Part A
74HC259D
Toshiba Semiconductor and Storage
- Lifecycle
- Active
- Stock
- 7207 PCS
- Package
- SOIC-20
- Series
- Lógica - Latches
Replacement verdict
Not a drop-in replacement
The 74HC259D and 74HC244D,653 are functionally unrelated ICs: the 74HC259D is an 8-bit addressable latch with 3-to-8 decoding, while the 74HC244D,653 is an octal non-inverting 3-state buffer/line driver. They differ in logic function, output behavior, channel count, and pinout, so neither device can directly substitute for the other in an existing design.
Different logic function
Different output type
Different channel count
Different pinout
Parts at a glance
Part B
74HC244D,653
NXP USA Inc.
- Lifecycle
- Active
- Stock
- 6812 PCS
- Package
- SOIC-20
- 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 | 74HC259D | 74HC244D,653 | Why it matters |
|---|---|---|---|
| Logic Function | 8-bit addressable latch | Octal buffer/line driver (3-state) | The core function determines whether the device can store/select bits or only buffer/drive signals, making them non-interchangeable in most designs. |
| Output Type | Latched, non-inverting (parallel latched outputs) | 3-state, non-inverting | 3-state outputs allow bus sharing, while latched outputs retain data; this affects bus architecture and signal control. |
| Number of Outputs | 8 latched outputs | 8 buffered outputs | Both have 8 channels, but the nature of the outputs differs, influencing how many independent signals can be driven or stored. |
| Control Inputs | Address inputs (A0-A2), Enable (E), Clear (CLR) | Output Enable (OE1, OE2) | Different control schemes mean the devices cannot be directly substituted without redesigning the control logic. |
| Propagation Delay (typical) | ~18 ns at 4.5 V | ~13 ns at 4.5 V | Timing differences can affect setup/hold margins and maximum operating frequency in synchronous systems. |
| Output Drive Current (IOH/IOL) | ±4 mA (standard HC) | ±6 mA (standard HC) | Drive strength affects fan-out and the ability to drive capacitive loads or LEDs directly. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both operate over the same HC voltage range, so power supply compatibility is not a differentiator. |
| Package | SO16 (SOIC-16) | SO20 (SOIC-20) | Different pin counts and footprints prevent direct PCB drop-in replacement. |
| Operating Temperature Range | -40°C to +125°C | -40°C to +125°C | Both meet industrial temperature requirements, so environmental compatibility is equivalent. |
| Pin Count | 16 | 20 | Pin count mismatch means the devices are not pin-to-pin compatible and require different sockets or layouts. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC259D | 74HC244D,653 |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | D-Type, Addressable | Buffer, Non-Inverting |
| Number of Elements | - | 2 |
| Number of Bits per Element | - | 4 |
| Output Type | Standard | 3-State |
| Current - Output High Low | 5.2mA, 5.2mA | 7.8mA, 7.8mA |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Circuit | 1:8 | - |
| Independent Circuits | 1 | - |
| Delay Time - Propagation | 22ns | - |
Frequently asked questions
What are the primary functional differences between the 74HC259D and the 74HC244D,653?
The 74HC259D is an 8-bit addressable latch, meaning it can store one bit of data at a specific address determined by three address inputs. The 74HC244D,653 is an octal non-inverting buffer/line driver with 3-state outputs, designed to drive bus lines or buffer memory address registers without latching data.
Are the 74HC259D and 74HC244D,653 pin-compatible?
No. The 74HC259D is typically supplied in a 16-pin SOIC package, while the 74HC244D,653 is supplied in a 20-pin SOIC package. They have different pin counts and pin functions, so they are not pin-compatible.
Can the 74HC259D and 74HC244D,653 be used interchangeably in a design?
No. They perform fundamentally different logic functions. The 74HC259D latches and decodes addressable data, while the 74HC244D,653 provides non-inverting buffering with 3-state outputs. Substitution requires a complete redesign of the surrounding circuitry.
What are the output drive capabilities of the 74HC244D,653 compared to the 74HC259D?
Both devices are 74HC series CMOS logic. The 74HC244D,653 is specified with standard 74HC output drive of ±4 mA at 5 V, while the 74HC259D also provides standard 74HC output drive of ±4 mA at 5 V. Neither device offers higher bus-drive capability without external buffering.
Do both the 74HC259D and 74HC244D,653 operate at the same supply voltage range?
Yes. Both are 74HC family devices and operate over a supply voltage range of 2.0 V to 6.0 V, with typical operation at 5 V.
Which device is better suited for driving a shared data bus?
The 74HC244D,653 is better suited for driving a shared data bus because it has 3-state outputs that can be placed in a high-impedance state, allowing multiple devices to share the same bus. The 74HC259D has latched outputs without 3-state control, so it is not intended for direct bus multiplexing.
What is the function of the address inputs on the 74HC259D compared to the 74HC244D,653?
The 74HC259D has three address inputs (A0, A1, A2) that select which of the eight latched outputs is updated or read. The 74HC244D,653 has no address inputs; it has two active-low output enable pins (1OE and 2OE) that control the 3-state condition of its eight buffer outputs.
Are the 74HC259D and 74HC244D,653 available in the same package type?
No. The 74HC259D is commonly available in a 16-pin SOIC package. The 74HC244D,653 is commonly available in a 20-pin SOIC package. Package dimensions and pin counts differ, so they are not mechanically interchangeable.