Overview of onsemi DM74S09N

The onsemi DM74S09N is a member of the 74S series of logic devices, known for their high-speed and high-performance bipolar transistor-transistor logic (TTL) design. Specifically, the DM74S09N is a quadruple 2-input AND gate with open-collector outputs. This device integrates four independent AND gates, each with two inputs, and each output is an open-collector transistor, allowing wired-AND logic functions and interfacing with various voltage levels or external pull-up resistors. The device is packaged in a standard 16-pin Dual In-line Package (DIP) which facilitates ease of integration into digital circuits.

Functional Description

The DM74S09N operates by performing the logical AND function on two input signals per gate. Each gate’s output transistor is of an open-collector type, meaning the output transistor pulls the output line low when activated but does not drive it high; instead, an external pull-up resistor is required to pull the output to a high level when the transistor is off. This characteristic makes the DM74S09N especially useful in wired-AND applications, open-drain configurations, and bus-oriented systems where multiple outputs can be connected together without conflict.

Key Specifications

* Number of Gates: 4 independent AND gates
* Inputs per Gate: 2
* Output Type: Open-collector NPN transistor
* Supply Voltage (Vcc): Typically 5 V ± 0.5 V
* Input Voltage Levels: Compatible with standard TTL input thresholds
* Propagation Delay: Approximately 10 ns typical (varies slightly by manufacturer and operating conditions)
* Operating Temperature Range: 0°C to 70°C (commercial grade)
* Input Current: Typically 20 µA at standard input logic levels
* Output Current: Can sink up to 20 mA per output transistor, making it suitable for driving LEDs or relay coils through appropriate resistors
* Power Dissipation: Typically 500 mW maximum per device
* Package Type: 16-pin Dual In-line Package (DIP), also available in surface mount variants depending on the supplier

Electrical Characteristics

The device exhibits TTL input voltage levels with guaranteed noise margins, making it compatible with most TTL families. The open-collector output transistor can pull the output line down to near ground potential when active, and the external pull-up resistor defines the high-level voltage. The maximum sink current capability allows the device to directly drive loads such as LED segments or relays within its specified current limits.

Applications

Due to its open-collector outputs and fast switching speed, the DM74S09N is widely used in:

* Wired-AND logic configurations for bus systems or multiple output lines combined on a single wire
* Interfacing with higher voltage or different logic families through external pull-ups
* Driving loads that require current sinking such as LED indicators or small relays
* Logic level shifting and open-collector bus driver functions
* Systems where multiple outputs must share a common line without electrical conflicts

Pin Configuration and Description

* Pins 1, 2: Inputs for Gate 1
* Pin 3: Output for Gate 1 (open-collector)
* Pins 4, 5: Inputs for Gate 2
* Pin 6: Output for Gate 2
* Pin 8, 9: Inputs for Gate 3
* Pin 10: Output for Gate 3
* Pins 11, 12: Inputs for Gate 4
* Pin 13: Output for Gate 4
* Pin 7: Ground (GND)
* Pin 16: Positive Supply Voltage (Vcc)

Thermal and Mechanical Properties

The 16-pin DIP package provides a robust and easy-to-handle form factor. It is suitable for through-hole mounting on printed circuit boards (PCBs). Thermal resistance junction-to-ambient is typically around 85 °C/W, necessitating proper PCB design considerations when driving higher loads to ensure device reliability. The device’s plastic body meets industry standards for mechanical durability and electrical insulation.

Timing Characteristics

The DM74S09N features propagation delays in the range of about 10 nanoseconds from input change to output response under nominal supply and load conditions. This speed classifies it as a “fast” TTL logic device, making it suitable for applications requiring moderate to high-speed logic operations without sacrificing compatibility with standard TTL logic levels.

Compatibility

This device is compatible with other 74S family devices and standard TTL logic levels. Its open-collector outputs allow it to be used with pull-up voltages higher than 5 V (within certain limits), providing flexibility in mixed-voltage environments. The device is also pin-compatible with other quad 2-input AND gates, but the open-collector output distinguishes it functionally.

Summary

The onsemi DM74S09N is a versatile high-speed TTL logic device offering four independent 2-input AND gates with open-collector outputs, enabling wired-AND logic and bus-oriented applications. Its high sink current capacity, fast switching speed, and TTL compatibility make it a reliable choice for various digital logic circuit designs, especially when multiple devices must share a common output line or interface with higher voltage levels through external pull-ups. Packaged in a standard DIP form, it is easy to implement in prototyping and production environments alike.