Part A
74HC151D
Toshiba Semiconductor và lưu trữ
- Lifecycle
- Active
- Stock
- 3388 PCS
- Package
- SOIC-16
- Series
- Logic - Signal Switches, Multiplexers, Decoders
Replacement verdict
Not a drop-in replacement
The 74HC126D and 74HC151D serve fundamentally different logic functions and cannot be used interchangeably in existing designs. The 74HC126D provides four independent tri-state non-inverting buffers with individual output enable control, while the 74HC151D is an 8-to-1 multiplexer with complementary outputs and a single active-low enable. Although both share the same SOIC-16 package and 74HC CMOS family characteristics, their internal signal routing, pin assignments, and control logic differ entirely, making direct substitution impossible without circuit redesign.
Different logic function
Different output type
Different control interface
Different pin assignment
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC126D | 74HC151D | Why it matters |
|---|---|---|---|
| Function | Quad buffer/line driver with 3-state outputs | 8-input multiplexer with complementary outputs | The core logic function differs, so these devices are not functionally interchangeable in a circuit. |
| Logic Type | Non-inverting buffer with enable | Data selector/multiplexer | Different logic types perform entirely different signal routing and selection tasks. |
| Number of Channels | 4 | 1 multiplexer (8 inputs to 1 output) | Channel count determines how many independent signals can be handled simultaneously. |
| Output Type | 3-state | Push-pull (complementary) | 3-state outputs allow bus sharing, while push-pull outputs cannot be tied together directly. |
| Number of Pins | 14 | 16 | Different pin counts mean different package footprints and PCB layouts. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both support the same HC-family supply range, allowing use in similar logic-level systems. |
| Propagation Delay | Typically 11 ns at 4.5 V | Typically 14 ns at 4.5 V | Propagation delay affects maximum operating speed and timing margins in digital designs. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Both devices are rated for industrial temperature ranges, suitable for harsh environments. |
| Package Type | SO14 (Small Outline) | SO16 (Small Outline) | Different package sizes require different PCB footprints and cannot be drop-in replaced. |
| Enable/Select Inputs | 4 individual output enable pins | 3 select inputs plus 1 enable input | Control input configuration determines how the device is addressed and activated in a system. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC151D | 74HC126D |
|---|---|---|
| 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 | 7.8mA, 7.8mA |
| Voltage Supply Source | Single Supply | - |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Logic Type | - | Buffer, Non-Inverting |
| Number of Elements | - | 4 |
| Number of Bits per Element | - | 1 |
| Output Type | - | 3-State |
Frequently asked questions
What are the primary functional differences between the 74HC126D and the 74HC151D?
The 74HC126D is a quad non-inverting 3-state buffer with four independent channels, each controlled by its own active-high output enable pin. The 74HC151D is an 8-to-1 multiplexer that selects one of eight data inputs based on a 3-bit binary select code and provides a single non-inverting output, along with a complementary output on some variants. They serve fundamentally different logic functions and are not interchangeable.
Can the 74HC126D and 74HC151D be used interchangeably in a circuit design?
No. The 74HC126D provides four independent 3-state buffers, while the 74HC151D is a single 8-to-1 multiplexer. Their pinouts, logic functions, and control schemes differ completely, so direct substitution is not possible without redesigning the surrounding circuitry.
Do the 74HC126D and 74HC151D share the same package and pinout?
Both devices are commonly offered in a 16-pin SOIC package (the "D" suffix typically denotes SOIC). However, their pin assignments are different because they implement different logic functions. The 74HC126D uses pins for four buffer inputs, four buffer outputs, and four output-enable controls, while the 74HC151D uses pins for eight data inputs, three select inputs, one or two outputs, and an enable input.
What are the typical operating voltage and logic family characteristics of these devices?
Both the 74HC126D and 74HC151D belong to the 74HC high-speed CMOS logic family. They typically operate over a supply voltage range of 2.0 V to 6.0 V, with standard CMOS input thresholds and rail-to-rail output swing. Exact limits should be confirmed from the respective manufacturer datasheets.
Which device is suitable for multiplexing multiple digital signals onto a single line?
The 74HC151D is the appropriate choice for multiplexing, as it is an 8-to-1 multiplexer designed to select one of eight digital inputs and route it to a single output. The 74HC126D cannot perform multiplexing on its own; it only provides buffering and 3-state isolation for up to four independent signals.
Which device is suitable for bus isolation or bidirectional bus interfacing?
The 74HC126D is suitable for bus isolation and bus interfacing because its 3-state outputs can be placed in a high-impedance state, effectively disconnecting the buffer from the bus. The 74HC151D does not have 3-state outputs and therefore cannot provide high-impedance bus isolation.
Are the output drive capabilities of the 74HC126D and 74HC151D the same?
Both devices are 74HC CMOS logic and typically provide similar output drive currents, commonly specified as ±4 mA or ±5.2 mA at 4.5 V depending on the manufacturer and test conditions. However, designers should always verify the exact IOH and IOL ratings from the specific manufacturer datasheet for each part.
Can the 74HC151D be used to replace multiple 74HC126D buffers in a signal selection application?
No. The 74HC151D selects one of eight inputs based on a binary address, whereas the 74HC126D independently buffers and enables four separate signals. Replacing multiple 74HC126D buffers with a single 74HC151D would change the circuit topology, control logic, and signal routing, and would not preserve the original independent enable functionality.