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 74VHC595SJ are not functionally interchangeable. The 74VHC14MX is a hex Schmitt-trigger inverter intended for signal conditioning and waveform shaping, while the 74VHC595SJ is an 8-bit serial-in/parallel-out shift register with output latches designed for serial-to-parallel data conversion and LED or relay driving. Their internal logic functions, pin configurations, and application roles are fundamentally different, so neither device can directly substitute for the other in an existing design.
Different logic function
Different pinout
Different input type
Different output type
Parts at a glance
Part B
74VHC595SJ
onsemi
- Lifecycle
- Active
- Stock
- 8887 PCS
- Package
- SOIC-16
- Series
- Logic - Shift Registers
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 | 74VHC595SJ | Why it matters |
|---|---|---|---|
| Logic Function | Hex Schmitt-Trigger Inverter | 8-Bit Serial-In/Serial-Out Shift Register with Output Latches | The core function determines whether the parts can be substituted at all; these devices perform completely different logic operations. |
| Number of Circuits / Bits | 6 inverters | 8-bit shift register | Channel/bit count affects how many signals can be processed and the required board footprint. |
| Output Type | Push-pull (standard CMOS) | Tri-state (3-state) with serial output | Tri-state outputs allow bus sharing, while push-pull outputs cannot be tied together; this impacts system architecture. |
| Input Type | Schmitt-trigger inputs | Standard CMOS inputs | Schmitt-trigger inputs provide hysteresis for noise immunity and slow-edge signals, which standard inputs lack. |
| Propagation Delay (typical) | ~5.5 ns at 5 V | ~6.5 ns at 5 V (clock to output) | Timing affects maximum operating frequency and signal integrity in high-speed designs. |
| Supply Voltage Range | 2.0 V to 5.5 V | 2.0 V to 5.5 V | Both support the same VHC voltage range, allowing operation in 3.3 V and 5 V systems. |
| Package | SOIC-14 | SOIC-16 | Different pin counts and package sizes mean they are not drop-in footprint compatible. |
| Pin Count | 14 | 16 | Pin count determines PCB layout compatibility and available I/O. |
| Operating Temperature Range | -40°C to +85°C | -40°C to +85°C | Both meet industrial temperature requirements, suitable for the same environmental conditions. |
| Output Drive Current | ±8 mA at 5 V | ±8 mA at 5 V | Drive strength determines fan-out and ability to drive LEDs or other loads directly. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74VHC14MX | 74VHC595SJ |
|---|---|---|
| Supplier | - | onsemi |
| Series | 74VHC | 74VHC |
| Part Status | Active | Obsolete |
| Logic Type | Inverter | Shift Register |
| Output Type | - | Tri-State |
| Number of Elements | - | 1 |
| Number of Bits per Element | - | 8 |
| Function | - | Serial to Parallel, Serial |
| Voltage - Supply | 2V ~ 5.5V | 2V ~ 5.5V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
| Number of Circuits | 6 | - |
| Number of Inputs | 1 | - |
| Features | Schmitt Trigger | - |
| 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 | - |
Frequently asked questions
What are the primary functions of the 74VHC14MX and 74VHC595SJ?
The 74VHC14MX is a hex Schmitt-trigger inverter, providing six independent inverter gates with hysteresis on the inputs. The 74VHC595SJ is an 8-bit serial-in, parallel-out shift register with a storage register and 3-state output registers.
Can the 74VHC14MX and 74VHC595SJ be used interchangeably in a design?
No. They perform fundamentally different logic functions. The 74VHC14MX inverts and conditions signals with Schmitt-trigger hysteresis, while the 74VHC595SJ performs serial-to-parallel data conversion with latching and 3-state outputs. They are not pin-compatible or functionally equivalent.
What are the package types for the 74VHC14MX and 74VHC595SJ?
The 74VHC14MX is typically offered in a 14-pin SOIC package. The 74VHC595SJ is typically offered in a 16-pin SOIC package. Package dimensions and pin counts differ, so PCB land patterns are not interchangeable.
What is the operating voltage range for both devices?
Both the 74VHC14MX and 74VHC595SJ are members of the VHC family and operate over a supply voltage range of 2.0 V to 5.5 V, with typical operation at 3.3 V or 5 V.
Do both devices have Schmitt-trigger inputs?
Only the 74VHC14MX has Schmitt-trigger inputs on all six inverter channels. The 74VHC595SJ does not have Schmitt-trigger inputs; its inputs are standard CMOS-level inputs without specified hysteresis.
What are the output drive capabilities of the 74VHC14MX and 74VHC595SJ?
Both devices provide standard VHC-family output drive, typically ±8 mA at 5 V VCC. The 74VHC595SJ outputs are 3-state and can be placed in high-impedance mode, while the 74VHC14MX outputs are always active push-pull.
Which device is suitable for signal debouncing or waveform shaping?
The 74VHC14MX is suitable for signal debouncing and waveform shaping due to its Schmitt-trigger inputs, which provide hysteresis and improve noise immunity on slow or noisy input signals. The 74VHC595SJ is not intended for this function.
Which device is used for expanding output pins in a microcontroller design?
The 74VHC595SJ is used to expand output pins by converting serial data from a microcontroller into 8 parallel outputs with latching and 3-state control. The 74VHC14MX does not provide serial-to-parallel conversion or output expansion.