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The 74ALS161B is a synchronous presettable binary counter manufactured by Texas Instruments (TI).

Specifications:

• Logic Family: 74ALS
• Function: 4-bit synchronous binary counter
• Counting Mode: Synchronous
• Preset Capability: Parallel load (asynchronous)
• Clear Input: Asynchronous master reset
• Clock Input: Positive-edge triggered
• Operating Voltage (VCC): 4.5V to 5.5V
• Maximum Clock Frequency: ~32 MHz (typical)
• Propagation Delay: ~15 ns (typical)
• Output Drive Capability: Standard TTL
• Package Options: 16-pin DIP, SOIC

Descriptions:

The 74ALS161B is a high-speed 4-bit synchronous counter with parallel load and asynchronous reset functionality. It counts in binary from 0 to 15 (0000 to 1111) and can be preset to any value using the parallel load inputs. The counter advances on the rising edge of the clock signal when enabled.

Features:

• Synchronous Counting: All flip-flops change state simultaneously with the clock edge.
• Parallel Load (Preset): Allows loading a 4-bit value via inputs (A, B, C, D) when the LOAD input is low.
• Asynchronous Clear (Reset): Resets the counter to 0000 regardless of the clock when the CLR input is low.
• Carry Output (RCO): Provides a ripple carry signal when the counter reaches 1111 (15).
• Enable Inputs (P and T): Control counting (P enables carry, T enables counting).
• Compatible with TTL: Works with standard TTL logic levels.

This counter is commonly used in digital systems for frequency division, event counting, and timing applications.