Part A
74AC245SCX
onsemi
- Lifecycle
- Active
- Stock
- 5851 PCS
- Package
- SOIC-20
- Series
- Logic - Buffers, Drivers, Receivers, Transceivers
Replacement verdict
Not a drop-in replacement
The 74AC245SCX and 74AC241MTCX are not functionally interchangeable. Although both are octal bus transceivers from the AC family, they differ in control architecture, output enable polarity, pinout, and package footprint, requiring design changes before substitution.
Different control logic
Different enable polarity
Different pinout
Different package footprint
Parts at a glance
Part B
74AC241MTCX
onsemi
- Lifecycle
- Active
- Stock
- 4225 PCS
- Package
- TSSOP-20
- 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 | 74AC245SCX | 74AC241MTCX | Why it matters |
|---|---|---|---|
| Logic Function | Octal Bus Transceiver, Non-Inverting, 3-State | Octal Buffer/Line Driver, Non-Inverting, 3-State | Determines the core signal-flow behavior; a transceiver supports bidirectional data transfer while a buffer/driver is unidirectional, so they are not directly substitutable in most designs. |
| Direction Control | Direction pin (DIR) selects A-to-B or B-to-A | Two output-enable pins (1OE, 2OE) control two 4-bit groups | The control scheme dictates how the device is enabled and which way data flows, affecting PCB routing and firmware/control logic. |
| Number of Bits | 8 (single 8-bit port pair) | 8 (two 4-bit groups) | Although both handle 8 bits, the 74AC241 splits them into two independently enabled 4-bit halves, which changes how partial-bus control can be implemented. |
| Package / Mounting | SOIC-20 (surface mount) | TSSOP-20 (surface mount) | Different package footprints require different PCB land patterns, so they are not drop-in replacements without a layout change. |
| Supply Voltage Range | 2.0 V to 6.0 V | 2.0 V to 6.0 V | Both support the AC family's wide 2 V–6 V range, allowing use in 3.3 V and 5 V systems; identical here, so no compatibility concern. |
| Output Drive Current | ±24 mA (at 5 V) | ±24 mA (at 5 V) | Drive strength affects fan-out and trace driving capability; matching values mean similar load-driving performance. |
| Propagation Delay | ~5.5 ns typical (at 5 V) | ~5.5 ns typical (at 5 V) | Timing determines maximum operating frequency and setup/hold margins; equivalent delays mean similar speed performance. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Industrial temperature range ensures reliable operation in harsh environments; identical ratings mean equal environmental suitability. |
| Pin Count | 20 | 20 | Same pin count but different pinout assignments, so the devices are not pin-to-pin compatible despite matching package sizes. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74AC245SCX | 74AC241MTCX |
|---|---|---|
| Supplier | - | onsemi |
| Series | 74AC | 74AC |
| Part Status | Active | Obsolete |
| Logic Type | Transceiver, Non-Inverting | Buffer, Non-Inverting |
| Number of Elements | 1 | 2 |
| Number of Bits per Element | 8 | 4 |
| Output Type | 3-State | 3-State |
| Current - Output High Low | 24mA, 24mA | 24mA, 24mA |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 85°C (TA) | -40°C ~ 85°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the primary functional differences between the 74AC245SCX and the 74AC241MTCX?
The 74AC245SCX is an octal bus transceiver with non-inverting 3-state outputs, designed for bidirectional asynchronous communication between data buses. The 74AC241MTCX is an octal buffer/line driver with non-inverting 3-state outputs, featuring a dual enable structure that allows independent control of two 4-bit groups. The 74AC245SCX provides a direction control pin (DIR) for bidirectional data flow, while the 74AC241MTCX is unidirectional with two separate output enable pins (1OE and 2OE).
Are the 74AC245SCX and 74AC241MTCX pin-to-pin compatible?
No. The 74AC245SCX is typically supplied in a 20-pin SOIC package (SCX suffix) with a pinout that includes a direction pin (DIR) and an output enable (OE). The 74AC241MTCX is supplied in a 20-pin TSSOP package (MTCX suffix) with a different pinout that includes two output enable pins (1OE, 2OE) and no direction pin. The pin functions and package footprints differ, so they are not direct drop-in replacements.
Can the 74AC245SCX be used as a unidirectional buffer like the 74AC241MTCX?
Yes, the 74AC245SCX can be configured for unidirectional operation by tying the DIR pin to a fixed logic level (high or low) to select one direction and using the OE pin to enable or disable the outputs. However, the 74AC241MTCX offers independent control of two 4-bit groups via separate output enable pins, which the 74AC245SCX does not provide.
What are the operating voltage and logic family specifications for these devices?
Both the 74AC245SCX and 74AC241MTCX are members of the AC (Advanced CMOS) logic family. They are specified for operation over a recommended supply voltage range of 2.0 V to 6.0 V, with typical operation at 5.0 V. Both devices feature balanced propagation delays and are characterized for operation from -40°C to +85°C (industrial temperature range) depending on the specific manufacturer suffix.
What is the difference in output drive current between the 74AC245SCX and 74AC241MTCX?
Both devices typically provide ±24 mA output drive current at 5.0 V VCC, as per the AC logic family standard. This allows them to drive heavily loaded buses or transmission lines. The drive strength is essentially identical between the two devices when compared under the same voltage and temperature conditions.
Which device is better suited for bidirectional bus applications?
The 74AC245SCX is specifically designed for bidirectional bus applications due to its direction control (DIR) pin and single output enable (OE), which allow the device to transmit data from A to B or B to A. The 74AC241MTCX is unidirectional and is better suited for buffering or driving signals in one direction, such as address or control lines, where independent enable control of two 4-bit groups is beneficial.
Are the 74AC245SCX and 74AC241MTCX available in the same package types?
No. The 74AC245SCX is commonly available in a 20-pin SOIC package (as indicated by the SCX suffix). The 74AC241MTCX is commonly available in a 20-pin TSSOP package (as indicated by the MTCX suffix). Package options may vary by manufacturer, but the specific suffixes denote different package families, so they are not interchangeable without PCB layout changes.
What are the typical propagation delay and input capacitance for these devices?
For both the 74AC245SCX and 74AC241MTCX, typical propagation delay (tPD) is approximately 5.5 ns at 5.0 V VCC and 25°C. Typical input capacitance (CI) is 4.5 pF, and typical output capacitance (CO) is 12 pF for both devices. These values are consistent with the AC logic family characteristics and are verified in manufacturer datasheets.