Part A
74VHC244FT
Toshiba Semiconductor và lưu trữ
- Lifecycle
- Active
- Stock
- 2156 PCS
- Package
- TSSOP-20
- Series
- Logic - Buffers, Drivers, Receivers, Transceivers
Replacement verdict
Not a drop-in replacement
The 74VHC244FT and 74VHC08FT are not functionally interchangeable. The 74VHC244FT is an octal non-inverting buffer/line driver with 3-state outputs, while the 74VHC08FT is a quad 2-input AND gate. Their logic functions, channel counts, output configurations, and pin assignments differ fundamentally, making direct substitution impossible without circuit redesign.
Different logic function
Different channel count
Different output type
Different pin assignment
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 | 74VHC08FT | Why it matters |
|---|---|---|---|
| Logic Function | Octal Buffer/Line Driver (3-state) | Quad 2-Input AND Gate | Defines the fundamental logic operation; these devices are not functionally interchangeable. |
| Number of Channels | 8 | 4 | Determines how many independent signal paths can be handled by the device. |
| Output Type | 3-State | Push-Pull | 3-state outputs allow bus sharing; push-pull outputs cannot be tied together directly. |
| Input Type | Single-ended (with dual enable) | Single-ended (2 inputs per gate) | Affects how signals are applied and combined within the logic device. |
| Propagation Delay (typ) | 3.8 ns at 5 V | 4.3 ns at 5 V | Influences maximum operating frequency and timing margins in a system. |
| Supply Voltage Range | 2.0 V to 5.5 V | 2.0 V to 5.5 V | Both support similar low-voltage logic levels, but the range must match the system supply. |
| Output Drive Current | ±8 mA at 5 V | ±8 mA at 5 V | Determines the ability to drive loads such as LEDs or transmission lines. |
| Package | TSSOP-20 | TSSOP-14 | Physical footprint and pin count affect PCB layout and assembly compatibility. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Ensures reliable operation across the intended environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74VHC244FT | 74VHC08FT |
|---|---|---|
| Series | 74VHC | TC74VHC |
| Part Status | Active | Active |
| Logic Type | Buffer, Non-Inverting | AND Gate |
| Number of Circuits | - | 4 |
| Number of Inputs | - | 2 |
| Voltage - Supply | 2V ~ 5.5V | 2V ~ 5.5V |
| Current - Quiescent (Max) | - | 2 µA |
| Current - Output High, Low | - | 8mA, 8mA |
| Input Logic Level - Low | - | 0.5V |
| Input Logic Level - High | - | 1.5V |
| Max Propagation Delay @ V, Max CL | - | 7.9ns @ 5V, 50pF |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
| Base Product Number | - | 74VHC08 |
| Number of Elements | 2 | - |
| Number of Bits per Element | 4 | - |
| Output Type | 3-State | - |
| Current - Output High Low | 8mA, 8mA | - |
Frequently asked questions
What are the primary functions of the 74VHC244FT and 74VHC08FT?
The 74VHC244FT is an octal non-inverting buffer/line driver with 3-state outputs, while the 74VHC08FT is a quad 2-input AND gate. They perform fundamentally different logic functions and are not interchangeable.
Do the 74VHC244FT and 74VHC08FT share the same package and pinout?
Both devices are offered in the TSSOP-14 package (suffix FT), but their pinouts differ. The 74VHC244FT uses the 14-pin TSSOP with two active-low output enable pins, whereas the 74VHC08FT uses the same 14-pin TSSOP with four independent 2-input AND gates. Pin functions are not compatible.
Can the 74VHC244FT and 74VHC08FT operate from the same supply voltage range?
Yes. Both are 74VHC-series CMOS devices specified for a supply voltage range of 2.0 V to 5.5 V, with typical operation at 3.3 V or 5 V.
What are the output drive characteristics of the 74VHC244FT compared to the 74VHC08FT?
The 74VHC244FT provides 3-state outputs with ±8 mA output drive at 5 V (typical VHC specification). The 74VHC08FT provides standard CMOS push-pull outputs with ±8 mA output drive at 5 V. The 74VHC244FT adds high-impedance output capability via enable pins, which the 74VHC08FT does not have.
Are the 74VHC244FT and 74VHC08FT pin-to-pin compatible with any legacy logic families?
Both devices are functionally compatible with equivalent functions in the 74HC, 74HCT, and 74AHC families when used within the same supply voltage and logic-level constraints. However, direct substitution requires verification of input threshold, drive current, and propagation delay against the target design.
What are the typical propagation delays for the 74VHC244FT and 74VHC08FT?
At 5 V supply, the 74VHC244FT has a typical propagation delay of approximately 3.8 ns (tPLH/tPHL). The 74VHC08FT has a typical propagation delay of approximately 4.3 ns at 5 V. Actual values depend on load capacitance and operating conditions as specified in the manufacturer datasheets.
Can the 74VHC244FT be used to drive the inputs of the 74VHC08FT?
Yes, provided both devices operate from the same supply voltage and the 74VHC244FT output current and voltage levels meet the 74VHC08FT input requirements. The 74VHC244FT 3-state outputs must be enabled and not in high-impedance state during operation.
What are the operating temperature ranges for the 74VHC244FT and 74VHC08FT?
Both devices are specified for an operating ambient temperature range of -40 °C to +85 °C (industrial grade) or -40 °C to +125 °C depending on the specific manufacturer variant. Designers must confirm the exact temperature grade from the ordered part number and datasheet.