74190 IC Up/Down BCD Decade Counter
The IC 74190 is a synchronous 4-bit BCD (Binary-Coded Decimal) up/down counter that counts from 0000 (0) to 1001 (9) in either direction, depending on the Up/Down control input.
It features a parallel load (LOAD) input that allows presetting any initial value within the valid BCD range. When LOAD is active, the counter ignores clock pulses and loads the parallel data instead.
The synchronous operation ensures that all bits change state simultaneously on the clock edge, avoiding glitches. It includes carry (TCU) and borrow (TCD) outputs, enabling counters to be cascaded for multi-decade counting sequences.
With TTL logic compatibility and fast switching characteristics, the 74190 is used in digital clocks, frequency dividers, event counters, and numerical display systems.
Pin Configuration (DIP-16)
| Pin | Name | Description |
|---|---|---|
| 1 | TCD | Terminal Count Down (Borrow) Output |
| 2 | CP | Clock Input |
| 3 | P3 | Parallel Data Input (MSB) |
| 4 | P2 | Parallel Data Input |
| 5 | P1 | Parallel Data Input |
| 6 | P0 | Parallel Data Input (LSB) |
| 7 | Q0 | Output Bit 0 |
| 8 | GND | Ground |
| 9 | Q1 | Output Bit 1 |
| 10 | Q2 | Output Bit 2 |
| 11 | Q3 | Output Bit 3 (MSB) |
| 12 | LOAD | Parallel Load (active LOW) |
| 13 | CE | Count Enable |
| 14 | U/D | Up/Down Control |
| 15 | TCU | Terminal Count Up (Carry) Output |
| 16 | VCC | +5V Power Supply |
Key Features
Counts BCD (0–9) in up or down mode
Synchronous operation for glitch-free counting
Parallel load for preset values
Carry and borrow outputs for cascading
TTL-compatible inputs and outputs
High-speed counting capability
DIP-16 or SOIC-16 package
Applications
Build decade up/down counters for digital clocks.
Drive BCD-to-7-segment displays.
Divide frequencies in both directions.
Create programmable counters in control systems.
Cascade for multi-digit up/down counting.
Generate up/down sequences in automation.
Use in reversible event counting systems.
Implement bidirectional scoreboards.
Design elevator floor counters.
Teach up/down counting in digital logic labs.
Specifications Table
| Parameter | Value |
|---|---|
| Logic Family | TTL |
| Function | Synchronous BCD Up/Down Counter |
| Count Range | 0–9 (mod-10) |
| Inputs | CP, LOAD, CE, U/D, P0–P3 |
| Outputs | Q0–Q3, TCU, TCD |
| Input HIGH Voltage | ≥ 2.0V |
| Input LOW Voltage | ≤ 0.8V |
| Output HIGH Voltage | ≥ 2.4V |
| Output LOW Voltage | ≤ 0.4V ‘ |
| Propagation Delay | ~25 ns |
| Max Clock Frequency | ~35 MHz |
| Supply Voltage (Vcc) | 4.75V to 5.25V |
| Operating Temp | 0°C to 70°C |
| Package Type | DIP-16 / SOIC-16 |
| Number of Pins | 16 |
