Part A
74VHC244FT
東芝セミコンダクター・アンド・ストレージ
- Lifecycle
- Active
- Stock
- 2156 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
Replacement verdict
Compatible functional replacement candidate
The 74VHC244FT and 74VHC126TTR are both quad buffer/line driver devices from the VHC family, but they are not pin-to-pin equivalent due to differing output enable logic and package options. The 74VHC244FT offers dual active-low output enables with a wider package selection, while the 74VHC126TTR provides individual active-high enables per channel. Designers must verify enable polarity, board footprint, and thermal requirements before substituting one for the other in existing designs.
Output Enable Logic
Validation required
Channel Count
High match
Package Type
Validation required
Logic Family
High match
Parts at a glance
Part B
74VHC126TTR
RFE/フューゼテック
- Lifecycle
- Active
- Stock
- 4191 個数
- Package
- TSSOP-14
- 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 | 74VHC244FT | 74VHC126TTR | 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 the basic signal-routing function; a direct substitution requires matching channel count and function. |
| Number of Channels | 8 | 4 | Channel count must match the application's signal count; fewer channels may require additional components. |
| Control Input Type | Common dual enable (active-low OE) | Independent per-channel enable (active-high OE) | Enable polarity and independence affect how outputs are gated and whether channels can be controlled separately. |
| Output Type | 3-state, non-inverting | 3-state, non-inverting | Both are non-inverting 3-state, but the enable architecture differs, affecting bus-sharing behavior. |
| Supply Voltage Range | 2.0 V to 5.5 V | 2.0 V to 5.5 V | Operating voltage range must be compatible with the system supply for reliable logic levels. |
| Propagation Delay (tpd) | ~5.5 ns at 5 V | ~5.5 ns at 5 V | Timing must be compatible with the system clock and signal path requirements. |
| Output Drive Current | ±8 mA | ±8 mA | Drive strength determines fan-out and ability to drive capacitive or low-impedance loads. |
| Package | TSSOP-20 | TSSOP-14 | Package footprint and pin count must match the PCB layout for physical compatibility. |
| Pin Count | 20 | 14 | Pin count affects board layout and cannot be substituted without redesign. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range must cover the application environment for reliable operation. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74VHC244FT | 74VHC126TTR |
|---|---|---|
| Supplier | - | STMicroelectronics |
| Series | 74VHC | 74VHC |
| 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 | 8mA, 8mA | 8mA, 8mA |
| Voltage - Supply | 2V ~ 5.5V | 2V ~ 5.5V |
| Operating Temperature | -40°C ~ 125°C (TA) | -55°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the main functional differences between the 74VHC244FT and the 74VHC126TTR?
The 74VHC244FT is an octal non-inverting buffer/line driver with 3-state outputs, featuring two active-low output enable pins that control four outputs each. The 74VHC126TTR is a quad non-inverting buffer/line driver with 3-state outputs, where each of the four buffers has its own independent active-high output enable pin. The 74VHC244FT provides eight buffers in a 20-pin package, while the 74VHC126TTR provides four buffers in a 14-pin package.
Are the 74VHC244FT and 74VHC126TTR pin-to-pin compatible?
No. The 74VHC244FT is typically supplied in a 20-pin TSSOP (FT suffix) package, while the 74VHC126TTR is supplied in a 14-pin TSSOP package. They have different pin counts, different pinouts, and different package footprints, so they are not drop-in replacements for each other.
What is the difference in output enable logic between these two devices?
The 74VHC244FT uses two active-low output enable pins (1OE and 2OE), each controlling a group of four outputs. The 74VHC126TTR uses four independent active-high output enable pins (1OE through 4OE), one per buffer. This means the 74VHC126TTR allows individual channel control, while the 74VHC244FT controls outputs in two groups of four.
Do both devices operate at the same supply voltage range and logic family?
Yes. Both are members of the 74VHC (Very High Speed CMOS) logic family and operate over a recommended supply voltage range of 2.0 V to 5.5 V. They are both designed for 5 V tolerant inputs when used at lower supply voltages, consistent with the VHC family specifications.
Can the 74VHC126TTR be used to replace the 74VHC244FT in an existing design?
Not directly. Although both are non-inverting 3-state buffers in the VHC family, the 74VHC126TTR has only four buffers versus eight on the 74VHC244FT, uses active-high enables instead of active-low enables, and has a different pin count and pinout. Any substitution would require a complete review of channel count, enable polarity, pin mapping, and PCB layout.
What are the typical propagation delay and drive characteristics of these devices?
Both devices are VHC-family CMOS buffers with typical propagation delays in the range of approximately 3.5 ns to 5.5 ns at 5 V supply, depending on load conditions, and both provide symmetric output drive of approximately ±8 mA at 5 V. For exact guaranteed limits, refer to the respective manufacturer datasheets, as values vary by test conditions and temperature.
Which device is better suited for bus driving versus individual signal buffering?
The 74VHC244FT, with eight buffers and grouped enable control, is typically used for bus driving and multi-bit signal buffering where outputs are enabled in groups. The 74VHC126TTR, with four independently enabled buffers, is better suited for applications requiring individual channel control, such as mixed signal gating or selective buffering of separate lines.
Are both devices available in TSSOP packages?
Yes. The 74VHC244FT is commonly offered in a 20-pin TSSOP package (the "FT" suffix typically denotes TSSOP for Toshiba VHC devices). The 74VHC126TTR is commonly offered in a 14-pin TSSOP package (the "TTR" suffix typically denotes TSSOP tape and reel). Package dimensions and pin counts differ, so PCB footprints are not interchangeable.