Part A
74HCT14D
Toshiba Halbleiter und Speicher
- Lifecycle
- Active
- Stock
- 6342 Stückzahl
- Package
- SOIC-14
- Series
- Logic-Gates und Wechselrichter
Replacement verdict
Not a drop-in replacement
The 74HCT14D and 74HCT125D-Q100J are not functionally interchangeable. The 74HCT14D is a hex inverting Schmitt-trigger device, while the 74HCT125D-Q100J is a quad non-inverting buffer with 3-state outputs. They differ in logic function, channel count, output type, and package, so direct substitution is not possible without circuit redesign.
Different logic function
Different channel count
Different output type
Different package
Parts at a glance
Part B
74HCT125D-Q100J
Nexperia USA Inc.
- Lifecycle
- Active
- Stock
- 9544 Stückzahl
- Package
- SOIC-14
- Series
- Logic c Puffer, Treiber, Empfänger, Transceiver
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 | 74HCT125D-Q100J | Why it matters |
|---|---|---|---|
| Logic Function | Hex Inverting Schmitt Trigger | Quad Buffer with 3-State Outputs | Determines the fundamental signal-processing behavior; the two parts are not functionally interchangeable. |
| Number of Channels | 6 | 4 | Affects how many independent signal lines can be handled by a single package. |
| Output Type | Push-Pull (Inverting) | 3-State (Non-Inverting) | 3-state outputs allow bus sharing, while push-pull outputs cannot be tied together. |
| Input Type | Schmitt Trigger | Standard CMOS/TTL-compatible | Schmitt trigger inputs provide hysteresis for noisy or slow-rising signals; standard inputs do not. |
| Output Enable Control | No | Yes (active-low OE per channel) | Enable pins allow the output to be placed in high-impedance state for bus multiplexing. |
| Supply Voltage Range | 4.5 V to 5.5 V | 4.5 V to 5.5 V | Both operate from standard 5 V TTL-compatible supply rails. |
| Logic Family | HCT (High-Speed CMOS, TTL-compatible) | HCT (High-Speed CMOS, TTL-compatible) | Same logic family ensures compatible input thresholds and output drive levels. |
| Propagation Delay (typical) | ~19 ns at 5 V | ~14 ns at 5 V | Timing differences can affect signal integrity and maximum operating frequency in synchronous designs. |
| Qualification | Standard commercial | AEC-Q100 (automotive qualified) | Automotive qualification indicates enhanced reliability and temperature range for harsh environments. |
| Package | SO-14 (SOIC-14) | SO-14 (SOIC-14) | Same footprint allows drop-in PCB compatibility despite functional differences. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HCT14D | 74HCT125D-Q100J |
|---|---|---|
| Supplier | - | Nexperia USA Inc. |
| Series | 74HCT | Automotive, AEC-Q100, 74HCT |
| Part Status | Active | Active |
| Logic Type | Inverter | Buffer, Non-Inverting |
| Number of Elements | - | 4 |
| Number of Bits per Element | - | 1 |
| Output Type | - | 3-State |
| Current - Output High Low | 4mA, 4mA | 6mA, 6mA |
| Voltage - Supply | 4.5V ~ 5.5V | 4.5V ~ 5.5V |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Number of Circuits | 6 | - |
| Number of Inputs | 1 | - |
| Features | Schmitt Trigger | - |
| Current - Quiescent (Max) | 1 µA | - |
| Max Propagation Delay @ V Max CL | 31ns @ 5.5V, 50pF | - |
Frequently asked questions
What are the primary functional differences between the 74HCT14D and the 74HCT125D-Q100J?
The 74HCT14D is a hex inverting Schmitt trigger, providing six independent inverter channels with hysteresis for noise immunity on slow or noisy input signals. The 74HCT125D-Q100J is a quad buffer with 3-state outputs, providing four non-inverting buffer channels with active-LOW output enable pins, allowing high-impedance output states for bus sharing. They differ in logic function, channel count, output type, and input threshold behavior.
Are the 74HCT14D and 74HCT125D-Q100J pin-compatible?
No. Both are 14-pin devices, but their pinouts differ. The 74HCT14D uses a standard hex inverter pinout with inputs and outputs on opposite pins, while the 74HCT125D-Q100J uses a quad buffer pinout with output enable pins and a different input/output arrangement. They cannot be interchanged without PCB redesign.
What is the difference in output drive capability between these two devices?
Both devices are HCT-family CMOS logic. The 74HCT14D typically provides standard CMOS output drive, while the 74HCT125D-Q100J also provides standard CMOS output drive with 3-state capability. Exact drive currents should be verified from the respective manufacturer datasheets, as they may differ by manufacturer and operating conditions.
Does the 74HCT125D-Q100J have automotive qualification that the 74HCT14D lacks?
Yes. The suffix "-Q100" indicates automotive qualification according to the AEC-Q100 standard, typically for the Nexperia version of the 74HCT125D. The 74HCT14D, as a standard logic part number, does not carry this automotive qualification unless a specific manufacturer offers an automotive-grade variant with a different order code.
Can the 74HCT14D be used to clean up noisy signals while the 74HCT125D-Q100J cannot?
The 74HCT14D includes Schmitt trigger inputs with defined hysteresis, making it suitable for squaring up slow or noisy input signals. The 74HCT125D-Q100J has standard CMOS input thresholds without specified hysteresis, so it is not intended for signal conditioning of noisy or slow edges. This is a functional difference, not a limitation of the 125D for its intended buffer/line-driver applications.
What is the role of the output enable pins on the 74HCT125D-Q100J compared to the 74HCT14D?
The 74HCT125D-Q100J has active-LOW output enable (OE) pins for each of its four buffers. When OE is HIGH, the corresponding output enters a high-impedance state, allowing multiple devices to share a common bus. The 74HCT14D has no output enable pins; its six inverter outputs are always active.
Are both devices compatible with 5V TTL logic levels?
Yes. Both the 74HCT14D and 74HCT125D-Q100J are HCT-family devices, which means they are designed for 5V TTL-compatible input thresholds when operated at 5V VCC. This allows direct interfacing with TTL logic outputs while providing CMOS output levels.
Which device is more suitable for driving a shared data bus?
The 74HCT125D-Q100J is more suitable for shared bus applications because its 3-state outputs can be placed in high-impedance mode via the output enable pins, allowing multiple drivers on the same bus. The 74HCT14D has always-active outputs and cannot be tri-stated, so it is not intended for bus sharing without external multiplexing.