Part A
74HC151D
Toshiba Semiconductor et stockage
- Lifecycle
- Active
- Stock
- 3388 PCS
- Package
- SOIC-16
- Series
- Logique - commutateurs de signaux, multiplexeurs, décodeurs
Replacement verdict
Not a drop-in replacement
The 74HC164D and 74HC151D are not functionally interchangeable despite sharing the same 74HC logic family and SOIC-14 package. The 74HC164D is an 8-bit serial-in/parallel-out shift register, while the 74HC151D is an 8-to-1 multiplexer with complementary outputs. Their internal logic architecture, pin functions, and data flow direction are fundamentally different, making direct substitution impossible without complete circuit redesign.
Different logic function
Different pinout
Different data flow
Different output configuration
Parts at a glance
Part B
74HC164D
Toshiba Semiconductor et stockage
- Lifecycle
- Active
- Stock
- 2726 PCS
- Package
- SOIC-8
- Series
- Logique - Registre à décalage
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC164D | 74HC151D | Why it matters |
|---|---|---|---|
| Logic Function | 8-bit serial-in/parallel-out shift register | 8-input multiplexer (data selector) | The core function differs fundamentally; these devices are not functionally interchangeable in a circuit. |
| Number of Inputs | 2 (serial data A and B) | 8 data inputs plus 3 select inputs | Input count determines how many signals the device can accept and how it is wired into a system. |
| Number of Outputs | 8 parallel outputs (QA-QH) | 1 output (Y) plus complementary output (W) | Output count and type dictate how many loads can be driven and the output configuration. |
| Output Type | Push-pull (standard CMOS) | Push-pull with complementary outputs | Output drive and polarity options affect compatibility with downstream logic and loads. |
| Clock Requirement | Requires clock (CP) for shifting | No clock; combinational selection via select inputs | Sequential versus combinational operation changes timing, control, and application suitability. |
| Control Inputs | Clear (MR) and Clock (CP) | Strobe (G) and Select (S0-S2) | Control pins define how the device is enabled, reset, or configured in a design. |
| Supply Voltage Range | 2.0 V to 6.0 V | 2.0 V to 6.0 V | Matching supply ranges allow both devices to operate in the same logic-level environment. |
| Logic Family | HC (High-speed CMOS) | HC (High-speed CMOS) | Same logic family ensures compatible input/output thresholds and noise margins. |
| Package | SOIC-14 (D suffix) | SOIC-16 (D suffix) | Package footprint and pin count affect PCB layout and physical interchangeability. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Identical temperature ratings ensure both parts suit the same environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC151D | 74HC164D |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Type | Multiplexer | - |
| Circuit | 1 x 8:1 | - |
| Independent Circuits | 1 | - |
| Current - Output High Low | 5.2mA, 5.2mA | - |
| Voltage Supply Source | Single Supply | - |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Logic Type | - | Shift Register |
| Output Type | - | Push-Pull |
| Number of Elements | - | 1 |
| Number of Bits per Element | - | 8 |
| Function | - | Serial to Parallel |
Frequently asked questions
What are the primary functional differences between the 74HC164D and the 74HC151D?
The 74HC164D is an 8-bit serial-in/parallel-out shift register, while the 74HC151D is an 8-to-1 multiplexer. The 74HC164D converts serial data into parallel outputs, whereas the 74HC151D selects one of eight data inputs based on a 3-bit select code and routes it to a single output.
Are the 74HC164D and 74HC151D pin-compatible?
No. The 74HC164D is typically supplied in a 14-pin SOIC package, and the 74HC151D is typically supplied in a 16-pin SOIC package. They have different pin counts and pin functions, so they are not pin-compatible.
Can the 74HC164D and 74HC151D be used together in the same design?
Yes. They perform different logic functions and can be used together. For example, a 74HC164D can expand the number of parallel outputs from a microcontroller, and a 74HC151D can multiplex multiple signals into a single input line.
What is the difference in input and output configuration between the 74HC164D and the 74HC151D?
The 74HC164D has two serial data inputs (A and B), a clock input, a clear input, and eight parallel outputs (QA through QH). The 74HC151D has eight data inputs (D0 through D7), three select inputs (S0, S1, S2), an enable input, and one output (Y) plus its complement (W).
Do the 74HC164D and 74HC151D operate at the same supply voltage and logic levels?
Yes. Both are 74HC-series CMOS devices and typically operate from a 2.0 V to 6.0 V supply. Their input and output logic levels are compatible with standard CMOS and TTL-level logic when used within the specified supply voltage range.
Which device is better for serial-to-parallel data conversion?
The 74HC164D is the correct choice for serial-to-parallel conversion because it is specifically designed as a serial-in/parallel-out shift register. The 74HC151D cannot perform serial-to-parallel conversion because it is a multiplexer, not a shift register.
Which device is better for selecting one of eight digital signals?
The 74HC151D is the correct choice for selecting one of eight digital signals because it is an 8-to-1 multiplexer. The 74HC164D cannot perform this function because it has no select inputs or multiplexer architecture.
Are the 74HC164D and 74HC151D interchangeable in existing designs?
No. They are not functionally or pin-compatible. Replacing one with the other would require a complete redesign of the surrounding circuit, including pin assignments, control signals, and logic function.