Part A
74HCT245D
Toshiba Semiconductor và lưu trữ
- Lifecycle
- Active
- Stock
- 6073 PCS
- Package
- SOIC-14
- Series
- Logic - Buffers, Drivers, Receivers, Transceivers
Replacement verdict
Not a drop-in replacement
The 74HCT245D and 74HCT04D,653 are not functionally interchangeable despite sharing the 74HCT logic family and SOIC package. The 74HCT245D is an octal bidirectional bus transceiver with 3-state outputs and direction control, while the 74HCT04D,653 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 without redesigning the surrounding circuit.
Different logic function
Different channel count
Different output type
Different pinout
Parts at a glance
Part B
74HCT04D,653
NXP bán dẫn
- Lifecycle
- Active
- Stock
- 9812 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 | 74HCT245D | 74HCT04D,653 | Why it matters |
|---|---|---|---|
| Logic Function | Octal bus transceiver with 3-state outputs | Hex inverter | Defines the core function; these devices are not functionally interchangeable as they perform entirely different logic operations. |
| Number of Channels | 8 | 6 | Channel count determines how many independent signal lines can be handled by the device. |
| Direction Control | Bidirectional (DIR pin selects A-to-B or B-to-A) | Unidirectional (input to output only) | Bidirectional capability allows bus arbitration and data flow control, which a fixed inverter cannot provide. |
| Output Type | 3-state (tri-state) outputs with OE control | Standard push-pull outputs | Tri-state outputs enable bus sharing by disconnecting the device from the bus, while push-pull outputs are always driving. |
| Output Enable / Control Pins | OE (output enable) and DIR (direction) pins | None (no enable or direction control) | Control pins allow system-level management of bus access and signal routing, which is absent in a simple inverter. |
| Supply Voltage Range (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, ensuring electrical compatibility in mixed designs. |
| 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 when interfacing with TTL logic. |
| Propagation Delay (tpd) | Typical 12 ns at 5 V | Typical 9 ns at 5 V | Propagation delay affects maximum operating speed and timing margins in synchronous systems. |
| Output Drive Current (IOH/IOL) | ±6 mA (standard HCT drive) | ±4 mA (standard HCT drive) | Drive current determines the ability to drive loads such as LEDs, other logic inputs, or transmission lines. |
| Package | SOIC-20 (D suffix) | SOIC-14 (D suffix) | Different pin counts and package sizes affect PCB layout, footprint, and mechanical compatibility. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HCT245D | 74HCT04D,653 |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | 74HCT | 74HCT |
| Part Status | Active | Active |
| Logic Type | Transceiver, Non-Inverting | Inverter |
| Number of Circuits | - | 6 |
| Number of Inputs | - | 1 |
| Voltage - Supply | 4.5V ~ 5.5V | 4.5V ~ 5.5V |
| Current - Quiescent (Max) | - | 2 µA |
| Current - Output High Low | 6mA, 6mA | 4mA, 4mA |
| Logic Level - Low | - | 0.8V |
| Logic Level - High | - | 2V |
| Max Propagation Delay @ V Max CL | - | 19ns @ 4.5V, 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 74HCT245D and the 74HCT04D,653?
The 74HCT245D is an octal bus transceiver with 3-state outputs, designed for bidirectional asynchronous communication between data buses. The 74HCT04D,653 is a hex inverter with six independent inverting buffers. They serve fundamentally different logic functions and are not interchangeable.
Are the 74HCT245D and 74HCT04D,653 pin-compatible?
No. The 74HCT245D is typically supplied in a 20-pin SOIC package, while the 74HCT04D,653 is supplied in a 14-pin SOIC package. They have different pin counts, pin assignments, and PCB land patterns, so they cannot be used as drop-in replacements for each other.
Do both devices operate from the same supply voltage range?
Yes. Both the 74HCT245D and the 74HCT04D,653 are HCT-family logic devices specified for a nominal 5 V supply, with a recommended operating supply voltage range of 4.5 V to 5.5 V. This makes them compatible with TTL-level input thresholds in 5 V systems.
What is the difference in output drive capability between the two devices?
Both devices are specified with standard HCT-family output drive, typically ±4 mA at 5 V. The 74HCT245D provides this drive on eight 3-state outputs, while the 74HCT04D,653 provides it on six inverting outputs. The per-output drive specification is comparable, but the channel count and output type differ.
Can the 74HCT245D be used to replace the 74HCT04D,653 in an existing design?
No. The 74HCT245D is a bidirectional transceiver with direction control and output enable inputs, whereas the 74HCT04D,653 is a fixed-function hex inverter. The logic function, pinout, and package differ, so a direct replacement is not possible without redesigning the circuit.
What are the typical propagation delays for these devices?
For the 74HCT245D, typical propagation delay from A to B or B to A is approximately 12 ns at 5 V. For the 74HCT04D,653, typical propagation delay from input to output is approximately 11 ns at 5 V. Exact values depend on load conditions and are specified in the respective manufacturer datasheets.
Do both devices feature 3-state outputs?
No. The 74HCT245D has 3-state outputs controlled by an output enable (OE) pin, allowing the outputs to be placed in a high-impedance state. The 74HCT04D,653 has standard push-pull outputs without a 3-state capability.
Are the 74HCT245D and 74HCT04D,653 available in the same package types?
No. The 74HCT245D is commonly available in a 20-pin SOIC package. The 74HCT04D,653 is commonly available in a 14-pin SOIC package. Package type and pin count differ, which affects PCB layout and assembly.