Part A
74LCX244MTC
オンセミコンダクター社
- Lifecycle
- Active
- Stock
- 5042 個数
- Series
- ロジック - バッファ、ドライバ、レシーバ、トランシーバ
Replacement verdict
Compatible functional replacement candidate
The 74LCX244MTC and 74LCX245TTR are functionally compatible octal buffer/transceiver devices sharing the same LCX logic family, 20-pin TSSOP footprint, and 2.3 V to 3.6 V operating range. The primary distinction is the 74LCX244's unidirectional dual 4-bit buffer configuration versus the 74LCX245's bidirectional 8-bit transceiver with direction control, making the 74LCX245 a viable substitute only where bidirectional data flow is not required or can be externally managed.
Logic Function
High match
Direction Control
Validation required
Package Type
High match
Supply Voltage
High match
Parts at a glance
Part B
74LCX245TTR
RFE/フューゼテック
- Lifecycle
- Active
- Stock
- 3964 個数
- Package
- TSSOP-20
- Series
- ロジック - バッファ、ドライバ、レシーバ、トランシーバ
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 | 74LCX245TTR | Why it matters |
|---|---|---|---|
| Logic Function | Octal Buffer/Line Driver (non-inverting, unidirectional) | Octal Bus Transceiver (non-inverting, bidirectional) | Determines whether the device can drive signals in one direction only (244) or both directions (245), which is critical for bus-oriented designs. |
| Direction Control | Two active-low output enables (1OE, 2OE) | One direction pin (DIR) plus one active-low output enable (OE) | The 245 supports bidirectional data flow via DIR, while the 244 only enables/disables outputs, so they are not directly interchangeable in bus applications. |
| 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, allowing use in 2.5 V and 3.3 V systems. |
| Logic Family | LCX (Low-Voltage CMOS) | LCX (Low-Voltage CMOS) | Same logic family ensures compatible input thresholds, output drive, and 5 V tolerant inputs. |
| Number of Channels | 8 | 8 | Both provide eight buffered channels, matching bus width requirements. |
| Output Drive Current | ±24 mA | ±24 mA | Identical drive strength ensures comparable fan-out and signal integrity performance. |
| 5 V Tolerant Inputs | Yes | Yes | Allows safe interfacing with 5 V logic without additional level shifting. |
| Package | TSSOP-20 | TSSOP-20 | Same package footprint, but pin functions differ due to the direction control pin, so PCB layout must account for the different pinout. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Identical temperature range supports use in industrial and commercial environments. |
| Propagation Delay (tPD) | ~6.5 ns (typical at 3.3 V) | ~6.5 ns (typical at 3.3 V) | Similar propagation delay ensures comparable timing performance in high-speed designs. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74LCX244MTC | 74LCX245TTR |
|---|---|---|
| Supplier | - | STMicroelectronics |
| Series | 74LCX | 74LCX |
| Part Status | Active | Obsolete |
| Logic Type | Buffer, Non-Inverting | Transceiver, Non-Inverting |
| Number of Elements | 2 | 1 |
| Number of Bits per Element | 4 | 8 |
| 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) | -55°C ~ 125°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 74LCX245TTR?
The 74LCX244MTC is an octal buffer/line driver with non-inverting 3-state outputs, organized as two 4-bit sections with separate output-enable pins. The 74LCX245TTR is an octal bus transceiver with non-inverting 3-state outputs, designed for bidirectional asynchronous communication between two data buses, with direction control and output-enable pins.
Are the 74LCX244MTC and 74LCX245TTR pin-to-pin compatible?
No. The 74LCX244MTC uses a 20-pin TSSOP package with two output-enable pins (1OE and 2OE) and no direction pin. The 74LCX245TTR uses a 20-pin TSSOP package with one direction pin (DIR) and one output-enable pin (OE). The pin functions differ, so they are not direct drop-in replacements.
Can the 74LCX244MTC be used as a bidirectional transceiver like the 74LCX245TTR?
No. The 74LCX244MTC is a unidirectional octal buffer/line driver. It cannot perform bidirectional data transfer because it lacks a direction control pin. The 74LCX245TTR is specifically designed for bidirectional bus communication.
What are the operating voltage and logic level specifications for both devices?
Both the 74LCX244MTC and 74LCX245TTR operate from a 2.0 V to 3.6 V VCC supply. They are 3.3 V logic devices with 5 V tolerant inputs and outputs, allowing interfacing with 5 V logic systems. These parameters are consistent across the LCX family from manufacturers such as ON Semiconductor (now onsemi) and NXP.
What are the package and mounting types for the 74LCX244MTC and 74LCX245TTR?
The 74LCX244MTC is supplied in a 20-pin TSSOP (Thin Shrink Small Outline Package) with a 4.4 mm body width, surface-mount. The 74LCX245TTR is also supplied in a 20-pin TSSOP with a 4.4 mm body width, surface-mount. Both use the same package footprint but have different pin functions.
What are the typical propagation delay and output drive characteristics of these devices?
Both devices typically have a propagation delay (tPD) of approximately 5.5 ns at 3.3 V VCC and 25°C. They provide ±24 mA output drive at 3.0 V VCC, making them suitable for bus driving and interfacing applications. These values are specified in manufacturer datasheets from onsemi and NXP.
Which device should be used for unidirectional signal buffering in a 3.3 V system?
The 74LCX244MTC is the appropriate choice for unidirectional signal buffering. It provides two independent 4-bit buffer sections with separate output-enable controls, allowing flexible control of signal flow in one direction only.
Which device should be used for bidirectional bus interfacing between two 3.3 V buses?
The 74LCX245TTR is the appropriate choice for bidirectional bus interfacing. Its DIR pin selects the direction of data flow (A to B or B to A), and the OE pin enables or disables both ports, making it suitable for multiplexed or shared bus architectures.
Are the 74LCX244MTC and 74LCX245TTR interchangeable in existing designs?
No. Because the pin functions differ (two output-enable pins versus one direction pin and one output-enable pin), they are not interchangeable without redesigning the PCB and control logic. Always verify pinout, control signals, and timing against the specific manufacturer datasheet before substitution.