HD74AC HITACHI [Hitachi Semiconductor], HD74AC Datasheet - Page 34

• Manufacturer Part Number: HD74AC
• Description: HD74AC Series Common Information
• Manufacturer: HITACHI [Hitachi Semiconductor]

ECL devices cannot directly drive FACT devices. Interfacing FACT-to-ECL can be accomplished by
using TTL-to-ECL translators and 10125 ECL-to-TTL translators in addition to following the same rules
on the TTL outputs to CMOS inputs (i.e., a resistor pull-up to V
translation can also be accomplished by a resistive network. A three-resistor interface between FACT and
ECL logic is illustrated in figure 4. Figures 5 and 6 show the translation from ECL-to-FACT, which is
somewhat more complicated. These two examples offer some possible interfaces between ECL and FACT
logic.
Figure 5 Single-Ended ECL-to-HD74AC Circuit
T1,T2 - 2SC641 (K)
D1,D2 - HP5082 - 2811
Figure 4 Resistive FACT-to-ECL Translation
AC/ACT
+5V
ECL
510
510
560
D1
470
T1
510
–5.2V
D2
CC
–5.2V
T2
270
of approximately 4.7 k ). The
5.0V
Vbb
AC
Design Considerations
33