Part A
74HCT04D
Toshiba Semiconductor et stockage
- Lifecycle
- Active
- Stock
- 4496 PCS
- Package
- SOIC-16
- Series
- Logique - portes et Onduleurs
Replacement verdict
Not a drop-in replacement
The 74HCT540D and 74HCT04D are not functionally interchangeable despite sharing the 74HCT logic family and similar SOIC-14 packaging. The 74HCT540D is an octal inverting 3-state buffer with dual active-low output enable pins, while the 74HCT04D is a hex inverting gate with no 3-state capability. Their channel counts, output drive architectures, and pin functions differ fundamentally, so substituting one for the other requires board-level redesign rather than a direct drop-in swap.
Different output type
Different channel count
Different pin function
Different drive architecture
Parts at a glance
Part B
74HCT540D
Toshiba Semiconductor et stockage
- Lifecycle
- Active
- Stock
- 1645 PCS
- Package
- SOIC-14
- Series
- Logique - Buffers, lecteurs, récepteurs, émetteurs - récepteurs
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HCT540D | 74HCT04D | Why it matters |
|---|---|---|---|
| Logic Function | Octal inverting buffer/line driver with 3-state outputs | Hex inverter | Defines the core function; these devices are not functionally interchangeable because one is a 3-state octal buffer and the other is a simple hex inverter. |
| Number of Channels | 8 | 6 | Channel count determines how many independent signal lines can be processed, affecting circuit design and board layout. |
| Output Type | 3-state | Push-pull | 3-state outputs allow bus sharing and high-impedance disconnection, while push-pull outputs cannot be tied together without contention. |
| Output Drive Current (IOH/IOL) | ±6 mA | ±4 mA | Drive current determines the ability to drive loads and fan-out; the 74HCT540D can source/sink more current than the 74HCT04D. |
| Propagation Delay (tPD) | Typical 12 ns at 5 V | Typical 9 ns at 5 V | Propagation delay affects maximum operating frequency and timing margins in synchronous systems. |
| Control Inputs | Two active-low output enable pins (OE1, OE2) | None | Enable pins allow the outputs to be placed in high-impedance state for bus multiplexing, a feature absent in the 74HCT04D. |
| Supply Voltage Range | 4.5 V to 5.5 V | 4.5 V to 5.5 V | Both devices operate from the same standard 5 V TTL-compatible supply, ensuring compatibility in mixed HCT logic designs. |
| Input Threshold Compatibility | TTL-compatible (HCT family) | TTL-compatible (HCT family) | TTL-compatible inputs allow direct interfacing with bipolar TTL logic without additional level shifting. |
| Package | SO14 (D package) | SO14 (D package) | Identical package and pin count simplify PCB footprint considerations, though pinouts differ functionally. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Both devices support industrial temperature ranges, making them suitable for harsh-environment applications. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HCT04D | 74HCT540D |
|---|---|---|
| Series | 74HCT | 74HCT |
| Part Status | Active | Active |
| Logic Type | Inverter | Buffer, Inverting |
| Number of Circuits | 6 | - |
| Number of Inputs | 1 | - |
| Voltage - Supply | 4.5V ~ 5.5V | 4.5V ~ 5.5V |
| Current - Quiescent (Max) | 1 µA | - |
| Current - Output High Low | 4mA, 4mA | 6mA, 6mA |
| Logic Level - Low | 0.8V | - |
| Logic Level - High | 2V | - |
| Max Propagation Delay @ V Max CL | 16ns @ 5.5V, 50pF | - |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 85°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Number of Elements | - | 1 |
| Number of Bits per Element | - | 8 |
| Output Type | - | 3-State |
Frequently asked questions
What are the primary functional differences between the 74HCT540D and the 74HCT04D?
The 74HCT540D is an octal inverting buffer/line driver with 3-state outputs, while the 74HCT04D is a hex inverter with standard push-pull outputs. The 74HCT540D provides eight inverting channels with tri-state control for bus-oriented applications, whereas the 74HCT04D provides six inverting channels without tri-state capability.
Can the 74HCT540D and 74HCT04D be used interchangeably in a design?
No, they are not directly interchangeable. The 74HCT540D has 8 channels with 3-state outputs and two active-low output enable pins, while the 74HCT04D has 6 channels with always-active push-pull outputs. Pin counts, pinouts, and logic functions differ, so substitution requires circuit redesign and validation.
What are the package and pin count differences between the 74HCT540D and 74HCT04D?
The 74HCT540D is typically supplied in a 20-pin package such as SO20 or DIP20, reflecting its eight channels plus control pins. The 74HCT04D is typically supplied in a 14-pin package such as SO14 or DIP14, reflecting its six channels plus power pins. The "D" suffix in both part numbers generally denotes SOIC package variants from Nexperia.
Do the 74HCT540D and 74HCT04D operate at the same supply voltage and logic levels?
Yes, both are HCT-family devices and are specified for a 4.5 V to 5.5 V supply voltage range, with TTL-compatible input thresholds. This allows both to interface with 5 V TTL logic systems while providing CMOS-compatible output levels within the HCT family specifications.
What is the difference in output drive capability between the 74HCT540D and 74HCT04D?
Both devices are specified with standard HCT-family output drive, typically ±4 mA at 5 V per output according to manufacturer datasheets. The 74HCT540D is characterized as a line driver suitable for bus driving, while the 74HCT04D is a general-purpose inverter. Actual drive current should always be confirmed against the specific manufacturer datasheet.
When should the 74HCT540D be chosen over the 74HCT04D?
The 74HCT540D should be chosen when bus interfacing, tri-state output control, or higher channel count is required, such as driving a shared data bus where outputs must be placed in high-impedance state. The 74HCT04D is appropriate for simple signal inversion in applications not requiring tri-state control or eight channels.
Are the 74HCT540D and 74HCT04D compatible with the same logic families?
Both belong to the 74HCT logic family and are designed to be compatible with TTL and 5 V CMOS logic systems. They can interface with LSTTL and other 5 V logic families within the specified fan-out and loading limits defined in their respective datasheets.
What are the key electrical parameter differences to verify before comparing the 74HCT540D and 74HCT04D?
Key parameters to verify include propagation delay, input capacitance, output drive current, tri-state leakage current (applicable only to the 74HCT540D), and power dissipation. The 74HCT540D includes 3-state output leakage specifications that do not apply to the 74HCT04D, and channel counts differ (8 vs 6), affecting total power consumption.