Part A
74HCT00D
東芝セミコンダクター・アンド・ストレージ
- Lifecycle
- Active
- Stock
- 1289 個数
- Package
- SOIC-20
- Series
- ロジック - ゲートおよびインバータ
Replacement verdict
Not a drop-in replacement
The 74HCT540D and 74HCT00D are not functionally interchangeable despite sharing the same 74HCT logic family and SOIC-14 package. The 74HCT540D is an octal inverting 3-state buffer with eight channels and dual output-enable control, while the 74HCT00D is a quad 2-input NAND gate with four independent logic gates. Their internal logic functions, channel counts, pin functions, and output drive characteristics differ fundamentally, so neither device can directly substitute for the other in an existing design without circuit redesign.
Different logic function
Different channel count
Different output type
Different pin function
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 | 74HCT00D | Why it matters |
|---|---|---|---|
| Logic Function | Octal buffer/line driver with 3-state outputs (inverting) | Quad 2-input NAND gate | The core logic function determines whether the parts are functionally interchangeable; these devices perform entirely different operations. |
| Number of Channels / Gates | 8 buffers | 4 gates | Channel count affects how many signals can be processed and the physical pin usage in a design. |
| Output Type | 3-state (tri-state) | Push-pull (totem-pole) | 3-state outputs allow bus sharing and high-impedance disconnection, while push-pull outputs cannot be tied together. |
| Input Configuration | Two active-low output enable pins (OE1, OE2) | Two inputs per gate | Input structure defines control signals and how the device is enabled or driven in a circuit. |
| Logic Polarity | Inverting | Inverting (NAND) | Polarity determines the output state relative to input, affecting signal integrity and logic design. |
| Supply Voltage Range (VCC) | 4.5 V to 5.5 V | 4.5 V to 5.5 V | Both parts operate in the standard 5 V TTL-compatible range, so power supply compatibility is identical. |
| Logic Family | HCT (High-speed CMOS, TTL-compatible) | HCT (High-speed CMOS, TTL-compatible) | Same logic family ensures compatible input thresholds and output drive characteristics. |
| Propagation Delay (tpd) | Typical 12 ns at 5 V | Typical 9 ns at 5 V | Propagation delay affects timing margins and maximum operating frequency in synchronous designs. |
| Output Drive Current (IOH/IOL) | ±6 mA | ±4 mA | Drive current determines the ability to drive loads such as LEDs, other logic inputs, or transmission lines. |
| Package / Pin Count | SOIC-20 (20 pins) | SOIC-14 (14 pins) | Different pin counts and footprints prevent direct drop-in replacement on the same PCB pad layout. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HCT00D | 74HCT540D |
|---|---|---|
| Series | 74HCT | 74HCT |
| Part Status | Obsolete | Active |
| Logic Type | NAND Gate | Buffer, Inverting |
| Number of Circuits | 4 | - |
| Number of Inputs | 2 | - |
| 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 | 17ns @ 5.5V, 50pF | - |
| Operating Temperature | -40°C ~ 85°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 74HCT00D?
The 74HCT540D is an octal inverting buffer/line driver with 3-state outputs, while the 74HCT00D is a quad 2-input NAND gate. The 74HCT540D is designed for bus driving and signal buffering with high-impedance output capability, whereas the 74HCT00D provides basic logic gating functions.
Are the 74HCT540D and 74HCT00D pin-compatible?
No. The 74HCT540D is typically supplied in a 20-pin package (e.g., SO20 or TSSOP20), while the 74HCT00D is supplied in a 14-pin package (e.g., SO14 or TSSOP14). Pin counts, pin assignments, and functions differ, so they are not drop-in replacements.
Can the 74HCT540D and 74HCT00D operate from the same supply voltage?
Yes. Both devices are members of the 74HCT logic family and are specified for a nominal supply voltage of 5 V, with typical operating ranges of 4.5 V to 5.5 V per manufacturer datasheets.
Does the 74HCT540D have 3-state outputs while the 74HCT00D does not?
Yes. The 74HCT540D features 3-state outputs controlled by two active-low output enable pins, allowing the outputs to be placed in a high-impedance state for bus sharing. The 74HCT00D has standard push-pull totem-pole outputs and no 3-state capability.
What is the logic function of each device?
The 74HCT540D provides eight inverting buffers with 3-state outputs. The 74HCT00D provides four independent 2-input NAND gates. Their logic functions are fundamentally different and not interchangeable.
Are both devices available in SO14 or SO20 surface-mount packages?
The 74HCT00D is commonly offered in a 14-pin SO package (SO14), while the 74HCT540D is commonly offered in a 20-pin SO package (SO20). Package options depend on the specific manufacturer and ordering code, so the exact package must be verified from the manufacturer datasheet.
Can the 74HCT540D be used to drive a bus while the 74HCT00D cannot?
Yes. The 74HCT540D is specifically intended for bus-oriented applications due to its 3-state outputs and higher output drive capability. The 74HCT00D is a general-purpose logic gate and is not designed for direct bus driving with high-impedance disconnection.
Do both devices have the same input threshold characteristics?
Yes. As 74HCT-family devices, both the 74HCT540D and 74HCT00D are specified with TTL-compatible input thresholds, typically VIH ≥ 2.0 V and VIL ≤ 0.8 V at VCC = 5 V, per the standard 74HCT specification.