Part A
74HCT04D
Toshiba Semiconductor and Storage
- Lifecycle
- Active
- Stock
- 4496 PCS
- Package
- SOIC-16
- Series
- Lógica - Gates e Inverters
Replacement verdict
Not a drop-in replacement
The 74HCT245D and 74HCT04D are not functionally interchangeable despite sharing the same 74HCT logic family and SOIC-14 package. The 74HCT245D is an octal bidirectional bus transceiver with three-state outputs and direction control, while the 74HCT04D is a hex inverting gate with unbuffered single-ended outputs. Their logic functions, channel counts, pinouts, and output drive characteristics differ fundamentally, so substituting one for the other is not feasible in any existing design.
Different logic function
Different channel count
Different pinout
Different output type
Parts at a glance
Part B
74HCT245D
Toshiba Semiconductor and Storage
- Lifecycle
- Active
- Stock
- 6073 PCS
- Package
- SOIC-14
- Series
- Lógica - Buffers, Drivers, Receivers, Transceivers
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HCT245D | 74HCT04D | Why it matters |
|---|---|---|---|
| Logic Function | Octal bus transceiver with 3-state outputs | Hex inverter | The core function determines whether the device can be substituted at all; a transceiver and an inverter perform fundamentally different logic operations. |
| Number of Channels | 8 | 6 | Channel count affects how many signal lines can be handled, impacting circuit design and board layout. |
| Direction Control | Bidirectional (DIR pin selects A-to-B or B-to-A) | Unidirectional (fixed inversion) | Bidirectional capability allows data flow in both directions, while a fixed inverter only processes signals one way. |
| Output Type | 3-state (tri-state) outputs with OE control | Standard push-pull outputs | Tri-state outputs enable bus sharing and high-impedance isolation, which standard push-pull outputs cannot provide. |
| Output Enable / Control Pins | OE (active low) and DIR | None | Control pins determine how the device is enabled or configured in a system; their absence or presence changes the interface requirements. |
| Supply Voltage (VCC) | 4.5 V to 5.5 V | 4.5 V to 5.5 V | Both devices operate from the same standard 5 V TTL-compatible supply range, so power rails are compatible. |
| Logic Family | HCT (High-speed CMOS, TTL-compatible) | HCT (High-speed CMOS, TTL-compatible) | Same logic family ensures compatible input thresholds and output drive characteristics with TTL logic levels. |
| Propagation Delay (tpd) | Typical 12 ns at 5 V | Typical 9 ns at 5 V | Propagation delay affects timing margins in synchronous and high-speed digital circuits. |
| Package | SOIC-20 (D suffix) | SOIC-14 (D suffix) | Different pin counts and package sizes mean the two parts are not footprint-compatible on a PCB. |
| Pin Count | 20 | 14 | Pin count directly affects PCB layout, routing, and whether a direct drop-in replacement is possible. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HCT04D | 74HCT245D |
|---|---|---|
| Series | 74HCT | 74HCT |
| Part Status | Active | Active |
| Logic Type | Inverter | Transceiver, Non-Inverting |
| Number of Circuits | 6 | - |
| Number of Inputs | 1 | - |
| Voltage - Supply | 4.5V ~ 5.5V | 4.5V ~ 5.5V |
| Current - Quiescent (Max) | 1 µA | - |
| Current - Output High Low | 4mA, 4mA | 6mA, 6mA |
| Logic Level - Low | 0.8V | - |
| Logic Level - High | 2V | - |
| Max Propagation Delay @ V Max CL | 16ns @ 5.5V, 50pF | - |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 125°C (TA) |
| 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 74HCT245D and 74HCT04D?
The 74HCT245D is an octal bus transceiver with 3-state outputs, designed for bidirectional asynchronous communication between data buses. The 74HCT04D is a hex inverter, providing six independent logic inversion gates.
Can the 74HCT245D and 74HCT04D be used interchangeably in a circuit design?
No, they are not interchangeable. The 74HCT245D is an 8-bit bidirectional transceiver with direction and output-enable control, while the 74HCT04D is a hex inverter with fixed unidirectional logic inversion. Their pinouts, functions, and control logic differ fundamentally.
What are the key electrical differences between the 74HCT245D and 74HCT04D?
Both devices operate with a 4.5 V to 5.5 V supply and are HCT-type, offering TTL-compatible inputs. The 74HCT245D provides 3-state outputs with ±6 mA output drive (at 4.5 V), while the 74HCT04D provides standard push-pull outputs with ±4 mA output drive (at 4.5 V). Propagation delays and input capacitance also differ per the respective datasheets.
Do the 74HCT245D and 74HCT04D have the same package and pin configuration?
No. The 74HCT245D is typically supplied in a 20-pin SOIC package (D suffix), while the 74HCT04D is typically supplied in a 14-pin SOIC package. Pin counts, pin assignments, and PCB land patterns are different.
Which device is suitable for bus-oriented data transmission?
The 74HCT245D is specifically designed for bus-oriented systems, featuring non-inverting 3-state outputs and direction control (DIR) and output enable (OE) pins for bidirectional data flow. The 74HCT04D is not intended for bus transceiver applications.
Are both the 74HCT245D and 74HCT04D compatible with 5 V TTL logic levels?
Yes. Both are HCT-family devices, meaning they have TTL-compatible input thresholds when operated at a 5 V supply, allowing direct interface with TTL logic while maintaining CMOS output characteristics.
What is the difference in output drive capability between the 74HCT245D and 74HCT04D?
At a 4.5 V supply, the 74HCT245D specifies ±6 mA output current, whereas the 74HCT04D specifies ±4 mA output current. This difference affects fan-out and trace driving capability in a given design.
Can the 74HCT04D be used to buffer or drive a bus that requires bidirectional communication?
No. The 74HCT04D is a unidirectional hex inverter with push-pull outputs and no 3-state or direction control. Bidirectional bus applications require a transceiver such as the 74HCT245D.