Part A
74VHC14MX
Công ty bán dẫn Fairchild
- Lifecycle
- Active
- Stock
- 3753 PCS
- Package
- SOIC-14
- Series
- Logic - Gates and Inverters
Replacement verdict
Not a drop-in replacement
The 74VHC14MX and 74VHC08MX are not functionally interchangeable despite sharing the same VHC logic family and SOIC-14 package. The 74VHC14MX provides six inverting Schmitt-trigger buffers with hysteresis, while the 74VHC08MX provides four 2-input AND gates with standard CMOS input thresholds. The differing logic function, channel count, input threshold behavior, and output drive characteristics make direct substitution impossible without circuit redesign.
Different logic function
Different channel count
Different input threshold
Different output drive
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74VHC14MX | 74VHC08MX | Why it matters |
|---|---|---|---|
| Logic Function | Hex Inverter with Schmitt Trigger Inputs | Quad 2-Input AND Gate | Defines the fundamental logic operation; these devices are not functionally interchangeable. |
| Number of Gates/Channels | 6 | 4 | Determines how many independent signal paths are available in a single package. |
| Number of Inputs per Gate | 1 | 2 | Affects the logic capability and pin usage for each gate element. |
| Schmitt Trigger Input | Yes | No | Schmitt trigger inputs provide hysteresis for noise immunity and slow signal edges. |
| Output Type | Inverting | Non-Inverting | Determines the polarity of the output relative to the input signal. |
| Supply Voltage Range | 2.0 V to 5.5 V | 2.0 V to 5.5 V | Defines the compatible power supply window for the device. |
| Logic Family | VHC | VHC | Ensures compatible voltage levels and switching characteristics with other VHC devices. |
| Package Type | SOIC-14 | SOIC-14 | Determines PCB footprint and assembly compatibility. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Specifies the environmental conditions under which the device operates reliably. |
| Mounting Type | Surface Mount | Surface Mount | Indicates the required board assembly method. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74VHC14MX | 74VHC08MX |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Part Status | Active | Active |
| Series | 74VHC | - |
| Logic Type | Inverter | - |
| Number of Circuits | 6 | - |
| Number of Inputs | 1 | - |
| Features | Schmitt Trigger | - |
| Voltage - Supply | 2V ~ 5.5V | - |
| Current - Quiescent (Max) | 2 µA | - |
| Current - Output High Low | 8mA, 8mA | - |
| Logic Level - Low | 0.9V ~ 1.65V | - |
| Logic Level - High | 2.2V ~ 3.85V | - |
| Max Propagation Delay @ V Max CL | 10.6ns @ 5V, 50pF | - |
| Operating Temperature | -40°C ~ 85°C | - |
| Mounting Type | Surface Mount | - |
Frequently asked questions
What are the primary functional differences between the 74VHC14MX and the 74VHC08MX?
The 74VHC14MX contains six independent Schmitt-trigger inverters, providing hysteresis for slow or noisy input signals. The 74VHC08MX contains four independent 2-input AND gates. They are not functionally equivalent and cannot be used interchangeably without redesigning the surrounding logic.
Do the 74VHC14MX and 74VHC08MX share the same package and pinout?
Both devices are offered in the SOIC-14 package by onsemi, but their internal die and pin functions differ. The 74VHC14MX uses all 14 pins for six inverters plus power and ground, while the 74VHC08MX uses the same 14-pin outline for four AND gates plus power and ground. Pin-to-pin compatibility is therefore not guaranteed.
What are the recommended operating voltage ranges for these devices?
Both the 74VHC14MX and 74VHC08MX are specified for a supply voltage range of 2.0 V to 5.5 V, with typical operation at 3.3 V or 5.0 V. This makes them suitable for mixed-voltage logic designs within that range.
How do the propagation delays of the 74VHC14MX and 74VHC08MX compare?
At a 5.0 V supply and 25°C, the 74VHC14MX typically exhibits a propagation delay of about 8.5 ns, while the 74VHC08MX typically exhibits about 5.5 ns. The AND gate is generally faster because it lacks the intentional hysteresis of the Schmitt-trigger inverter.
Can the 74VHC14MX be used to clean up noisy signals before feeding the 74VHC08MX?
Yes. The Schmitt-trigger inputs of the 74VHC14MX provide defined switching thresholds and hysteresis, which can square up slow or noisy edges. The resulting clean logic levels can then drive the inputs of the 74VHC08MX in a mixed-signal or interface circuit.
Are the 74VHC14MX and 74VHC08MX pin-compatible with older 74HC or 74AHC equivalents?
Functionally, the 74VHC14MX is compatible with 74HC14 and 74AHC14 Schmitt inverters, and the 74VHC08MX is compatible with 74HC08 and 74AHC08 AND gates, provided the supply voltage and timing requirements are met. However, direct substitution should always be verified against the specific manufacturer datasheet because input thresholds and drive strengths may differ.
What are the output drive capabilities of these two devices?
Both the 74VHC14MX and 74VHC08MX provide standard VHC-family output drive, typically ±8 mA at 5.0 V. This is sufficient for driving moderate capacitive loads and standard CMOS inputs, but not for high-current loads such as LEDs or relays without external buffering.
Which device is better for debouncing a mechanical switch?
The 74VHC14MX is better suited for debouncing because its Schmitt-trigger inputs tolerate slow rise and fall times and provide hysteresis to reject contact bounce. The 74VHC08MX, as a standard AND gate, does not have Schmitt-trigger inputs and may produce multiple output transitions if fed a noisy or slow edge.