Part A
74VHC245FT
東芝電晶體與存儲
- Lifecycle
- Active
- Stock
- 4188 件
- Package
- TSSOP-20
- Series
- 邏輯-緩衝器、驅動器、接收器、收發器
Replacement verdict
Not a drop-in replacement
The 74VHC245FT and 74VHC04FT are not functionally interchangeable. The 74VHC245FT is an octal bidirectional transceiver with 3-state outputs, while the 74VHC04FT is a hex inverter with unbuffered outputs. They differ in logic function, channel count, output type, and pin configuration, making direct substitution impossible without circuit redesign.
Different logic function
Different channel count
Different output type
Different pin configuration
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 | 74VHC04FT | Why it matters |
|---|---|---|---|
| Logic Function | Octal Bus Transceiver, 3-state | Hex Inverter | Defines the core function; a transceiver provides bidirectional bus interfacing while an inverter provides signal inversion, so they are not functionally interchangeable. |
| Number of Channels | 8 | 6 | Channel count determines how many independent signal lines can be handled per package. |
| Direction Control | Direction pin (A-to-B or B-to-A) with output enable | Unidirectional (fixed input-to-output) | Bidirectional control allows bus multiplexing and isolation, which a fixed-direction inverter cannot provide. |
| Output Type | 3-state | Push-pull | 3-state outputs permit high-impedance bus sharing, while push-pull outputs always drive the line. |
| Supply Voltage Range | 2.0 V to 5.5 V | 2.0 V to 5.5 V | Both support the same VHC operating range, allowing use in 2.5 V, 3.3 V, and 5 V systems. |
| Logic Family | VHC (Very High Speed CMOS) | VHC (Very High Speed CMOS) | Same family implies compatible input thresholds, noise margins, and drive characteristics. |
| Package | TSSOP-20 (FT suffix) | TSSOP-14 (FT suffix) | Package footprint and pin count affect PCB layout and cannot be swapped without redesign. |
| Propagation Delay (typical) | ~4.5 ns at 5 V | ~5.5 ns at 5 V | Timing differences affect signal integrity and maximum operating frequency in synchronous designs. |
| Pin Count | 20 | 14 | Different pin counts mean incompatible footprints and pinouts, preventing direct drop-in substitution. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74VHC245FT | 74VHC04FT |
|---|---|---|
| Supplier | - | Toshiba Semiconductor and Storage |
| Series | 74VHC | 74VHC |
| Part Status | Active | Active |
| Logic Type | Transceiver, Non-Inverting | Inverter |
| Number of Circuits | - | 6 |
| Number of Inputs | - | 1 |
| Voltage - Supply | 2V ~ 5.5V | 2V ~ 5.5V |
| Current - Quiescent (Max) | - | 2 µA |
| Current - Output High Low | 8mA, 8mA | 8mA, 8mA |
| Max Propagation Delay @ V Max CL | - | 7.5ns @ 5V, 50pF |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°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
What are the primary functions of the 74VHC245FT and 74VHC04FT?
The 74VHC245FT is an octal bidirectional transceiver with 3-state outputs, designed for asynchronous two-way data transmission between buses. The 74VHC04FT is a hex inverter, providing six independent logic inversion gates. They serve fundamentally different logic functions and are not interchangeable.
Do the 74VHC245FT and 74VHC04FT share the same package and pinout?
Both devices are offered in the TSSOP-20 package (suffix FT) by Toshiba, but their pinouts differ. The 74VHC245FT uses all 20 pins for octal transceiver functions including direction and output enable controls, while the 74VHC04FT uses only 14 pins for six inverters in a 20-pin package with additional pins unconnected or internally not used. They are not pin-to-pin compatible.
Can the 74VHC245FT be used to replace the 74VHC04FT in an existing design?
No. The 74VHC245FT is a bidirectional transceiver with 3-state outputs and direction control, while the 74VHC04FT is a fixed-function hex inverter. Their logic functions, pinouts, and control interfaces are different, so a direct replacement is not possible without redesigning the circuit.
What are the key electrical characteristics of the 74VHC245FT?
The 74VHC245FT operates from a 2.0 V to 5.5 V supply, features 3-state outputs for bus isolation, and provides bidirectional data flow with direction and output enable controls. It is specified for balanced drive capability and is suitable for bus-oriented applications in 5 V and 3.3 V systems.
What are the key electrical characteristics of the 74VHC04FT?
The 74VHC04FT operates from a 2.0 V to 5.5 V supply and contains six independent inverters. It provides standard VHC-family switching characteristics, including low propagation delay and balanced output drive, and is commonly used for signal inversion, clock generation, and logic level conversion.
Are both devices compatible with 5 V and 3.3 V logic systems?
Yes. Both the 74VHC245FT and 74VHC04FT are part of the VHC family and support a supply voltage range of 2.0 V to 5.5 V, making them compatible with mixed 5 V and 3.3 V logic environments when used within specified operating conditions.
Which device is better for bus isolation and data direction control?
The 74VHC245FT is specifically designed for bus isolation and bidirectional data flow with 3-state outputs and direction control. The 74VHC04FT does not provide bus isolation or direction control, so the 74VHC245FT is the appropriate choice for those functions.
Do both devices have the same operating temperature range?
Both the 74VHC245FT and 74VHC04FT are specified for the industrial temperature range of -40 °C to +85 °C, as documented in Toshiba's VHC series datasheets. This makes them suitable for industrial and commercial applications within that range.