74LS190 DIP Synchronous Up/Down Decade Counter
The 74LS190 is a high speed TTL integrated circuit that functions as a synchronous, reversible BCD decade counter. This device is designed to count in a Binary Coded Decimal sequence from 0 to 9 in both incrementing and decrementing modes. Because it is a synchronous counter, all flip-flops change state simultaneously on the low-to-high transition of the clock, provided the enable input is low. This synchronized operation eliminates the output glitches common in asynchronous ripple counters.
The counter features a dedicated Up/Down control input to set the direction of the count and a parallel load facility for presetting the counter to any desired BCD starting value. It also includes "Terminal Count" and "Ripple Clock" outputs, which simplify the process of cascading multiple 74LS190 units for high-speed multi-decade counting. Its low power Schottky construction makes it ideal for digital clocks, timers, and industrial control systems requiring bidirectional counting.
KEY FEATURES
- Synchronous counting for high speed and stable timing
- Reversible counting direction with Up/Down control
- Asynchronous parallel load for presetting any BCD value
- Cascadable for multi-decade counting without external gates
- No asynchronous master reset (Clear) for specific logic requirements
- Standard 16 pin dual in line package
SPECIFICATIONS
- Supply Voltage 4.75V to 5.25V
- Operating Temperature 0 to 70 Celsius
- Logic Type TTL Low Power Schottky
- Maximum Clock Frequency 20MHz
- Typical Power Dissipation 100mW
- High Level Output Current -0.4mA
- Low Level Output Current 8mA
INTERFACES
- CP Clock input positive edge triggered
- U/D Up-down count control input
- CE BAR Count enable input active low
- LOAD Parallel load input active low
- A B C D Parallel data inputs
- QA QB QC QD BCD counter outputs
- TC Terminal count output
- RC BAR Ripple clock output active low
- VCC Positive supply voltage
- GND Ground reference
