 54AC175 and 54ACT175 devices are advanced CMOS logic (ACL) versions of the above.
ACL matches bipolar FAST and AS in speed, performance, and logic type output drive, but at
CMOS power levels.
Integrated Circuit Diagrams
A small functional circuit diagram of each integrated circuit in the RT-1601 is provided in the
following figures. First, Table 3-6 contains a list or index of the circuit diagrams. Figure 3-2
illustrates all the various pin numbering configurations, and Figure 3-3 contains several sheets of
IC diagrams.
Column one of Table 3-6 lists alphanumerically each integrated circuit by the vendor type
number. Column two specifies the sheet of Figure 3-3 where the IC circuit diagram is located.
Column three contains the IC drawing reference number (IC33, IC297, etc.) which appears in
the upper left corner of each IC diagram.
Figure 3-2 illustrates the pin location drawings for the popular IC's. Pin connections are
numbered as viewed from the top of the IC case. A mark representing pin 1 is etched on the
circuit boards for proper orientation of the component. Each pin location drawing is identified
with a letter (A, B, C, etc.). The circuit diagram for each IC contains a reference to one of the
pin location drawings on Figure 3-2.
The type numbers appearing on the IC circuit diagrams in Figure 3-3 are representative vendor
types for the device. The actual vendor type number used in the equipment (listed in Table 3-6)
may be a different type number for the same device.
The document reference is online, please check the correspondence between the online documentation and the printed version.
