7405 Hex Inverter Open Collector IC (DIP)

7405 Hex Inverter Open Collector IC (DIP)

The 7405 Hex Inverter Open Collector IC is a TTL logic device that contains six independent inverter gates (NOT gates) with open-collector outputs. Packaged in a DIP-14 through-hole format, the 7405 is convenient for prototyping, educational projects, and embedded designs that require reliable logic inversion combined with flexible output interfacing.

Key features of the 7405 Hex Inverter

• Six independent TTL inverters in a single DIP-14 package
• Open-collector outputs allow outputs to sink current but not source it
• Designed for 5V TTL logic levels (Vcc 4.75V to 5.25V)
• Typical propagation delay around 15 ns for fast switching
• Low power dissipation and high noise immunity
• Output current up to 16 mA per output (sink only)

Why choose a 7405 Hex Inverter Open Collector IC

The open-collector outputs make the 7405 especially useful when you need to:

• Create wired-AND logic by combining multiple outputs with a single pull-up resistor
• Level shift signals to higher voltages by using external pull-up resistors to the target voltage (within device limits)
• Directly drive LEDs or relays when paired with appropriate pull-up resistors and current-limiting components

Electrical specifications (summary)

• Logic family: 7400 series TTL
• Number of gates: 6
• Package: DIP-14 (Dual Inline Package)
• Output type: Open collector (sink only)
• Operating voltage (Vcc): 4.75V to 5.25V
• Maximum input voltage: 5.5V
• Maximum output sink current: 16 mA per output
• Propagation delay: ~15 ns (typical)
• Power dissipation: 500 mW (maximum)
• Operating temperature: 0°C to +70°C
• Pin count: 14

Practical usage notes and recommendations

• Always use an external pull-up resistor on open-collector outputs. Typical pull-up values range from 1 kΩ to 10 kΩ depending on desired current, speed and the pull-up voltage.
• When driving LEDs, include a suitable series resistor to limit current and avoid exceeding the 16 mA sink rating.
• For larger loads or when sourcing current is required, use a transistor or driver stage because the 7405 outputs cannot source current.
• Use a 0.1 µF bypass capacitor close to Vcc and GND pins to reduce supply noise and improve switching stability.
• Unconnected inputs should not be left floating; tie them high or low to prevent unpredictable switching and increased power consumption.

Typical applications for the 7405 Hex Inverter

• Logic signal inversion and conditioning in digital circuits
• Level shifting between TTL and higher-voltage domains using pull-ups
• Driving LEDs, relays and indicators with open-collector sinks
• Wired-AND implementations for simple bus arbitration or shared signaling
• Clock and timing circuits, digital control systems and test fixtures

Design tips

• Check that pull-up voltage does not exceed the device maximum input rating.
• If multiple outputs are tied together, ensure the combined sink current stays within package power and thermal limits.
• Consider using a buffered or CMOS equivalent if lower power or higher sourcing capability is required.

Note: Product images are for illustration purposes only.