Part A
74LCX04MTCX
onsemi
- Lifecycle
- Active
- Stock
- 4842 PCS
- Package
- TSSOP-14
- Series
- Logic - Gates and Inverters
Replacement verdict
Not a drop-in replacement
The 74LCX125MTCX and 74LCX04MTCX are not functionally interchangeable despite sharing the same LCX logic family and TSSOP-14 package. The 74LCX125MTCX is a quad bus buffer with 3-state outputs and active-low output enable controls, while the 74LCX04MTCX is a hex inverter with standard push-pull outputs. The differences in logic function, channel count, output stage configuration, and control pin architecture make direct substitution impossible without circuit redesign.
Different logic function
Different channel count
Different output type
Different control architecture
Parts at a glance
Part B
74LCX125MTCX
onsemi
- Lifecycle
- Active
- Stock
- 6950 PCS
- Package
- TSSOP-14
- Series
- Logic - Buffers, Drivers, Receivers, Transceivers
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74LCX125MTCX | 74LCX04MTCX | Why it matters |
|---|---|---|---|
| Logic Function | Quad Buffer with 3-State Outputs | Hex Inverter | Defines the fundamental logic operation; a buffer passes signals with high impedance control, while an inverter provides logical negation, making them non-interchangeable in function. |
| Number of Circuits | 4 | 6 | Determines how many independent signal channels are available; a different channel count affects board layout and whether the part can replace another in a given design. |
| Output Type | 3-State | Push-Pull | 3-state outputs allow bus sharing by entering high impedance, while push-pull outputs always drive high or low; this affects bus contention and multi-driver configurations. |
| Control Input | Output Enable (active low) | None | The presence of an enable pin allows the buffer to be disconnected from the bus, a feature absent in the inverter, which impacts system control and power management. |
| Supply Voltage Range | 2.0 V to 3.6 V | 2.0 V to 3.6 V | Both parts operate over the same low-voltage range, ensuring compatibility with 3.3 V and lower logic systems. |
| Propagation Delay (tpd) | 6.5 ns (max at 3.3 V) | 6.5 ns (max at 3.3 V) | Similar propagation delay means comparable speed performance, which is critical for timing-sensitive applications. |
| Output Drive Current (IOL/IOH) | ±24 mA | ±24 mA | Matching drive strength ensures both parts can drive similar loads without additional buffering. |
| Package Type | TSSOP-14 | TSSOP-14 | Identical package and pin count simplify PCB footprint compatibility, though pin functions differ. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Same temperature range ensures both parts are suitable for industrial and commercial environments. |
| Input Voltage Tolerance | 5 V tolerant inputs | 5 V tolerant inputs | 5 V tolerance allows safe interfacing with higher-voltage logic without damage, a key feature for mixed-voltage systems. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74LCX04MTCX | 74LCX125MTCX |
|---|---|---|
| Series | 74LCX | 74LCX |
| Part Status | Active | Active |
| Logic Type | Inverter | Buffer, Non-Inverting |
| Number of Circuits | 6 | - |
| Number of Inputs | 1 | - |
| Voltage - Supply | 2V ~ 3.6V | 2V ~ 3.6V |
| Current - Quiescent (Max) | 10 µA | - |
| Current - Output High Low | 24mA, 24mA | 24mA, 24mA |
| Logic Level - Low | 0.7V ~ 0.8V | - |
| Logic Level - High | 1.7V ~ 2V | - |
| Max Propagation Delay @ V Max CL | 5.2ns @ 3.3V, 50pF | - |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Number of Elements | - | 4 |
| Number of Bits per Element | - | 1 |
| Output Type | - | 3-State |
Frequently asked questions
What are the primary functional differences between the 74LCX125MTCX and the 74LCX04MTCX?
The 74LCX125MTCX is a quad buffer/line driver with 3-state outputs, while the 74LCX04MTCX is a hex inverter. The 74LCX125MTCX provides four independent non-inverting buffers with tri-state control pins, whereas the 74LCX04MTCX provides six independent inverting gates without tri-state capability.
Are the 74LCX125MTCX and 74LCX04MTCX pin-to-pin compatible?
No. Both devices are offered in the TSSOP-14 package (MTC suffix), but their pin functions differ. The 74LCX125MTCX uses pins for four data inputs, four data outputs, and two output-enable pins, while the 74LCX04MTCX uses all 14 pins for six inverter inputs and six inverter outputs plus power and ground. They cannot be interchanged without circuit redesign.
What is the operating voltage range for both the 74LCX125MTCX and 74LCX04MTCX?
Both devices operate over a supply voltage range of 2.0 V to 3.6 V, with typical operation at 3.3 V. They are designed for low-voltage CMOS logic applications and are not specified for 5 V supply operation, though inputs may be 5 V tolerant depending on the manufacturer's datasheet.
Can the 74LCX125MTCX and 74LCX04MTCX be used in mixed-voltage systems?
Yes, both devices feature 5 V tolerant inputs and outputs when operated at VCC = 3.0 V to 3.6 V, allowing interfacing with 5 V logic systems. However, the 74LCX125MTCX 3-state outputs can be placed in high-impedance mode, which is useful for bus sharing, while the 74LCX04MTCX outputs are always active.
What are the output drive capabilities of the 74LCX125MTCX and 74LCX04MTCX?
Both devices typically provide ±24 mA output drive at 3.0 V VCC, making them suitable for driving moderate capacitive loads and bus lines. The 74LCX125MTCX 3-state outputs can drive buses directly, while the 74LCX04MTCX is intended for signal inversion and buffering in point-to-point applications.
Which device is better suited for bus-oriented applications?
The 74LCX125MTCX is better suited for bus-oriented applications because its 3-state outputs allow multiple devices to share a common bus by placing outputs in high-impedance mode when not enabled. The 74LCX04MTCX lacks 3-state outputs and cannot be directly connected to a shared bus without external isolation.
Do both the 74LCX125MTCX and 74LCX04MTCX support live insertion?
Yes, both devices are designed to support live insertion and removal without damaging the device or disrupting the bus, provided the recommended power-up and power-down sequencing and current-limiting precautions specified in the manufacturer datasheet are followed.
What are the typical propagation delays for the 74LCX125MTCX and 74LCX04MTCX?
At VCC = 3.3 V and 25°C, both devices typically exhibit propagation delays in the range of approximately 3.5 ns to 6.5 ns, depending on load conditions and the specific manufacturer. The 74LCX04MTCX inverter and 74LCX125MTCX buffer have comparable speed characteristics within the LCX family.