Part A
74ACT125SCX
Semi - conducteurs
- Lifecycle
- Active
- Stock
- 6699 PCS
- Package
- SOIC-14
- Series
- Logique - Buffers, lecteurs, récepteurs, émetteurs - récepteurs
Replacement verdict
Compatible functional replacement candidate
The 74ACT125SCX and 74ACT125MTR are functionally equivalent quad bus buffer gates with 3-state outputs, sharing identical logic function, pinout, and electrical characteristics. Both devices are drop-in replacement candidates for each other, with the primary distinction being package type and manufacturing source. Designers should verify package footprint compatibility and supply chain availability before substituting.
Logic Function
High match
Pin Configuration
High match
Package Type
Validation required
Electrical Characteristics
High match
Parts at a glance
Part B
74ACT125MTR
Semi - conducteurs optiques
- Lifecycle
- Active
- Stock
- 5028 PCS
- Package
- SOIC-14
- 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 | 74ACT125SCX | 74ACT125MTR | Why it matters |
|---|---|---|---|
| Manufacturer | onsemi (Fairchild) | STMicroelectronics | Different manufacturers may have subtle differences in process, documentation, and second-source qualification requirements. |
| Logic Family | ACT (Advanced CMOS with TTL-compatible inputs) | ACT (Advanced CMOS with TTL-compatible inputs) | Same logic family ensures compatible input thresholds, output drive, and switching behavior for direct substitution. |
| Function | Quad bus buffer with 3-state outputs | Quad bus buffer with 3-state outputs | Identical logic function is required for functional substitutability in a given circuit. |
| Number of Channels | 4 | 4 | Channel count must match to preserve the bus width and pinout functionality. |
| Output Type | 3-state (tri-state) | 3-state (tri-state) | Tri-state outputs allow bus sharing; a non-tri-state device would not be a functional substitute. |
| Supply Voltage Range | 4.5 V to 5.5 V | 4.5 V to 5.5 V | Operating voltage range must overlap with the system supply to ensure reliable operation. |
| Output Drive Current | ±24 mA | ±24 mA | Drive current determines fan-out and ability to drive loads; matching values preserve signal integrity. |
| Propagation Delay | ~8 ns (typical at 5 V) | ~8 ns (typical at 5 V) | Similar propagation delay ensures timing margins are maintained when substituting parts. |
| Package Type | SOIC-14 | SOIC-14 | Same package footprint allows drop-in replacement without PCB redesign. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range must cover the application environment for reliable operation. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74ACT125SCX | 74ACT125MTR |
|---|---|---|
| Supplier | - | STMicroelectronics |
| Series | 74ACT | 74ACT |
| Part Status | Obsolete | Obsolete |
| Logic Type | Buffer, Non-Inverting | Buffer, Non-Inverting |
| Number of Elements | 4 | 4 |
| Number of Bits per Element | 1 | 1 |
| Output Type | 3-State | 3-State |
| Current - Output High Low | 24mA, 24mA | 24mA, 24mA |
| Voltage - Supply | 4.5V ~ 5.5V | 4.5V ~ 5.5V |
| Operating Temperature | -40°C ~ 85°C (TA) | -55°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the 74ACT125SCX and 74ACT125MTR?
Both are quad bus buffer gates with 3-state outputs from the 74ACT logic family. The 74ACT125SCX is supplied by onsemi (formerly Fairchild) in a 14-lead SOIC package, while the 74ACT125MTR is supplied by STMicroelectronics in a 14-lead SOIC package. Both devices provide four independent non-inverting buffers with active-low output enable pins.
Are the 74ACT125SCX and 74ACT125MTR functionally interchangeable?
Yes. Both devices implement the same 74ACT125 logic function: four independent non-inverting 3-state buffers with active-low enable inputs. They share the same pinout and the same 14-lead SOIC package footprint, so they are functionally and pin-compatible in most designs.
What are the key electrical specifications common to both devices?
Both are 74ACT-series devices operating from a 4.5 V to 5.5 V supply with TTL-compatible inputs. They feature typical propagation delay of approximately 6 ns to 8 ns at 5 V, 3-state outputs, and balanced output drive of ±24 mA. Exact limits should be confirmed against the respective manufacturer datasheets.
Do the 74ACT125SCX and 74ACT125MTR differ in operating temperature range?
Both devices are specified for the industrial temperature range of −40 °C to +85 °C. Designers should verify the exact temperature grade on the specific manufacturer datasheet, as some variants may be offered in extended ranges.
What package and pin configuration do these devices use?
Both the 74ACT125SCX and 74ACT125MTR are offered in a 14-lead SOIC (Small Outline Integrated Circuit) package with 1.27 mm pitch. The pinout follows the standard 74ACT125 configuration: four buffer inputs, four buffer outputs, four active-low enable pins, VCC, and GND.
Can the 74ACT125SCX and 74ACT125MTR be used in mixed 5 V and 3.3 V systems?
These are 5 V 74ACT devices with TTL-compatible input thresholds, which allows them to accept 3.3 V logic signals at their inputs when powered from 5 V. However, their outputs swing to the 5 V supply rail, so level shifting may be required when driving 3.3 V-only inputs.
Which manufacturer produces each part number?
The 74ACT125SCX is manufactured by onsemi (originally Fairchild Semiconductor). The 74ACT125MTR is manufactured by STMicroelectronics. Both are standard 74ACT125 quad bus buffer products available through authorized distributors such as DigiKey, Mouser, and TTI.
What is the difference between the SCX and MTR suffixes?
The suffixes are manufacturer-specific ordering codes. "SCX" is onsemi's tape-and-reel SOIC designation, while "MTR" is STMicroelectronics' tape-and-reel SOIC designation. The core electrical function and package type are equivalent; only the manufacturer, marking, and packaging logistics differ.