Part A
74HCT00D
Toshiba Semiconductor và lưu trữ
- Lifecycle
- Active
- Stock
- 1289 PCS
- Package
- SOIC-20
- Series
- Logic - Gates and Inverters
Replacement verdict
Not a drop-in replacement
The 74HCT14D and 74HCT00D are not functionally interchangeable despite sharing the same 74HCT logic family and SO14 package. The 74HCT14D is a hex Schmitt-trigger inverter with hysteresis, while the 74HCT00D is a quad 2-input NAND gate. Their differing logic functions, gate counts, input threshold behavior, and pin signal assignments make direct substitution impossible without circuit redesign.
Different logic function
Different gate count
Different input threshold behavior
Different pin signal assignment
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HCT14D | 74HCT00D | Why it matters |
|---|---|---|---|
| Logic Function | Hex Inverting Schmitt Trigger | Quad 2-Input NAND Gate | Defines the fundamental logic operation; these devices are not functionally interchangeable as they perform entirely different logic functions. |
| Number of Gates | 6 | 4 | Determines how many independent logic elements are available in a single package, affecting circuit density and board layout. |
| Number of Inputs per Gate | 1 | 2 | Affects the logic capability of each gate and the complexity of functions that can be implemented per element. |
| Schmitt Trigger Input | Yes | No | Schmitt trigger inputs provide hysteresis for noise immunity and clean signal shaping, which standard gates do not offer. |
| Output Type | Inverting | NAND (inverting AND) | Determines the logic polarity of the output relative to inputs, which is critical for correct circuit behavior. |
| Supply Voltage Range | 4.5 V to 5.5 V | 4.5 V to 5.5 V | Defines the operating voltage window; both are HCT-family devices designed for 5 V TTL-compatible systems. |
| Logic Family | HCT (High-Speed CMOS, TTL compatible) | HCT (High-Speed CMOS, TTL compatible) | Ensures compatible input thresholds and output levels when interfacing with TTL logic. |
| Package | SO14 (SOIC-14) | SO14 (SOIC-14) | Identical package and pin count allow the same PCB footprint, though pinout functions differ. |
| Mounting Type | Surface Mount | Surface Mount | Both are surface-mount devices, suitable for the same assembly processes. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Indicates the environmental range over which both devices are specified to operate reliably. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HCT00D | 74HCT14D |
|---|---|---|
| Series | 74HCT | 74HCT |
| Part Status | Obsolete | Active |
| Logic Type | NAND Gate | Inverter |
| Number of Circuits | 4 | 6 |
| Number of Inputs | 2 | 1 |
| Voltage - Supply | 4.5V ~ 5.5V | 4.5V ~ 5.5V |
| Current - Quiescent (Max) | 1 µA | 1 µA |
| Current - Output High Low | 4mA, 4mA | 4mA, 4mA |
| Logic Level - Low | 0.8V | - |
| Logic Level - High | 2V | - |
| Max Propagation Delay @ V Max CL | 17ns @ 5.5V, 50pF | 31ns @ 5.5V, 50pF |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Features | - | Schmitt Trigger |
Frequently asked questions
What are the primary functional differences between the 74HCT14D and 74HCT00D?
The 74HCT14D contains six independent Schmitt-trigger inverters, providing hysteresis for slow or noisy input signals. The 74HCT00D contains four independent 2-input NAND gates without Schmitt-trigger inputs. They are not functionally equivalent and cannot be substituted for one another without redesigning the surrounding circuit.
Are the 74HCT14D and 74HCT00D pin-compatible?
No. Both are typically offered in a 14-pin SOIC package, but the internal gate arrangement and pin assignments differ. The 74HCT14D uses all 14 pins for six inverters (VCC and GND plus 12 signal pins), while the 74HCT00D uses 14 pins for four 2-input NAND gates (VCC and GND plus 12 signal pins). Pin functions are not interchangeable, so direct drop-in replacement is not possible.
Do both devices 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, with TTL-compatible input thresholds. They are intended for 5 V systems and can interface with TTL logic levels while driving CMOS-compatible outputs.
Which device should be used for debouncing a mechanical switch or cleaning up a noisy signal?
The 74HCT14D is the appropriate choice because its Schmitt-trigger inputs provide defined hysteresis, which improves noise immunity and ensures clean output transitions for slow edges. The 74HCT00D does not have Schmitt-trigger inputs and is not intended for that function.
Can the 74HCT00D be used to implement an inverter if both inputs are tied together?
Yes. A 2-input NAND gate with both inputs connected together functions as an inverter. However, this is not equivalent to a Schmitt-trigger inverter, so it does not provide the hysteresis of the 74HCT14D.
Are the 74HCT14D and 74HCT00D interchangeable in existing designs?
No. Because their logic functions, pin assignments, and input characteristics differ, they are not interchangeable. Any substitution requires a full review of the schematic, PCB layout, and timing requirements against the manufacturer datasheet.
Do both devices have the same output drive capability?
Both are standard HCT-family logic devices and typically provide symmetrical CMOS output drive suitable for driving other logic inputs. For exact output current ratings, refer to the specific manufacturer datasheet, as drive strength can vary slightly between manufacturers and operating conditions.
Which device is better for implementing combinational logic functions?
The 74HCT00D is intended for combinational logic because it provides four 2-input NAND gates, which can be combined to implement various logic functions. The 74HCT14D is intended for signal conditioning and inversion with hysteresis, not for general combinational logic design.