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 74HCT123D-Q100J are not functionally interchangeable. The 74HCT14D is a hex inverting Schmitt trigger, while the 74HCT123D-Q100J is a dual retriggerable monostable multivibrator. They differ in logic function, channel count, output behavior, and package footprint, so direct substitution is not possible without circuit redesign.
Different logic function
Different channel count
Different output behavior
Different package footprint
Parts at a glance
Part B
74HCT123D-Q100J
Nexperia USA Inc.
- Lifecycle
- Active
- Stock
- 7163 Stückzahl
- Package
- SOIC-16
- Series
- Logic-Multivibrators
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 | 74HCT123D-Q100J | Why it matters |
|---|---|---|---|
| Logic Function | Hex inverting Schmitt trigger | Dual retriggerable monostable multivibrator | The core logic function determines whether the parts can substitute for each other in a circuit; these devices perform fundamentally different operations. |
| Number of Circuits | 6 | 2 | The number of independent channels affects how many signals can be processed and the required board space. |
| Output Type | Digital (inverted) | Digital pulse (monostable) | The output behavior must match the intended signal conditioning or timing function in the target application. |
| Propagation Delay | Typically 21 ns at 4.5 V | Typically 35 ns at 4.5 V | Propagation delay influences maximum operating frequency and timing margins in synchronous or pulse-generation circuits. |
| Supply Voltage Range | 4.5 V to 5.5 V | 4.5 V to 5.5 V | Both parts operate over the standard 5 V HCT range, so supply compatibility is not a differentiator. |
| Output Current (High/Low) | ±4 mA | ±4 mA | Drive strength determines the ability to interface with other logic families or loads; identical ratings mean similar fan-out capability. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | The temperature range must cover the application environment; both parts meet the same industrial/automotive-grade window. |
| Package / Mounting | SO-14 (surface mount) | SO-16 (surface mount) | Package footprint and pin count affect PCB layout and cannot be interchanged without redesign. |
| Qualification | Standard commercial | AEC-Q100 automotive qualified | Automotive qualification indicates enhanced reliability and testing for harsh environments, which may be required in automotive designs. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HCT14D | 74HCT123D-Q100J |
|---|---|---|
| Supplier | - | Nexperia USA Inc. |
| Series | 74HCT | Automotive, AEC-Q100, 74HCT |
| Part Status | Active | Active |
| Logic Type | Inverter | Monostable |
| Independent Circuits | - | 2 |
| Schmitt Trigger Input | - | Yes |
| Propagation Delay | - | 65 ns |
| Current - Output High Low | 4mA, 4mA | 4mA, 4mA |
| Voltage - Supply | 4.5V ~ 5.5V | 4.5 V ~ 5.5 V |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 125°C |
| 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 74HCT123D-Q100J?
The 74HCT14D is a hex inverting Schmitt trigger, providing six independent inverter channels with hysteresis for noise immunity and signal conditioning. The 74HCT123D-Q100J is a dual retriggerable monostable multivibrator (one-shot) that generates output pulses of a defined width set by external RC components. They serve fundamentally different logic functions and are not functionally interchangeable.
Are the 74HCT14D and 74HCT123D-Q100J pin-compatible in the SO14 package?
No. Although both devices are offered in a 14-pin SO package, their pinouts differ. The 74HCT14D follows the standard hex inverter pinout with inputs on pins 1, 3, 5, 9, 11, 13 and outputs on pins 2, 4, 6, 8, 10, 12, plus VCC on pin 14 and GND on pin 7. The 74HCT123D-Q100J has a different pin assignment including trigger inputs, reset inputs, and external timing component connections (Cext/Rext), so the two cannot be dropped into the same PCB footprint without redesign.
What is the difference in propagation delay between the 74HCT14D and the 74HCT123D-Q100J?
The 74HCT14D exhibits a typical propagation delay (tPD) of approximately 11 ns to 19 ns depending on supply voltage and load, as specified in the Nexperia datasheet. The 74HCT123D-Q100J output pulse width is determined by the external timing resistor and capacitor (tW ≈ 0.45 × Rext × Cext), and its propagation delay from trigger to output is typically in the range of 20 ns to 30 ns. These timing parameters are not directly comparable because the devices perform different logic functions.
Does the 74HCT123D-Q100J have automotive qualification while the 74HCT14D does not?
Yes. The 74HCT123D-Q100J carries the Q100 suffix, indicating it is qualified to the AEC-Q100 standard for automotive applications, as stated in the Nexperia product datasheet. The standard 74HCT14D is a commercial-grade logic device and is not AEC-Q100 qualified. An automotive-qualified version of the 74HCT14 (such as 74HCT14-Q100) would be required for automotive use.
Can the 74HCT14D be used to debounce a mechanical switch before triggering the 74HCT123D-Q100J?
Yes. The Schmitt trigger inputs of the 74HCT14D provide hysteresis that cleanly squares up slow or noisy edges from mechanical switches, and its output can directly drive the trigger input of the 74HCT123D-Q100J. This is a common signal-conditioning arrangement. The designer must verify that the 74HCT14D output levels and the 74HCT123D-Q100J trigger input thresholds are compatible at the chosen supply voltage, which they are for standard 5 V HCT logic.
What supply voltage range do both the 74HCT14D and 74HCT123D-Q100J support?
Both devices are HCT-family logic and operate over a recommended supply voltage range of 4.5 V to 5.5 V, with 5 V being the nominal value. This is specified in the respective Nexperia datasheets. They are not designed for 3.3 V operation, although HCT inputs are TTL-voltage compatible at 5 V supply.
How does the output drive capability compare between the 74HCT14D and the 74HCT123D-Q100J?
Both devices provide standard HCT-family output drive. The 74HCT14D datasheet specifies ±4 mA output current at 5 V supply. The 74HCT123D-Q100J datasheet specifies ±4 mA output current at 5 V supply for the Q output. The complementary outputs of the 74HCT123D-Q100J (Q and Qbar) have the same drive rating. Neither device is intended for high-current load driving without external buffering.
Can the 74HCT123D-Q100J be retriggered while the 74HCT14D cannot perform any retriggering function?
Correct. The 74HCT123D-Q100J is a retriggerable monostable multivibrator, meaning a new trigger pulse during the output pulse period extends the output pulse width. This is a defined feature of the device per the Nexperia datasheet. The 74HCT14D is a Schmitt trigger inverter with no timing or retriggering capability; it simply inverts and conditions the input signal with hysteresis.