Part A
74HC123D
Компания NXP USA Inc.
- Lifecycle
- Active
- Stock
- 3320 ПКС
- Package
- SOIC-16
- Series
- Логика - Мультивибраторы
Replacement verdict
Not a drop-in replacement
The 74HC14D,653 and 74HC123D are not functionally interchangeable despite sharing the 74HC logic family and SO14 package. The 74HC14D,653 is a hex inverting Schmitt trigger intended for signal conditioning and waveform shaping, while the 74HC123D is a dual retriggerable monostable multivibrator designed for pulse generation and timing. Their core functions, input/output behavior, and pinout definitions differ fundamentally, so substituting one for the other is not feasible without redesigning the surrounding circuit.
Different logic function
Different output behavior
Different pinout
Different timing architecture
Parts at a glance
Part B
74HC14D,653
Компания Nexperia USA Inc.
- Lifecycle
- Active
- Stock
- 3794 ПКС
- Package
- SOIC-14
- Series
- Логика - Ворота и инверторы
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC14D,653 | 74HC123D | Why it matters |
|---|---|---|---|
| Logic Function | Hex inverting Schmitt trigger | Dual retriggerable monostable multivibrator | Defines the core function; these devices are not functionally interchangeable as they perform entirely different logic operations. |
| Number of Circuits | 6 | 2 | Affects how many independent signal channels can be processed per package. |
| Output Type | Push-pull (standard CMOS) | Push-pull with complementary outputs (Q and Qbar) | Determines drive capability and whether complementary outputs are available for design flexibility. |
| Propagation Delay (typ.) | ~13 ns at 5 V | ~25 ns at 5 V | Impacts maximum operating frequency and timing margins in high-speed circuits. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both support the same HC-family voltage range, allowing use in 3.3 V and 5 V systems. |
| Output Current (max) | ±4 mA at 5 V | ±4 mA at 5 V | Determines the ability to drive loads such as LEDs or other logic inputs directly. |
| Package | SO-14 (SOIC-14) | SO-16 (SOIC-16) | Different pin counts and footprints prevent direct drop-in replacement on the same PCB pad layout. |
| Pin Count | 14 | 16 | Pin count mismatch means the devices cannot share the same socket or footprint. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Both meet industrial temperature requirements, suitable for harsh environments. |
| Schmitt Trigger Input | Yes (all inputs) | Yes (trigger inputs A and B) | Schmitt trigger inputs provide noise immunity and clean edge detection for slow or noisy signals. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC123D | 74HC14D,653 |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | Monostable | Inverter |
| Independent Circuits | 2 | - |
| Schmitt Trigger Input | Yes | - |
| Propagation Delay | 40 ns | - |
| Current - Output High Low | 5.2mA, 5.2mA | 5.2mA, 5.2mA |
| Voltage - Supply | 2 V ~ 6 V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 85°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) | - | 2 µA |
| Logic Level - Low | - | 0.3V ~ 1.2V |
| Logic Level - High | - | 1.5V ~ 4.2V |
| Max Propagation Delay @ V Max CL | - | 21ns @ 6V, 50pF |
Frequently asked questions
What are the primary functions of the 74HC14D,653 and the 74HC123D?
The 74HC14D,653 is a hex inverting Schmitt trigger, used for signal conditioning and waveform shaping of noisy or slow digital inputs. The 74HC123D is a dual retriggerable monostable multivibrator, used to generate precise output pulses of a defined width when triggered.
Can the 74HC14D,653 and 74HC123D be used interchangeably in a design?
No. They perform fundamentally different logic functions. The 74HC14D,653 provides inverting Schmitt trigger outputs, while the 74HC123D provides monostable pulse generation. Substitution requires a complete redesign of the surrounding circuit and validation against the target application.
What are the package and pin count differences between the 74HC14D,653 and 74HC123D?
The 74HC14D,653 is supplied in a 14-pin SOIC package (D suffix). The 74HC123D is supplied in a 16-pin SOIC package. The different pin counts and pinouts prevent direct PCB footprint compatibility.
How do the supply voltage and logic family specifications compare?
Both devices belong to the 74HC high-speed CMOS logic family and typically operate over a supply voltage range of 2.0 V to 6.0 V. However, detailed input threshold, propagation delay, and output drive specifications differ and must be verified from the respective manufacturer datasheets.
Does the 74HC14D,653 have Schmitt trigger inputs on all gates?
Yes. The 74HC14D,653 contains six independent inverters, each with Schmitt trigger input circuitry, providing hysteresis for noise immunity and clean switching of slow input signals.
What determines the output pulse width of the 74HC123D?
The output pulse width of the 74HC123D is determined by an external resistor (REXT) and capacitor (CEXT) connected to each monostable section. The pulse width is approximately tW = K × REXT × CEXT, where K is a constant specified in the manufacturer datasheet.
Are both devices compatible with standard CMOS and TTL logic levels?
The 74HC14D,653 and 74HC123D are CMOS devices with input thresholds that allow interfacing with standard CMOS outputs. Their compatibility with TTL logic levels depends on the specific supply voltage and must be confirmed from the datasheet input voltage specifications.
Which device is better suited for debouncing a mechanical switch?
The 74HC14D,653 is typically used for switch debouncing because its Schmitt trigger inputs provide hysteresis that cleans up slow or noisy edges. The 74HC123D can also be used for debouncing by generating a fixed pulse, but it requires external timing components and is generally selected for pulse generation rather than simple debouncing.