Part A
74HC157D
Toshiba Semiconductor and Storage
- Lifecycle
- Active
- Stock
- 7197 PCS
- Package
- SOIC-16
- Series
- Logic - Signal Switches, Multiplexers, Decoders
Replacement verdict
Not a drop-in replacement
The 74HC151D and 74HC157D are not functionally interchangeable despite sharing the same 74HC logic family and SOIC-16 package. The 74HC151D is an 8-to-1 multiplexer with single-ended data selection and complementary outputs, while the 74HC157D is a quad 2-to-1 multiplexer with non-inverting outputs and a common select input. Their internal signal routing, channel count, output configuration, and pin function assignments differ fundamentally, so substituting one for the other requires circuit redesign rather than a direct drop-in replacement.
Different multiplexer function
Different channel count
Different output configuration
Different pin function 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 | 74HC151D | 74HC157D | Why it matters |
|---|---|---|---|
| Logic Function | 8-to-1 multiplexer (data selector) | Quad 2-to-1 multiplexer (data selector) | Defines the core function; these are not functionally interchangeable since one selects 1 of 8 inputs while the other selects 1 of 2 inputs across four channels. |
| Number of Channels | 1 | 4 | Determines how many independent signals can be multiplexed simultaneously, directly affecting circuit architecture. |
| Number of Inputs per Channel | 8 | 2 | Sets the selection depth; a wider input count allows more data sources to share a single output line. |
| Select Lines | 3 (A, B, C) | 1 (common select for all 4 channels) | Determines the control interface and how many address bits are needed to route data. |
| Output Type | Complementary outputs (Y and W) | Non-inverting outputs (Y) | Affects whether both true and inverted signals are available, influencing downstream logic design. |
| Enable/Strobe Control | Active-LOW strobe (E) forces Y LOW and W HIGH | Active-LOW enable (E) forces all outputs LOW | Determines the default output state when disabled, which is critical for bus sharing and power-up behavior. |
| Supply Voltage Range | 2.0 V to 6.0 V | 2.0 V to 6.0 V | Both support the standard HC-family supply range, allowing use in 3.3 V and 5 V systems. |
| Package | SO16 (SOIC-16) | SO16 (SOIC-16) | Identical footprint allows drop-in PCB compatibility without layout changes. |
| Logic Family | 74HC (high-speed CMOS) | 74HC (high-speed CMOS) | Same family ensures compatible input thresholds, output drive, and noise margins. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Identical temperature ratings confirm suitability for the same industrial and automotive environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC157D | 74HC151D |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Type | Multiplexer | Multiplexer |
| Circuit | 4 x 2:1 | 1 x 8:1 |
| Independent Circuits | 1 | 1 |
| Current - Output High Low | 5.2mA, 5.2mA | 5.2mA, 5.2mA |
| Voltage Supply Source | Single Supply | Single Supply |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the primary functional differences between the 74HC151D and the 74HC157D?
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 both true and complementary outputs. The 74HC157D contains four independent 2-to-1 multiplexers with a common select input and a common enable input, each providing a single non-inverted output.
Are the 74HC151D and 74HC157D pin-compatible?
No. The 74HC151D is typically supplied in a 16-pin SOIC package with a specific pinout for 8 data inputs, 3 select inputs, enable, and true/complementary outputs. The 74HC157D is also typically a 16-pin SOIC but has a different pinout for four 2-to-1 multiplexer channels, a common select, and a common enable. They are not pin-to-pin replacements.
Can the 74HC151D be used as a direct substitute for the 74HC157D in an existing design?
No. The devices have different logic functions, input/output configurations, and pin assignments. A direct substitution would require redesign of the surrounding circuitry and is not supported by manufacturer datasheets.
What are the supply voltage and logic family specifications for both devices?
Both the 74HC151D and 74HC157D are members of 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 74HC input and output characteristics as specified in their respective manufacturer datasheets.
How many select inputs does each device have?
The 74HC151D has three select inputs (S0, S1, S2) to address eight data channels. The 74HC157D has one common select input (S) that controls all four 2-to-1 multiplexers simultaneously.
Do both devices provide complementary outputs?
No. The 74HC151D provides both a true output (Y) and a complementary output (W). The 74HC157D provides only non-inverted outputs (one per multiplexer); it does not have complementary outputs.
What is the typical propagation delay for these devices?
Propagation delay depends on supply voltage, load capacitance, and temperature. For standard 74HC devices at 5 V and 25°C, typical propagation delays are in the range of 10 ns to 20 ns. Refer to the specific manufacturer datasheet for guaranteed limits and test conditions.
Are the 74HC151D and 74HC157D available in the same package types?
Both are commonly available in 16-pin SOIC (D suffix) packages, among other package options. However, package compatibility does not imply functional or pin compatibility; the internal die and pin assignments differ.