Part A
74HC125D
Toshiba Halbleiter und Speicher
- Lifecycle
- Active
- Stock
- 3803 Stückzahl
- Package
- SOIC-14
- Series
- Logic c Puffer, Treiber, Empfänger, Transceiver
Replacement verdict
Not a drop-in replacement
The 74HC125D and 74HC165D,653 serve fundamentally different logic functions and cannot be used interchangeably in existing designs. The 74HC125D is a quad bus buffer with 3-state outputs, while the 74HC165D,653 is an 8-bit parallel-in/serial-out shift register. Their pinouts, I/O structures, and control signal schemes are entirely incompatible, requiring a complete circuit redesign rather than a direct substitution.
Different logic function
Different output type
Different pinout
Different control interface
Parts at a glance
Part B
74HC165D,653
Nexperia USA Inc.
- Lifecycle
- Active
- Stock
- 9205 Stückzahl
- Series
- Logic-Shift-Register
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC125D | 74HC165D,653 | Why it matters |
|---|---|---|---|
| Logic Function | Quad Buffer/Line Driver with 3-state outputs | 8-bit Parallel-in/Serial-out Shift Register | Defines the core function; these devices perform fundamentally different operations and are not functionally interchangeable. |
| Number of Channels / Bits | 4 channels | 8 bits | Determines how many signals can be handled simultaneously, affecting system architecture and pin count requirements. |
| Output Type | 3-state (tri-state) buffer outputs | Serial data output (with complementary output) | Output configuration dictates how the device interfaces with a bus or downstream logic. |
| Direction / Data Flow | Unidirectional buffering | Parallel load, serial shift out | Data flow direction determines the role in a circuit, such as driving signals versus serializing parallel data. |
| Control Inputs | Output enable (OE) per channel | Shift/Load, Clock, Clock Inhibit | Control pins define how the device is operated and sequenced within a system. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both support the standard HC family voltage range, allowing use in similar logic-level environments. |
| Propagation Delay (typical) | ~11 ns at 4.5 V | ~14 ns at 4.5 V | Affects timing margins in high-speed digital designs. |
| Package | SO14 (SOIC-14) | SO16 (SOIC-16) | Package footprint and pin count must match the PCB layout for physical compatibility. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Both meet industrial temperature requirements, suitable for similar environmental conditions. |
| Pin Count | 14 pins | 16 pins | Different pin counts mean the devices cannot share the same PCB footprint or socket. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC125D | 74HC165D,653 |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | Buffer, Non-Inverting | Shift Register |
| Output Type | 3-State | Complementary |
| Number of Elements | 4 | 1 |
| Number of Bits per Element | 1 | 8 |
| Function | - | Parallel or Serial to Serial |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Base Product Number | - | 74HC165 |
| Current - Output High Low | 7.8mA, 7.8mA | - |
Frequently asked questions
What are the primary functional differences between the 74HC125D and the 74HC165D,653?
The 74HC125D is a quad non-inverting buffer/line driver with 3-state outputs, while the 74HC165D,653 is an 8-bit parallel-in/serial-out shift register. The 74HC125D is used for signal buffering and bus driving, whereas the 74HC165D,653 is used for parallel-to-serial data conversion.
Are the 74HC125D and 74HC165D,653 pin-compatible?
No. The 74HC125D is typically supplied in a 14-pin SOIC package, and the 74HC165D,653 is supplied in a 16-pin SOIC package. They have different pin counts and pin functions, so they are not pin-compatible.
Can the 74HC125D and 74HC165D,653 be used interchangeably in a design?
No. They perform fundamentally different logic functions. The 74HC125D provides buffering with 3-state control, while the 74HC165D,653 performs serial shifting of parallel data. Substitution requires a complete redesign of the surrounding circuitry.
What are the supply voltage ranges for the 74HC125D and 74HC165D,653?
Both devices are 74HC series CMOS logic components and operate over a supply voltage range of 2.0 V to 6.0 V, with typical operation at 5 V.
What is the difference in output drive capability between the 74HC125D and the 74HC165D,653?
The 74HC125D is specified with standard 74HC output drive, typically ±6 mA at 5 V, suitable for driving bus lines. The 74HC165D,653 has standard 74HC outputs intended for logic-level signals rather than high-current bus driving.
Do both the 74HC125D and 74HC165D,653 support 3-state outputs?
The 74HC125D has 3-state outputs controlled by individual output enable pins. The 74HC165D,653 has a serial output that is not 3-state; it provides a standard push-pull CMOS output.
What are the typical applications for the 74HC125D and 74HC165D,653?
The 74HC125D is typically used for bus buffering, signal isolation, and driving transmission lines. The 74HC165D,653 is typically used for input expansion, parallel-to-serial data conversion, and interfacing parallel data to serial buses.
Are the 74HC125D and 74HC165D,653 available in the same package type?
Both devices are available in SOIC packages, but the 74HC125D is a 14-pin SOIC and the 74HC165D,653 is a 16-pin SOIC. The package type is similar, but the pin count and footprint differ.