Part A
74LCX125MTCX
onsemi
- Lifecycle
- Active
- Stock
- 6950 PCS
- Package
- TSSOP-14
- Series
- Lógica - Buffers, Drivers, Receivers, Transceivers
Replacement verdict
Not a drop-in replacement
The 74LCX125MTCX and 74LCX00TTR are not functionally interchangeable. The 74LCX125MTCX is a quad bus buffer with 3-state outputs, while the 74LCX00TTR is a quad 2-input NAND gate. Their logic functions, output configurations, and pinouts differ fundamentally, so neither device can directly substitute for the other in an existing design without circuit redesign.
Different logic function
Different output type
Different pinout
Different package
Parts at a glance
Part B
74LCX00TTR
STMicroeletrônica
- Lifecycle
- Active
- Stock
- 6012 PCS
- Series
- Lógica - Gates e Inverters
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 | 74LCX00TTR | Why it matters |
|---|---|---|---|
| Logic Function | Quad Buffer with 3-State Outputs | Quad 2-Input NAND Gate | The logic function defines the fundamental operation of the device; a buffer and a NAND gate are not functionally interchangeable in a circuit. |
| Output Type | 3-State | Push-Pull | 3-state outputs allow the device to be disconnected from a bus, while push-pull outputs cannot be tied together without contention. |
| Number of Inputs per Element | 1 | 2 | The input count determines the logic capability; a buffer has one input per channel while a NAND gate requires two inputs per gate. |
| Control Input | Output Enable (active LOW) | None | The presence of an enable pin allows bus sharing and power management, which is absent in the NAND gate. |
| Supply Voltage Range | 2.0 V to 3.6 V | 2.0 V to 3.6 V | Both devices operate over the same low-voltage range, making them compatible with 3.3 V logic systems. |
| Logic Family | LCX | LCX | Same logic family ensures similar input/output thresholds and noise margins. |
| Maximum Propagation Delay | 6.5 ns at 3.3 V | 6.5 ns at 3.3 V | Similar propagation delay means comparable speed performance in signal paths. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Identical temperature range ensures both parts can be used in the same environmental conditions. |
| Package Type | TSSOP-14 | TSSOP-14 | Same package and pin count allow for identical PCB footprint and assembly process. |
| Mounting Type | Surface Mount | Surface Mount | Both are surface-mount devices, suitable for modern automated assembly. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74LCX125MTCX | 74LCX00TTR |
|---|---|---|
| Supplier | - | STMicroelectronics |
| Series | 74LCX | 74LCX |
| Part Status | Active | Obsolete |
| Logic Type | Buffer, Non-Inverting | NAND Gate |
| Number of Circuits | - | 4 |
| Number of Inputs | - | 2 |
| Voltage - Supply | 2V ~ 3.6V | 2V ~ 3.6V |
| Current - Quiescent (Max) | - | 10 µA |
| Current - Output High Low | 24mA, 24mA | 24mA, 24mA |
| Logic Level - Low | - | 0.8V |
| Logic Level - High | - | 2V |
| Max Propagation Delay @ V Max CL | - | 4.3ns @ 3.3V, 50pF |
| Operating Temperature | -40°C ~ 85°C (TA) | -40°C ~ 85°C |
| 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 74LCX00TTR?
The 74LCX125MTCX is a quad non-inverting buffer/line driver with 3-state outputs, while the 74LCX00TTR is a quad 2-input NAND gate. The 74LCX125MTCX is designed for bus driving and signal buffering with high-impedance output capability, whereas the 74LCX00TTR performs logic NAND operations without 3-state output functionality.
Are the 74LCX125MTCX and 74LCX00TTR pin-to-pin compatible?
No. The 74LCX125MTCX and 74LCX00TTR have different pin functions and internal logic configurations. The 74LCX125MTCX includes output enable pins for each buffer, while the 74LCX00TTR has standard NAND gate inputs and outputs. They cannot be used interchangeably without circuit redesign.
What are the operating voltage ranges for these two devices?
Both the 74LCX125MTCX and 74LCX00TTR operate over a supply voltage range of 2.0 V to 3.6 V, typical of the LCX family. This makes them suitable for low-voltage 3.3 V and mixed 2.5 V/3.3 V logic systems.
What package types are used for the 74LCX125MTCX and 74LCX00TTR?
The 74LCX125MTCX is supplied in a TSSOP-14 package, while the 74LCX00TTR is supplied in a TSSOP-14 package as well. Both are surface-mount packages with 14 pins, but their pinouts differ due to different internal functions.
Can the 74LCX125MTCX drive heavier loads than the 74LCX00TTR?
Yes. The 74LCX125MTCX is specified with output drive capability of ±24 mA at 3.0 V, making it suitable for bus driving and line driving applications. The 74LCX00TTR has a lower output drive specification, typically ±24 mA as well, but its NAND gate configuration is not optimized for bus driving with 3-state control.
Do both devices support 5 V tolerant inputs?
Yes. Both the 74LCX125MTCX and 74LCX00TTR feature 5 V tolerant inputs when operated at VCC = 3.0 V to 3.6 V, allowing them to interface with 5 V logic systems without additional level shifting.
What is the propagation delay difference between the 74LCX125MTCX and 74LCX00TTR?
At 3.3 V, the 74LCX125MTCX typically exhibits a propagation delay of approximately 5.5 ns, while the 74LCX00TTR typically exhibits a propagation delay of approximately 5.0 ns. Both are fast enough for most high-speed logic applications, but the NAND gate is slightly faster due to simpler internal logic.
Which device is better for multiplexing or bus isolation applications?
The 74LCX125MTCX is better suited for multiplexing or bus isolation because it features 3-state outputs that can be placed in high-impedance mode, effectively disconnecting the output from the bus. The 74LCX00TTR lacks 3-state outputs and cannot provide bus isolation.