The 74LS390 IC contains a pair of high-speed 4-stage ripple counters. Each half of the LS390 is partitioned into a divide-by-two section and a divide-by five section, with a separate clock input for each section. The two sections can be connected to count in the 8.4.2.1 BCD code or they can count in a biquinary sequence to provide a square wave (50% duty cycle) at the final output. Each half of the LS393 operates as a Modulo-16 binary divider, with the last three stages triggered in a ripple fashion. the flip-flops are triggered by a HIGH-to-LOW transition of their CP inputs. The IC 74LS390 is much more compact in terms of chip size and provides much faster propagation speed which makes it reliable in every kind of device.
What is a Decade Counter?
A decade/BCD counter is a serial digital counter which can count up to 10 decimal digits. It goes through 10 unique combinations of output & RESETS for every new clock input. A BCD counter can count 0000, 0001, 0010, 1000, 1001, 1010, 1011, 1110, 1111, 0000, and 0001 and so on.
74LS390 Pinout
74LS390 Pin Configuration
| Pin No | Pin Name | Description |
|---|---|---|
| 1 | CP0′ | Active Low Clock Input to ÷2 counter |
| 2 | MR | Master Reset Input |
| 3 | Q0 | Flip-Flop output pin 0 |
| 4 | CP1′ | Active Low Clock Input to ÷2 counter |
| 5 | Q1 | Flip-Flop output pin 1 |
| 6 | Q2 | Flip-Flop output pin 2 |
| 7 | Q3 | Flip-Flop output pin 3 |
| 8 | GND | Ground Pin |
| 9 | Q3 | Flip-Flop output pin 3 |
| 10 | Q2 | Flip-Flop output pin 2 |
| 11 | Q1 | Flip-Flop output pin 1 |
| 12 | CP1′ | Active Low Clock Input to ÷5 counter |
| 13 | Q0 | Flip-Flop output pin 0 |
| 14 | MR | Master Reset Input |
| 15 | CP0′ | Active Low Clock Input to ÷2 counter |
| 16 | Vcc | Chip Supply Voltage |
74LS390 Features & Specifications
- Function: Decade Counter
- Bits (#): 4
- Technology Family: LS
- VCC (Min): 4.75V
- VCC (Max): 5.25V
- IOL (Max): 16mA
- IOH (Max): -0.4mA
- Low Power: 90 mW Typical Dissipation
- Dual Versions of LS290 and LS293
- LS390 has Separate Clocks Allowing ÷2, ÷2.5, ÷5
- Individual Asynchronous Clear for Each Counter
- Typical Max Count Frequency of 50 MHz
- Input Clamp Diodes Minimize High Speed Termination Effects
- Operating temperature range: 0°C to 70°C
- Input type: TTL
- Output type: CMOS
- Rating: Catalog
Applications
- Decade counters are generally used in devices such as clock circuits, frequency dividers, state machines, and sequencers, etc.
- Also used in devices such as LED chaser circuits.
You can download this datasheet for 74LS390 Dual 4-Bit Decade Counter IC from the link given below:
See Also: 74LS153 Dual 4 To 1 Line Multiplexer IC – Datasheet | 74LS132 Quad 2-Input Schmitt trigger NAND Gate IC – Datasheet | 74LS47 BCD to 7-Segment Display Decoder IC – Datasheet
