Part A
74LCX04MTCX
Semi - conducteurs
- Lifecycle
- Active
- Stock
- 4842 PCS
- Package
- TSSOP-14
- Series
- Logique - portes et Onduleurs
Replacement verdict
Not a drop-in replacement
The 74LCX04MTCX and 74LCX240TTR are not functionally interchangeable. The 74LCX04MTCX is a hex inverter with six independent NOT gates, while the 74LCX240TTR is an octal buffer/line driver with 3-state outputs arranged as two 4-bit groups with separate output-enable controls. Although both devices share the LCX low-voltage CMOS family and similar TSSOP package formats, their logic functions, channel counts, pinouts, and output configurations differ fundamentally, making direct substitution impossible without circuit redesign.
Different logic function
Different channel count
Different output type
Different pinout
Parts at a glance
Part B
74LCX240TTR
Semi - conducteurs optiques
- Lifecycle
- Active
- Stock
- 4104 PCS
- Package
- TSSOP-20
- Series
- Logique - Buffers, lecteurs, récepteurs, émetteurs - récepteurs
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74LCX04MTCX | 74LCX240TTR | Why it matters |
|---|---|---|---|
| Logic Function | Hex Inverter | Octal Buffer/Line Driver with 3-State Outputs (Inverting) | The logic function determines the fundamental signal operation; these parts perform different functions and are not direct substitutes. |
| Number of Circuits / Channels | 6 | 8 | Channel count affects how many independent signal lines can be processed, impacting board layout and design capacity. |
| Output Type | Push-Pull | 3-State | 3-state outputs allow bus sharing and high-impedance disconnection, while push-pull outputs cannot be tied together on a shared bus. |
| Package / Case | 14-TSSOP | 20-TSSOP | Package footprint and pin count must match the PCB layout; different packages are not drop-in compatible. |
| Number of Pins | 14 | 20 | Pin count determines the physical and electrical interface; mismatched pin counts prevent direct substitution. |
| Supply Voltage Range | 2.0 V to 3.6 V | 2.0 V to 3.6 V | Both operate over the same low-voltage range, ensuring compatibility with 3.3 V and lower-voltage logic systems. |
| Logic Family | LCX | LCX | Same logic family ensures compatible input/output thresholds and switching characteristics. |
| Output Drive Current (IOH/IOL) | ±24 mA | ±24 mA | Matching drive current means both can drive similar loads, which is important for signal integrity and fan-out. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Identical temperature ratings ensure both parts work in the same environmental conditions. |
| Propagation Delay (tPD) | 5.2 ns (max at 3.3 V) | 6.5 ns (max at 3.3 V) | Propagation delay affects timing margins; a slower part may violate setup/hold requirements in high-speed designs. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74LCX04MTCX | 74LCX240TTR |
|---|---|---|
| Supplier | - | STMicroelectronics |
| Series | 74LCX | 74LCX |
| Part Status | Active | Obsolete |
| Logic Type | Inverter | Buffer, Inverting |
| Number of Elements | - | 2 |
| Number of Bits per Element | - | 4 |
| Output Type | - | 3-State |
| Current - Output High Low | 24mA, 24mA | 24mA, 24mA |
| Voltage - Supply | 2V ~ 3.6V | 2V ~ 3.6V |
| Operating Temperature | -40°C ~ 85°C | -55°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Number of Circuits | 6 | - |
| Number of Inputs | 1 | - |
| Current - Quiescent (Max) | 10 µA | - |
| Logic Level - Low | 0.7V ~ 0.8V | - |
| Logic Level - High | 1.7V ~ 2V | - |
| Max Propagation Delay @ V Max CL | 5.2ns @ 3.3V, 50pF | - |
Frequently asked questions
What are the primary functional differences between the 74LCX04MTCX and the 74LCX240TTR?
The 74LCX04MTCX is a hex inverter, providing six independent NOT gates that invert a single logic signal. The 74LCX240TTR is an octal buffer/line driver with 3-state outputs, providing eight non-inverting buffers with dual enable pins for bus-oriented applications.
Are the 74LCX04MTCX and 74LCX240TTR pin-to-pin compatible?
No. The 74LCX04MTCX is typically offered in a 14-pin TSSOP package, while the 74LCX240TTR is typically offered in a 20-pin TSSOP package. They have different pin counts, pinouts, and functions, so they are not drop-in replacements.
Can the 74LCX04MTCX and 74LCX240TTR operate from the same supply voltage?
Yes. Both devices are part of the LCX family and are specified for a nominal 3.3 V supply, with an operating range typically from 2.0 V to 3.6 V. However, always verify the exact recommended operating conditions in the respective manufacturer datasheets.
Does the 74LCX240TTR have 3-state outputs while the 74LCX04MTCX does not?
Yes. The 74LCX240TTR features 3-state outputs controlled by two active-low output enable pins, allowing the outputs to be placed in a high-impedance state for bus sharing. The 74LCX04MTCX has standard push-pull outputs with no high-impedance state.
What is the logic function of each device?
The 74LCX04MTCX performs logical inversion (Y = A̅) on six independent channels. The 74LCX240TTR performs non-inverting buffering (Y = A) on eight channels, with the additional ability to disable all outputs via the enable pins.
Are both devices suitable for level-shifting applications?
Both devices can be used in mixed-voltage systems when operated within their specified supply and input voltage ranges. The 74LCX04MTCX and 74LCX240TTR both have 5 V tolerant inputs, which allows them to accept 5 V logic signals while operating at 3.3 V. Verify the exact input voltage ratings in the manufacturer datasheet before use.
Which device is better for driving a shared data bus?
The 74LCX240TTR is better suited for shared data bus applications because its 3-state outputs can be disabled to present a high-impedance state, preventing bus contention. The 74LCX04MTCX lacks 3-state outputs and is not intended for direct bus multiplexing.
Do both devices have the same output drive current capability?
Both devices are typically specified with similar output drive characteristics within the LCX family, often around ±24 mA at 3.0 V. However, exact drive currents, propagation delays, and capacitive load ratings may differ between the two parts. Always consult the specific manufacturer datasheet for the 74LCX04MTCX and 74LCX240TTR to confirm the guaranteed specifications.