Part A
74LCX244MTC
onsemi
- Lifecycle
- Active
- Stock
- 5042 PCS
- Series
- Lógica - Buffers, Drivers, Receivers, Transceivers
Replacement verdict
Not a drop-in replacement
The 74LCX244MTC and 74LCX125TTR are not functionally interchangeable. The 74LCX244MTC is a dual 4-bit non-inverting buffer with 3-state outputs, while the 74LCX125TTR is a quad single-bit non-inverting buffer with 3-state outputs. Although both share LCX-family low-voltage CMOS characteristics, differences in channel configuration, output enable logic, pinout, and package footprint prevent direct substitution without circuit redesign.
Different channel configuration
Different output enable logic
Different pinout
Different package footprint
Parts at a glance
Part B
74LCX125TTR
STMicroeletrônica
- Lifecycle
- Active
- Stock
- 2186 PCS
- Package
- TSSOP-14
- Series
- Lógica - 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 | 74LCX244MTC | 74LCX125TTR | Why it matters |
|---|---|---|---|
| Logic Function | Octal Buffer/Line Driver with 3-State Outputs | Quad Bus Buffer with 3-State Outputs | Determines the number of channels and direction of signal flow; the 244 has 8 buffers while the 125 has 4, so they are not pin-compatible substitutes. |
| Number of Channels | 8 | 4 | Channel count dictates how many independent signal lines can be buffered, directly affecting board layout and functionality. |
| Output Enable Control | Two active-low OE pins (one per 4-bit group) | Four independent active-low OE pins (one per channel) | Different enable architectures affect how outputs are tri-stated and how the device is controlled in a bus system. |
| Directionality | Unidirectional (A to Y) | Unidirectional (A to Y) | Both are unidirectional buffers, but the 244 groups channels under shared enables while the 125 provides per-channel control. |
| Package / Mounting | 20-TSSOP (0.173", 4.40mm Width) | 14-TSSOP (0.173", 4.40mm Width) | Different pin counts and package sizes mean the two parts are not drop-in replacements on the same PCB footprint. |
| 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, supporting 3.3 V and mixed 2.5 V logic systems. |
| Output Drive Current | ±24 mA | ±24 mA | Identical drive strength means both can drive similar loads, but channel count still differs. |
| Propagation Delay (tpd) | 6.5 ns max at 3.3 V | 6.5 ns max at 3.3 V | Similar timing performance ensures comparable signal integrity in high-speed bus applications. |
| Operating Temperature Range | -40°C to +85°C | -40°C to +85°C | Matching industrial temperature ranges allow use in similar environmental conditions. |
| Pin Count | 20 | 14 | Pin count difference prevents direct substitution without PCB redesign. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74LCX244MTC | 74LCX125TTR |
|---|---|---|
| Supplier | - | STMicroelectronics |
| Series | 74LCX | 74LCX |
| Part Status | Active | Obsolete |
| Logic Type | Buffer, Non-Inverting | Buffer, Non-Inverting |
| Number of Elements | 2 | 4 |
| Number of Bits per Element | 4 | 1 |
| Output Type | 3-State | 3-State |
| Current - Output High Low | - | 24mA, 24mA |
| Voltage - Supply | 2V ~ 3.6V | 2V ~ 3.6V |
| Operating Temperature | -40°C ~ 85°C (TA) | -40°C ~ 85°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Base Product Number | 74LCX244 | - |
| Current - Output High, Low | 24mA, 24mA | - |
| Packaging | Tube | - |
Frequently asked questions
What are the main functional differences between the 74LCX244MTC and the 74LCX125TTR?
The 74LCX244MTC is an octal buffer/line driver with 3-state outputs, organized as two 4-bit groups controlled by two separate output-enable pins (1OE and 2OE). The 74LCX125TTR is a quad buffer/line driver with 3-state outputs, where each of the four buffers has its own independent output-enable pin (1OE through 4OE). The 74LCX244MTC provides eight buffers with two enable controls, while the 74LCX125TTR provides four buffers with four independent enable controls.
Are the 74LCX244MTC and 74LCX125TTR pin-to-pin compatible?
No. The 74LCX244MTC is supplied in a 20-pin TSSOP package (MTC suffix), while the 74LCX125TTR is supplied in a 14-pin TSSOP package (TTR suffix). They have different pin counts, different pinouts, and different package footprints, so they are not drop-in replacements for each other.
What is the operating voltage range for both devices?
Both the 74LCX244MTC and the 74LCX125TTR are LCX-family CMOS devices designed for 2.0 V to 3.6 V VCC operation, with 5 V tolerant inputs and outputs. This allows them to interface between 3.3 V logic and 5 V systems without additional level shifting.
Can the 74LCX244MTC drive higher total current than the 74LCX125TTR?
Both devices specify ±24 mA output drive at VCC = 3.0 V per output. However, because the 74LCX244MTC has eight outputs and the 74LCX125TTR has four outputs, the 74LCX244MTC can sink or source more total current across the device when all outputs are active. The absolute maximum total current per device and per VCC/GND pin must be verified in the respective manufacturer datasheets.
How do the output-enable controls differ between the two parts?
On the 74LCX244MTC, outputs are organized in two 4-bit groups: 1OE controls outputs 1Y0–1Y3 and 2OE controls outputs 2Y0–2Y3. On the 74LCX125TTR, each buffer has its own active-low output-enable pin (1OE, 2OE, 3OE, 4OE), allowing independent 3-state control of each of the four buffers. This makes the 74LCX125TTR more flexible for individually gating signals, while the 74LCX244MTC is suited for bus-oriented applications with grouped enables.
Which device is more suitable for a bidirectional bus application?
Neither device is inherently bidirectional; both are unidirectional buffers. The 74LCX244MTC is commonly used for unidirectional bus driving with grouped 3-state control, while the 74LCX125TTR is used for unidirectional signal buffering with independent per-channel enables. For true bidirectional bus applications, a dedicated transceiver such as a 74LCX245 would typically be required.
Do both devices support 5 V tolerant inputs and outputs?
Yes. Both the 74LCX244MTC and the 74LCX125TTR are specified with 5 V tolerant inputs and outputs, which allows them to be used in mixed 3.3 V and 5 V systems. This is a standard feature of the LCX logic family.
What are the typical propagation delay and operating temperature specifications for these devices?
Both devices are specified with a typical propagation delay (tPD) of approximately 6.5 ns at VCC = 3.0 V and an operating temperature range of –40 °C to +85 °C. Exact limits and test conditions should be confirmed in the respective manufacturer datasheets, as values may vary slightly between suppliers.