Part A
74VHC245FT
Toshiba Semiconductor và lưu trữ
- Lifecycle
- Active
- Stock
- 4188 PCS
- Package
- TSSOP-20
- Series
- Logic - Buffers, Drivers, Receivers, Transceivers
Replacement verdict
Not a drop-in replacement
The 74VHC245FT and 74VHCT04ATTR are functionally incompatible devices and cannot serve as substitutes for one another. The 74VHC245FT is an octal bidirectional bus transceiver with three-state outputs, while the 74VHCT04ATTR is a hex inverting gate with TTL-compatible inputs. They differ in logic function, channel count, output configuration, and package type, making direct replacement impossible without circuit redesign.
Different logic function
Different channel count
Different output type
Different package type
Parts at a glance
Part B
74VHCT04ATTR
STMicroelectronics
- Lifecycle
- Active
- Stock
- 6592 PCS
- Series
- Logic - Gates and Inverters
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74VHC245FT | 74VHCT04ATTR | Why it matters |
|---|---|---|---|
| Logic Function | Octal Bus Transceiver, 3-State | Hex Inverter | The two devices perform fundamentally different logic functions, so they are not direct functional substitutes in a circuit. |
| Number of Channels | 8 | 6 | Channel count determines how many independent signal lines the device can handle. |
| Logic Family | VHC (Very High Speed CMOS) | VHCT (Very High Speed CMOS with TTL-compatible inputs) | VHCT inputs are TTL-voltage compatible, while VHC inputs are CMOS-level, affecting interoperability with other logic families. |
| Output Type | 3-State | Totem-Pole | 3-state outputs allow bus sharing and high-impedance disconnection, whereas totem-pole outputs cannot be tied together. |
| Direction Control | Bidirectional (DIR pin) | Unidirectional | Bidirectional capability enables data flow in both directions, which a fixed inverter cannot provide. |
| Propagation Delay (typ) | ~3.5 ns at 5 V | ~5.5 ns at 5 V | Propagation delay affects maximum operating frequency and timing margins in synchronous designs. |
| Supply Voltage Range | 2.0 V to 5.5 V | 4.5 V to 5.5 V | A wider supply range offers more flexibility in low-voltage and mixed-voltage systems. |
| Input Voltage Compatibility | CMOS-level | TTL-level | TTL-compatible inputs allow direct interfacing with TTL logic without additional level shifting. |
| Package | TSSOP-20 | TSSOP-14 | Different pin counts and package sizes affect PCB layout, footprint, and board space requirements. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Both devices support industrial temperature ranges, making them suitable for similar environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74VHC245FT | 74VHCT04ATTR |
|---|---|---|
| Supplier | - | STMicroelectronics |
| Series | 74VHC | 74VHCT |
| Part Status | Active | Obsolete |
| Logic Type | Transceiver, Non-Inverting | Inverter |
| Number of Circuits | - | 6 |
| Number of Inputs | - | 1 |
| Voltage - Supply | 2V ~ 5.5V | 4.5V ~ 5.5V |
| Current - Quiescent (Max) | - | 2 µA |
| Current - Output High Low | 8mA, 8mA | 8mA, 8mA |
| Logic Level - Low | - | 0.8V |
| Logic Level - High | - | 2V |
| Max Propagation Delay @ V Max CL | - | 7.7ns @ 5V, 50pF |
| Operating Temperature | -40°C ~ 125°C (TA) | -55°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Number of Elements | 1 | - |
| Number of Bits per Element | 8 | - |
| Output Type | 3-State | - |
Frequently asked questions
Are the 74VHC245FT and 74VHCT04ATTR functionally interchangeable?
No. The 74VHC245FT is an octal bus transceiver with 3-state outputs, while the 74VHCT04ATTR is a hex inverter. They perform different logic functions and cannot be used as direct substitutes for one another.
What are the primary differences between the 74VHC245FT and 74VHCT04ATTR?
The 74VHC245FT is an octal bidirectional bus transceiver with non-inverting 3-state outputs, designed for bus-oriented data transmission. The 74VHCT04ATTR is a hex inverting buffer with TTL-compatible inputs. They differ in logic function, channel count, output type, and input threshold characteristics.
Do the 74VHC245FT and 74VHCT04ATTR use the same package type?
No. The 74VHC245FT is supplied in a TSSOP-20 package, while the 74VHCT04ATTR is supplied in a TSSOP-14 package. The different pin counts and package sizes prevent direct PCB footprint compatibility.
What is the difference between the VHC and VHCT logic families used in these parts?
VHC (Very High-speed CMOS) devices have CMOS-compatible input thresholds and are optimized for balanced noise immunity and speed. VHCT (Very High-speed CMOS with TTL-compatible inputs) devices feature TTL-compatible input thresholds, allowing direct interfacing with TTL logic levels while maintaining CMOS output drive characteristics.
Can the 74VHC245FT and 74VHCT04ATTR operate from the same supply voltage?
Yes. Both devices are specified for operation over a supply voltage range of 2.0 V to 5.5 V, making them compatible with common 3.3 V and 5 V logic systems.
What is the function of the direction control pin on the 74VHC245FT?
The 74VHC245FT includes a direction control (DIR) pin that determines whether data flows from the A bus to the B bus or from the B bus to the A bus. An output enable (OE) pin is also provided to place the outputs in a high-impedance state.
Does the 74VHCT04ATTR have 3-state outputs?
No. The 74VHCT04ATTR is a hex inverter with standard push-pull outputs. It does not provide a high-impedance output state.
Are the 74VHC245FT and 74VHCT04ATTR available in automotive-qualified versions?
Automotive qualification depends on the specific ordering part number and manufacturer. Designers should verify AEC-Q100 qualification status directly from the manufacturer datasheet or an authorized distributor before selecting either device for automotive applications.