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 74VHCT374AMTC are not functionally interchangeable. The 74VHC244FT is a quad non-inverting buffer/line driver with 3-state outputs, while the 74VHCT374AMTC is an octal D-type flip-flop with 3-state outputs. They differ in logic function, channel count, package type, and input threshold technology, making direct substitution impossible without circuit redesign.
Different logic function
Different channel count
Different package type
Different input threshold technology
Parts at a glance
Part B
74VHCT374AMTC
onsemi
- Lifecycle
- Active
- Stock
- 6920 PCS
- Series
- Logic - Flip Flops
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 | 74VHCT374AMTC | Why it matters |
|---|---|---|---|
| Logic Function | Octal Buffer/Line Driver (3-state) | Octal D-Type Flip-Flop (3-state) | These are fundamentally different logic functions; a buffer passes signals combinationally while a flip-flop latches data on a clock edge, so they are not direct substitutes. |
| Logic Family | VHC (CMOS) | VHCT (CMOS, TTL-compatible inputs) | VHCT inputs are compatible with TTL voltage levels, while VHC inputs are CMOS-level; this affects interfacing with legacy TTL logic. |
| Number of Channels | 8 (two 4-bit groups) | 8 | Both handle 8 signals, but the buffer has two independent enable groups while the flip-flop shares a common clock and output enable. |
| Output Type | 3-state | 3-state | Both offer high-impedance outputs for bus sharing, but the control mechanism differs (enable vs. clock/OE). |
| Propagation Delay (typ) | ~3.5 ns at 5 V | ~5.4 ns at 5 V | Faster propagation delay in the buffer allows quicker signal throughput, which matters in timing-critical paths. |
| Supply Voltage Range | 2.0 V to 5.5 V | 4.5 V to 5.5 V | The wider operating range of the VHC device supports low-voltage systems, while the VHCT part is limited to 5 V operation. |
| Input Compatibility | CMOS | TTL | TTL-compatible inputs allow direct connection to older TTL logic without level shifting, which the VHC part may require. |
| Package | TSSOP-20 | TSSOP-20 | Same package footprint allows drop-in board placement, though pin functions differ between the two devices. |
| Clock Requirement | None (combinational) | Yes (edge-triggered) | The flip-flop requires a clock signal to capture data, whereas the buffer operates without any clock, affecting system timing design. |
| Output Drive Current | ±8 mA | ±8 mA | Identical drive strength means both can drive similar loads, but the functional difference still prevents direct substitution. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74VHC244FT | 74VHCT374AMTC |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC,onsemi |
| Series | 74VHC | 74VHCT |
| Part Status | Active | Obsolete |
| Function | - | Standard |
| Type | - | D-Type |
| Output Type | 3-State | Tri-State, Non-Inverted |
| Number of Elements | 2 | 1 |
| Number of Bits per Element | 4 | 8 |
| Clock Frequency | - | 130 MHz |
| Max Propagation Delay @ V Max CL | - | 10.4ns @ 5V, 50pF |
| Trigger Type | - | Positive Edge |
| Current - Output High Low | 8mA, 8mA | 8mA, 8mA |
| Voltage - Supply | 2V ~ 5.5V | 4.5V ~ 5.5V |
| Current - Quiescent (Iq) | - | 4 µA |
| Input Capacitance | - | 4 pF |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 85°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Logic Type | Buffer, Non-Inverting | - |
Frequently asked questions
What are the primary functional differences between the 74VHC244FT and the 74VHCT374AMTC?
The 74VHC244FT is an octal non-inverting buffer/line driver with 3-state outputs, while the 74VHCT374AMTC is an octal D-type flip-flop with 3-state outputs. The 74VHC244FT provides combinational buffering, whereas the 74VHCT374AMTC provides edge-triggered storage of data.
Are the 74VHC244FT and 74VHCT374AMTC pin-compatible?
No. The 74VHC244FT is typically supplied in a TSSOP-20 package, and the 74VHCT374AMTC is supplied in a TSSOP-20 package as well, but their pin functions differ. The 74VHC244FT has two active-low output enables (1OE, 2OE) and no clock pin, while the 74VHCT374AMTC has a clock input (CP) and an active-low output enable (OE). Therefore, they are not direct pin-to-pin replacements.
Can the 74VHC244FT and 74VHCT374AMTC operate at the same supply voltage?
Yes. Both devices are specified for a nominal supply voltage range of 2.0 V to 5.5 V, with the 74VHCT374AMTC also supporting 5 V tolerant inputs when operated at 5 V. However, the 74VHCT374AMTC is specifically designed for TTL-compatible input thresholds, while the 74VHC244FT uses CMOS input thresholds.
What is the difference in input threshold levels between the 74VHC244FT and the 74VHCT374AMTC?
The 74VHC244FT has CMOS input thresholds, typically 0.7 × VCC for a high input and 0.3 × VCC for a low input. The 74VHCT374AMTC has TTL-compatible input thresholds, typically 2.0 V for a high input and 0.8 V for a low input, making it suitable for interfacing with TTL logic levels.
Do both devices feature 3-state outputs?
Yes. Both the 74VHC244FT and the 74VHCT374AMTC provide 3-state outputs, allowing their outputs to be placed in a high-impedance state for bus-oriented applications. The 74VHC244FT controls the 3-state condition via two output enable pins, while the 74VHCT374AMTC controls it via a single output enable pin.
Which device is more suitable for capturing and storing data?
The 74VHCT374AMTC is more suitable for capturing and storing data because it contains octal D-type flip-flops that latch data on the rising edge of the clock signal. The 74VHC244FT does not have storage elements and only buffers the input signals to the outputs.
Are the 74VHC244FT and 74VHCT374AMTC available in the same package type?
Both devices are commonly available in TSSOP-20 packages, but the 74VHC244FT may also be offered in other package options depending on the manufacturer. The 74VHCT374AMTC is typically provided in a TSSOP-20 package. Package compatibility must be verified against the specific manufacturer datasheet.
Can the 74VHC244FT be used as a direct substitute for the 74VHCT374AMTC in a design?
No. The 74VHC244FT is a combinational buffer without clocked storage, while the 74VHCT374AMTC is a clocked D-type flip-flop. Substituting one for the other would change the logic function and timing behavior of the circuit, so they are not functionally interchangeable.