Part A
74HC151D
Toshiba Halbleiter und Speicher
- Lifecycle
- Active
- Stock
- 3388 Stückzahl
- Package
- SOIC-16
- Series
- Logic.Signal Schalter, Multiplexer, Decoder
Replacement verdict
Not a drop-in replacement
The 74HC151D and 74HC165D,653 are functionally distinct logic ICs that cannot serve as substitutes for one another. The 74HC151D is an 8-to-1 multiplexer with complementary outputs, while the 74HC165D,653 is an 8-bit parallel-in/serial-out shift register. Their differing logic functions, output configurations, pin assignments, and data flow directions make direct replacement impossible without redesigning the surrounding circuit.
Different logic function
Different output type
Different pin assignment
Different data direction
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 | 74HC151D | 74HC165D,653 | Why it matters |
|---|---|---|---|
| Logic Function | 8-input multiplexer (data selector) | 8-bit parallel-in/serial-out shift register | Defines the core operation; these devices perform fundamentally different functions and are not direct substitutes. |
| Number of Select/Control Inputs | 3 select inputs (S0-S2) plus strobe | 1 shift/load control plus clock and clock inhibit | Determines how the device is addressed or controlled within a system. |
| Data Inputs | 8 data inputs (I0-I7) | 8 parallel data inputs (D0-D7) plus serial input | Affects how many signals can be handled and the wiring required in a design. |
| Output Type | Single complementary output (Y and Y-bar) | Serial output (Q) and complementary serial output (Q-bar) | Determines the signal format presented to downstream circuitry. |
| Operating Mode | Combinational selection of one of eight inputs | Synchronous parallel load or serial shift | Distinguishes combinational logic behavior from sequential clocked behavior. |
| Supply Voltage Range | 2.0 V to 6.0 V | 2.0 V to 6.0 V | Both support standard HC-family logic levels, allowing use in similar supply environments. |
| Logic Family | 74HC (high-speed CMOS) | 74HC (high-speed CMOS) | Same family implies compatible input/output thresholds and noise margins. |
| Package | SO16 (SOIC-16) | SO16 (SOIC-16) | Identical footprint allows drop-in board placement even though functions differ. |
| Pin Count | 16 | 16 | Same pin count simplifies PCB layout considerations. |
| Typical Propagation Delay | Approximately 14 ns at 4.5 V | Approximately 14 ns at 4.5 V (clock to output) | Timing performance affects maximum operating frequency and system speed. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC151D | 74HC165D,653 |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | - | Shift Register |
| Output Type | - | Complementary |
| Number of Elements | - | 1 |
| Number of Bits per Element | - | 8 |
| Function | - | Parallel or Serial to Serial |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Base Product Number | - | 74HC165 |
| Type | Multiplexer | - |
| Circuit | 1 x 8:1 | - |
| Independent Circuits | 1 | - |
| Current - Output High Low | 5.2mA, 5.2mA | - |
| Voltage Supply Source | Single Supply | - |
Frequently asked questions
What are the primary functional differences between the 74HC151D and the 74HC165D,653?
The 74HC151D is an 8-input multiplexer that selects one of eight data inputs based on a 3-bit select code and routes it to a single output. The 74HC165D,653 is an 8-bit parallel-in/serial-out shift register that loads eight parallel inputs and shifts the data out serially. They perform fundamentally different logic functions and are not interchangeable.
Are the 74HC151D and 74HC165D,653 pin-compatible?
No. The 74HC151D is typically supplied in a 16-pin SOIC package with a pinout dedicated to multiplexer functions (eight data inputs, three select inputs, enable, and complementary outputs). The 74HC165D,653 is supplied in a 16-pin SOIC package with a pinout dedicated to shift-register functions (eight parallel inputs, serial input, clock, shift/load, and serial output). The pin functions and assignments differ, so they cannot be used as drop-in replacements for each other.
Can the 74HC151D and 74HC165D,653 operate from the same supply voltage range?
Yes. Both devices are members of the 74HC logic family and are specified for a supply voltage range of 2.0 V to 6.0 V, with typical operation at 5.0 V. This common supply range allows them to be used in the same logic system, provided the differing logic functions are accounted for in the design.
What is the maximum clock frequency for the 74HC165D,653, and does the 74HC151D have an equivalent clock specification?
The 74HC165D,653 shift register has a maximum clock frequency specified in its datasheet, typically in the range of 20 MHz to 30 MHz at 5 V supply, depending on the manufacturer and load conditions. The 74HC151D multiplexer is a combinational logic device and does not have a clock input or a clock frequency specification; its propagation delay and select-to-output timing are the relevant dynamic parameters instead.
Which device is suitable for serializing parallel data, and which is suitable for data selection?
The 74HC165D,653 is the appropriate choice for serializing parallel data because it is an 8-bit parallel-in/serial-out shift register. The 74HC151D is the appropriate choice for data selection because it is an 8-to-1 multiplexer that selects one of eight inputs based on a 3-bit select code.
Do both devices support the same output drive capability?
Both devices are 74HC-family parts and typically provide standard CMOS output drive, which is commonly specified as ±4 mA at 5 V supply for balanced drive. However, exact drive current ratings can vary by manufacturer, so the specific datasheet for each part number should be consulted to confirm the output current specifications.
Are the 74HC151D and 74HC165D,653 available in the same package type?
Both are commonly available in a 16-pin SOIC package, which is indicated by the "D" suffix in the 74HC151D and the "D" in the 74HC165D,653 ordering code. However, despite the shared package style and pin count, the internal die and pin functions differ, so they are not electrically or functionally interchangeable.
Can the 74HC151D and 74HC165D,653 be used together in a single design?
Yes. Because both are 74HC-family devices with compatible supply voltage and logic level specifications, they can be used together in the same system. For example, the 74HC151D can select among multiple data sources, and the 74HC165D,653 can serialize the selected or other parallel data for transmission to a microcontroller or another serial interface.