Part A
74HC245D,653
NXP USA Inc.
- Lifecycle
- Active
- Stock
- 8186 PCS
- Series
- Lógica - Buffers, Drivers, Receivers, Transceivers
Replacement verdict
Not a drop-in replacement
The 74HC259D and 74HC245D,653 are functionally unrelated logic ICs and cannot serve as substitutes for one another. The 74HC259D is an 8-bit addressable latch with decoder and storage registers, while the 74HC245D,653 is an octal bidirectional bus transceiver with 3-state outputs. Their internal architectures, pin functions, and intended applications differ fundamentally, making direct replacement impossible without complete circuit redesign.
Different logic function
Different output type
Different pin function
Different application role
Parts at a glance
Part B
74HC259D
Toshiba Semiconductor and Storage
- Lifecycle
- Active
- Stock
- 7207 PCS
- Package
- SOIC-20
- Series
- Lógica - Latches
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC259D | 74HC245D,653 | Why it matters |
|---|---|---|---|
| Logic Function | 8-bit addressable latch | Octal bus transceiver, 3-state | Defines the core function; these devices are not functionally interchangeable as they perform entirely different logic operations. |
| Number of Outputs | 8 (latched, non-inverting) | 8 (3-state, bidirectional) | Output count and type affect how the device can drive downstream loads and whether outputs can be shared on a bus. |
| Output Type | Standard push-pull (non-3-state) | 3-state (tri-state) | 3-state outputs allow bus sharing; the latch's push-pull outputs cannot be tied together on a shared bus. |
| Directionality | Unidirectional (input to latched output) | Bidirectional (A to B or B to A) | Bidirectional capability is essential for bus transceiver applications, which the latch cannot provide. |
| Latching / Storage | Yes, addressable latch with 8 storage elements | No storage; transparent buffer | Latches retain data, while transceivers only pass signals through; this fundamentally changes circuit behavior. |
| Control Inputs | Address inputs (A0-A2), Enable (E), Clear | Direction (DIR), Output Enable (OE) | Different control schemes mean the devices require different driving logic and cannot be swapped without redesign. |
| Supply Voltage Range | 2.0 V to 6.0 V | 2.0 V to 6.0 V | Both operate over the standard HC-family supply range, so voltage compatibility is not a differentiator. |
| Package | SO16 (SOIC-16) | SO20 (SOIC-20) | Different pin counts and package sizes affect PCB footprint and layout compatibility. |
| Logic Family | 74HC (High-speed CMOS) | 74HC (High-speed CMOS) | Same logic family ensures comparable input thresholds, noise margins, and drive characteristics. |
| Typical Propagation Delay | ~17 ns at 4.5 V | ~8 ns at 4.5 V | Speed differences can affect timing margins in high-frequency or timing-critical designs. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC245D,653 | 74HC259D |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Discontinued at DigiKey | Active |
| Base Product Number | 74HC245 | - |
| Logic Type | Transceiver, Non-Inverting | D-Type, Addressable |
| Number of Elements | 1 | - |
| Number of Bits per Element | 8 | - |
| Output Type | 3-State | Standard |
| Current - Output High, Low | 7.8mA, 7.8mA | - |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Packaging | Tape & Reel (TR) | - |
| Circuit | - | 1:8 |
| Independent Circuits | - | 1 |
| Delay Time - Propagation | - | 22ns |
| Current - Output High Low | - | 5.2mA, 5.2mA |
Frequently asked questions
What are the primary functional differences between the 74HC259D and the 74HC245D,653?
The 74HC259D is an 8-bit addressable latch that stores individual bits and provides both latching and demultiplexing functions. The 74HC245D,653 is an octal bus transceiver designed for bidirectional asynchronous communication between two data buses, featuring non-inverting three-state outputs.
Are the 74HC259D and 74HC245D,653 pin-to-pin compatible?
No. The 74HC259D is typically supplied in a 16-pin SOIC package, while the 74HC245D,653 is supplied in a 20-pin SOIC package. They have different pin counts and pin functions, so they are not drop-in replacements for each other.
Can the 74HC259D and 74HC245D,653 operate at the same supply voltage range?
Yes. Both devices are members of the 74HC logic family and operate over a standard supply voltage range of 2.0 V to 6.0 V, with typical operation at 5.0 V.
Does the 74HC245D,653 have three-state outputs like the 74HC259D?
The 74HC245D,653 features three-state outputs on both the A and B ports, controlled by the direction (DIR) and output enable (OE) pins. The 74HC259D has active-low latching outputs that are not three-state; its outputs are either high or low based on the latched data.
Which device is suitable for bidirectional data bus buffering?
The 74HC245D,653 is specifically designed for bidirectional data bus buffering and transmission. The 74HC259D is not intended for bus buffering; it is used for addressable latching and demultiplexing applications.
What are the typical propagation delay characteristics of these two devices?
At a 5 V supply, the 74HC259D typically exhibits a propagation delay from address or data inputs to outputs of approximately 20 ns to 30 ns. The 74HC245D,653 typically exhibits a propagation delay from A to B or B to A of approximately 10 ns to 15 ns. Exact values depend on load conditions and are specified in the respective manufacturer datasheets.
Can the 74HC259D and 74HC245D,653 be used together in the same system?
Yes. They serve different functions and can be used together. For example, the 74HC259D can latch control or address signals, while the 74HC245D,653 can buffer data between buses in the same digital system.