Part A
74HC259D
Toshiba Semiconductor và lưu trữ
- Lifecycle
- Active
- Stock
- 7207 PCS
- Package
- SOIC-20
- Series
- Logic - Latches
Replacement verdict
Not a drop-in replacement
The 74HC259D and 74HC273D,652 are functionally distinct logic ICs that cannot serve as substitutes for one another. The 74HC259D is an 8-bit addressable latch with decoder and demultiplexer functions, while the 74HC273D,652 is an octal D-type flip-flop with a common clock and master reset. Their differing logic functions, input/output architectures, and pinout configurations make direct replacement infeasible without significant circuit redesign.
Different logic function
Different output type
Different pinout
Different clock architecture
Parts at a glance
Part B
74HC273D,652
NXP bán dẫn
- Lifecycle
- Active
- Stock
- 6122 PCS
- Series
- Logic - Flip Flops
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 | 74HC273D,652 | Why it matters |
|---|---|---|---|
| Logic Function | 8-bit addressable latch | Octal D-type flip-flop | Defines the core behavior; these devices are not functionally interchangeable since one latches addressed bits while the other registers all bits on a clock edge. |
| Number of Bits / Channels | 8 (addressable, 1 of 8) | 8 (parallel) | Both store 8 bits, but the 74HC259D writes one selected bit at a time, whereas the 74HC273D,652 updates all 8 outputs simultaneously. |
| Output Type | Active-low parallel outputs (with active-low reset) | Non-inverting parallel outputs | Output polarity affects system logic levels and whether external inversion is required when substituting one device for the other. |
| Clock / Latch Control | Address inputs (A0-A2) select latch; no clock edge | Common clock (CP) edge-triggered | The control mechanism determines timing and how data is captured; addressable latching versus edge-triggered clocking changes the driving logic. |
| Reset / Clear | Asynchronous active-low reset (MR) | Asynchronous active-low clear (MR) | Both provide asynchronous reset, but the reset affects all outputs in the 74HC273D,652 while the 74HC259D reset clears the addressed latch state. |
| Propagation Delay (typical at 5 V) | Approximately 15 ns | Approximately 13 ns | Timing differences can affect setup/hold margins and maximum operating frequency in synchronous designs. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both support standard HC-family supply voltages, so power-supply compatibility is maintained. |
| Package | SO16 (SOIC-16) | SO20 (SOIC-20) | Different pin counts and footprints prevent direct drop-in replacement without PCB layout changes. |
| Pin Count | 16 | 20 | Pin count mismatch means the devices are not pin-compatible and cannot be swapped in the same socket. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Both meet industrial temperature requirements, so environmental compatibility is equivalent. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC259D | 74HC273D,652 |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | 74HC | Bulk |
| Function | - | Active |
| Part Status | Active | - |
| Logic Type | D-Type, Addressable | - |
| Circuit | 1:8 | - |
| Output Type | Standard | - |
| Voltage - Supply | 2V ~ 6V | - |
| Independent Circuits | 1 | - |
| Delay Time - Propagation | 22ns | - |
| Current - Output High Low | 5.2mA, 5.2mA | - |
| Operating Temperature | -40°C ~ 125°C | - |
| Mounting Type | Surface Mount | - |
Frequently asked questions
What are the primary functional differences between the 74HC259D and the 74HC273D,652?
The 74HC259D is an 8-bit addressable latch. It can store one bit of data at a time, selected by a 3-bit address, and also provides a 1-of-8 demultiplexing function. The 74HC273D,652 is an 8-bit D-type flip-flop with a common clock and a common asynchronous reset. It stores all 8 bits simultaneously on a clock edge.
Are the 74HC259D and 74HC273D,652 pin-compatible?
No. The 74HC259D is typically supplied in a 16-pin SOIC package, while the 74HC273D,652 is supplied in a 20-pin SOIC package. They have different pin counts and pinouts, so they are not drop-in replacements.
Can the 74HC259D and 74HC273D,652 operate from the same supply voltage range?
Yes. Both devices are 74HC-family CMOS logic parts and operate over a supply voltage range of 2.0 V to 6.0 V, with typical operation at 5.0 V.
How does the data loading mechanism differ between the 74HC259D and the 74HC273D,652?
The 74HC259D loads one selected output at a time based on the address inputs A0, A1, and A2 when the enable input is active. The 74HC273D,652 loads all eight outputs simultaneously from the D inputs on the rising edge of the common clock signal.
Do both devices provide an asynchronous reset function?
No. The 74HC273D,652 includes an asynchronous master reset (MR) that clears all eight outputs to the low state regardless of the clock. The 74HC259D does not have a global asynchronous reset; its outputs are controlled by the address, enable, and data inputs.
Which device is more suitable for demultiplexing a single data line to one of eight outputs?
The 74HC259D is more suitable because it integrates an 8-bit addressable latch with a 1-of-8 decoder/demultiplexer function. The 74HC273D,652 is an 8-bit register and does not provide addressable output selection.
Are the 74HC259D and 74HC273D,652 interchangeable in an existing design?
No. They differ in function, pin count, package, and control logic. Direct substitution is not possible without redesigning the circuit and validating timing, pinout, and logic requirements against the manufacturer datasheets.