Part A
74ACT125SCX
onsemi
- Lifecycle
- Active
- Stock
- 6699 PCS
- Package
- SOIC-14
- Series
- Logic - Buffers, Drivers, Receivers, Transceivers
Replacement verdict
Compatible functional replacement candidate
The 74ACT125SCX and 74ACT125SJ are functionally equivalent quad bus buffer gates with 3-state outputs from the same 74ACT logic family, sharing identical logic function, drive capability, and supply voltage range. The primary distinction lies in package mounting type, which affects PCB assembly and thermal characteristics but does not alter electrical performance. Both devices are suitable for direct functional substitution where board layout accommodates the respective package footprints.
Logic Function
High match
Output Drive Current
High match
Supply Voltage Range
High match
Package Mounting Type
Validation required
Parts at a glance
Part B
74ACT125SJ
onsemi
- Lifecycle
- Active
- Stock
- 9273 PCS
- Package
- SOIC-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 | 74ACT125SCX | 74ACT125SJ | Why it matters |
|---|---|---|---|
| Package / Case | 14-SOIC (0.154", 3.90mm Width) | 14-SOP (0.209", 5.30mm Width) | Different package footprints require different PCB land patterns, so they are not drop-in replacements without layout changes. |
| Mounting Type | Surface Mount | Surface Mount | Both are surface mount, but the differing body widths affect board space and solder joint geometry. |
| Supplier Device Package | 14-SOIC | 14-SOP | The supplier package designation confirms the mechanical outline and must match the assembly footprint. |
| Packaging | Tape & Reel (TR) | Tube | Packaging affects automated assembly feeding and handling; tube parts are typically hand-loaded or used in low-volume runs. |
| Logic Type | Buffer, Non-Inverting | Buffer, Non-Inverting | Identical logic function ensures the same signal buffering behavior in the target circuit. |
| Number of Elements / Bits per Element | 4 / 1 | 4 / 1 | Matching channel count and width preserves the circuit's fan-out and signal routing requirements. |
| Output Type | 3-State | 3-State | Tri-state outputs are essential for bus sharing and must match to maintain the same enable/disable behavior. |
| Voltage - Supply | 4.5V ~ 5.5V | 4.5V ~ 5.5V | Identical supply range ensures compatibility with the same 5V logic power rail. |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C | Same temperature range means both parts can be used in the same environmental conditions. |
| Current - Output High, Low | 24mA, 24mA | 24mA, 24mA | Matching drive current ensures equivalent load driving capability and timing performance. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74ACT125SCX | 74ACT125SJ |
|---|---|---|
| Supplier | - | onsemi |
| 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) | -40°C ~ 85°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What is the difference between the 74ACT125SCX and the 74ACT125SJ?
The primary difference is the package type. The 74ACT125SCX is supplied in a 14-lead SOIC (Small Outline Integrated Circuit) package, while the 74ACT125SJ is supplied in a 14-lead SOP (Small Outline Package) or, depending on the manufacturer, a 14-lead SOIC with a different lead pitch or body width. Both devices are quad bus buffer gates with 3-state outputs from the 74ACT logic family.
Are the 74ACT125SCX and 74ACT125SJ electrically identical?
Yes, both devices share the same 74ACT125 die functionality: four independent non-inverting buffers with active-low output enable pins. They have identical DC and AC electrical characteristics as specified in the respective manufacturer datasheets, including propagation delay, input/output voltage thresholds, and drive current.
Can the 74ACT125SCX and 74ACT125SJ be used interchangeably in a PCB design?
No, they are not drop-in replacements because their package footprints differ. The 74ACT125SCX (SOIC) and 74ACT125SJ (SOP) have different body widths and lead pitches, requiring different PCB land patterns. Always verify the mechanical dimensions from the manufacturer datasheet before substituting.
What is the operating voltage range for both the 74ACT125SCX and 74ACT125SJ?
Both devices operate over a recommended supply voltage range of 4.5 V to 5.5 V, typical of the ACT logic family. They are not specified for 3.3 V operation and should not be used outside this range without validation.
Do the 74ACT125SCX and 74ACT125SJ have the same pinout?
Yes, both use the standard 14-pin 74ACT125 pinout: pins 1, 4, 10, and 13 are active-low output enables; pins 2, 5, 9, and 12 are inputs; pins 3, 6, 8, and 11 are outputs; pin 7 is GND; pin 14 is VCC. The pinout is identical despite the package difference.
Which package is more suitable for high-density PCB layouts?
The 74ACT125SCX in SOIC typically offers a smaller footprint than the 74ACT125SJ in SOP, depending on the specific manufacturer's SOP dimensions. SOIC is generally preferred for space-constrained designs, but always compare the exact package drawings from the datasheets.
Are the 74ACT125SCX and 74ACT125SJ RoHS compliant?
RoHS compliance depends on the specific manufacturer and ordering suffix. Many modern 74ACT125SCX and 74ACT125SJ parts are RoHS compliant, but this must be verified on the manufacturer's datasheet or product page. Do not assume compliance without confirmation.
What is the output drive current for the 74ACT125SCX and 74ACT125SJ?
Both devices typically provide ±24 mA output drive current at 5 V, as specified in the 74ACT125 datasheet. This is sufficient for driving moderate capacitive loads and standard TTL-compatible inputs.