Part A
74HC157D
Toshiba Semiconductor và lưu trữ
- Lifecycle
- Active
- Stock
- 7197 PCS
- Package
- SOIC-16
- Series
- Logic - Signal Switches, Multiplexers, Decoders
Replacement verdict
Not a drop-in replacement
The 74HC157D and 74HC165D,653 are not functionally interchangeable despite sharing the same 74HC logic family and SOIC-16 package. The 74HC157D is a quad 2-input multiplexer that selects between two data inputs per channel, while the 74HC165D,653 is an 8-bit parallel-in/serial-out shift register. Their internal logic functions, pin assignments, and signal flow architectures are fundamentally different, making direct substitution impossible without circuit redesign.
Different logic function
Different pin assignment
Different data flow direction
Different input/output configuration
Parts at a glance
Part B
74HC165D,653
Nexperia Hoa Kỳ Inc.
- Lifecycle
- Active
- Stock
- 9205 PCS
- Series
- Logic - Shift Registers
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC157D | 74HC165D,653 | Why it matters |
|---|---|---|---|
| Logic Function | Quad 2-input multiplexer | 8-bit parallel-in/serial-out shift register | Defines the core function; these devices are not functionally interchangeable as they perform entirely different logic operations. |
| Number of Inputs | 8 data inputs (2 per multiplexer x 4) | 9 inputs (8 parallel data + 1 serial) | Input count determines how many signals the device can accept and process simultaneously. |
| Number of Outputs | 4 outputs | 2 outputs (Q and Q-bar serial) | Output configuration affects how the device interfaces with downstream circuitry. |
| Output Type | Parallel (non-inverting) | Serial (Q and complementary Q-bar) | Determines whether data is delivered simultaneously or sequentially, impacting system architecture. |
| Data Flow Direction | Selects between two inputs to one output | Parallel load to serial shift out | Dictates the signal routing behavior and the application suitability of each device. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both operate over the standard HC-family voltage range, allowing use in similar logic-level environments. |
| Logic Family | 74HC (high-speed CMOS) | 74HC (high-speed CMOS) | Same logic family ensures compatible input/output thresholds and noise margins when interfacing. |
| Package Type | SO16 (SOIC-16) | SO16 (SOIC-16) | Identical package allows the same PCB footprint, though electrical function still differs. |
| Pin Count | 16 | 16 | Same pin count simplifies board layout considerations but pin functions are not equivalent. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Both support industrial temperature ranges, but this does not compensate for their different logic functions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC157D | 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 ~ 85°C | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Base Product Number | - | 74HC165 |
| Type | Multiplexer | - |
| Circuit | 4 x 2:1 | - |
| 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 74HC157D and the 74HC165D,653?
The 74HC157D is a quad 2-input multiplexer that selects one of two 4-bit data sources based on a common select input. The 74HC165D,653 is an 8-bit parallel-in/serial-out shift register used to convert parallel data to serial data. They perform fundamentally different logic functions and are not interchangeable.
Are the 74HC157D and 74HC165D,653 pin-compatible?
No. The 74HC157D is typically supplied in a 16-pin SOIC package with multiplexer input/output pin assignments, while the 74HC165D,653 is supplied in a 16-pin SOIC package with shift register control, parallel input, and serial output pin assignments. Even where package dimensions match, the pin functions differ, so they cannot be used as drop-in replacements.
Can the 74HC157D 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 nominal supply voltage range of 2.0 V to 6.0 V, with typical operation at 5.0 V. This shared supply range allows them to be used in the same logic system, provided their individual timing and drive requirements are respected.
Which device is suitable for serializing parallel data onto a single line?
The 74HC165D,653 is the correct choice for parallel-to-serial conversion. It loads 8 bits of parallel data and shifts them out serially under clock control. The 74HC157D cannot perform serialization because it only selects between two parallel 4-bit data paths.
Which device is suitable for selecting between two 4-bit data buses?
The 74HC157D is designed for 2-to-1 multiplexing of 4-bit data. It routes one of two 4-bit inputs to the outputs based on a select signal. The 74HC165D,653 does not provide multiplexing of parallel data buses; it is intended for parallel-in/serial-out shifting.
Do both devices have the same output drive capability?
Both are 74HC-family CMOS devices and typically provide symmetrical output drive specified in the datasheet, commonly ±4 mA at 5 V for standard HC outputs. However, exact drive current, propagation delay, and input capacitance should be verified from the specific manufacturer datasheet for each part number, as these parameters can vary slightly between suppliers.
Can the 74HC157D and 74HC165D,653 be used together in the same design?
Yes. Because both are 74HC-family devices with compatible supply voltage and logic level specifications, they can be used together. A common example is using the 74HC157D to multiplex data sources and the 74HC165D,653 to serialize the selected data for transmission to a microcontroller or other serial interface.
Are the 74HC157D and 74HC165D,653 available in the same package type?
Both part numbers are commonly available in a 16-pin SOIC package, among other package options. However, the package alone does not determine compatibility; the internal logic function and pin assignment differ, so the correct device must be selected based on the required function, not just the package footprint.