74145 IC BCD to Decimal Decoder DIP-16
The IC 74145 is a BCD (Binary-Coded Decimal) to decimal decoder and driver. It accepts a 4-bit binary input (representing values 0–9) and activates one of ten corresponding outputs by pulling it LOW, while all other outputs remain HIGH. Each output can sink current, enabling direct connection to low-side loads such as indicator lamps, relays, or Nixie tubes.
The outputs are active-low open-collector types, which support wired-AND connections and driving high-voltage loads through external resistors or transistors. The IC can only decode valid BCD inputs (0000 to 1001); inputs from 1010 to 1111 result in all outputs remaining HIGH.
The 74145 serves well in numeric display control, data routing, and decimal decoding. It offers high fan-out and noise immunity typical of TTL logic, making it reliable in timing and sequencing systems.
Key Features
Converts 4-bit BCD to 1-of-10 decimal outputs
Open-collector active-LOW outputs
Drives lamps, relays, Nixie tubes, or LED digits
TTL logic compatible
High fan-out capabilities
Easy interface with microprocessors or counters
DIP-16 or SOIC-16 standard packages
Applications
Drive one output line for each decimal digit (0–9)
Control numeric displays or Nixie tubes
Decode BCD counter outputs to decimal lines
Select devices or functions in sequence control circuits
Build simple keypad encoders and input selectors
Route digital signals to one of ten channels
Create decimal control panels in automation systems
Interface with sensors that output BCD signals
Develop programmable timers and event counters
Use in lab circuits for BCD-to-decimal demonstrations
Specifications Table
| Parameter | Value |
|---|---|
| Logic Family | TTL |
| Function | BCD to Decimal Decoder/Driver |
| Input Lines | 4 (A, B, C, D) |
| Output Lines | 10 (Y0 to Y9, active LOW) |
| Output Type | Open-collector |
| Fan-out (per output) | Typically 10 standard TTL loads |
| Input HIGH Voltage | ≥ 2.0V |
| Input LOW Voltage | ≤ 0.8V |
| Output LOW Voltage | ≤ 0.4V (at 8 mA sink current) |
| Propagation Delay | ~25 ns ‘ |
| Supply Voltage (Vcc) | 4.75V to 5.25V |
| Power Dissipation | ~115 mW |
| Operating Temperature | 0°C to 70°C |
| Package Type | DIP-16 / SOIC-16 |
| Number of Pins | 16 |
