DM7556 and DM8556 are two programmable 4-bit binary counters of TLF6588, with a typical clock frequency of 35MHz, TRI-STATE outputs, completely independent clear, synchronous loading and internal cascading circuitry.
This document is a technical datasheet for the National Semiconductor DM7556 and DM8556 integrated circuits. These devices are described as synchronous, edge-sensitive, fully-programmable 4-bit counters that feature both conventional totem-pole and TRI-STATE outputs.
The datasheet provides comprehensive electrical characteristics, including supply voltage ranges (4.5V to 5.5V), operating temperature limits (-55°C to +125°C for DM7556 and 0°C to +70°C for DM8556), and maximum clock frequencies up to 35 MHz typical. It details the function table, timing diagrams, switching characteristics, and physical dimensions for both Ceramic Dual-In-Line (J) and Molded Dual-In-Line (N) packages.
| Typical Clock Frequency | 35 MHz |
|---|---|
| Supply Voltage (DM7556) | 4.5V to 5.5V |
| Operating Temperature (DM7556) | -55°C to +125°C |
| Operating Temperature (DM8556) | 0°C to +70°C |
| Max Clock Frequency | 25 MHz |
The typical clock frequency is 35 MHz.
Yes, when the outputs are in the high impedance mode (TRI-STATE), they can be used to enter data from bus lines.