Part A
74HC157D
東芝電晶體與存儲
- Lifecycle
- Active
- Stock
- 7197 件
- Package
- SOIC-16
- Series
- 邏輯-訊號開關、多工器、解碼器
Replacement verdict
Not a drop-in replacement
The 74HC164D and 74HC157D 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 74HC157D is a quad 2-to-1 non-inverting multiplexer. Their internal architectures, pin functions, and logic operations are fundamentally different, making direct substitution impossible without complete circuit redesign.
Different logic function
Different input configuration
Different output behavior
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 | 74HC164D | 74HC157D | Why it matters |
|---|---|---|---|
| Logic Function | 8-bit serial-in/parallel-out shift register | Quad 2-input multiplexer | The core function determines whether the device can be substituted at all; these parts perform entirely different logic operations. |
| Number of Outputs | 8 parallel outputs | 4 multiplexed outputs | Output count affects how many signals can be driven and the board-level wiring required. |
| Number of Inputs | 2 (data + clock) | 8 data inputs plus select | Input count and type define the interface and the amount of source data the device can accept. |
| Data Direction / Flow | Serial in, parallel out | Parallel in, parallel out (selectable) | Data flow direction determines whether the part can serialize or route signals in a given design. |
| Clock Requirement | Requires clock input | No clock; combinational select | Clocked versus combinational operation changes timing analysis and control logic needs. |
| Select / Control Pins | Clear (reset) pin | Common select and enable pins | Control pins define how the device is configured and reset during operation. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Matching supply ranges allow both parts to operate in the same logic-level environment. |
| Logic Family | HC (High-speed CMOS) | HC (High-speed CMOS) | Same logic family ensures compatible input thresholds and output drive characteristics. |
| Package | SOIC-14 | SOIC-16 | Package footprint and pin count must match the PCB layout for a drop-in replacement. |
| Pin Count | 14 | 16 | Different pin counts mean the parts are not pin-compatible and cannot share the same footprint. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC157D | 74HC164D |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Type | Multiplexer | - |
| Circuit | 4 x 2:1 | - |
| 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 ~ 85°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 functions of the 74HC164D and 74HC157D?
The 74HC164D is an 8-bit serial-in/parallel-out shift register with a synchronous clear input. The 74HC157D is a quad 2-input multiplexer that selects one of two 4-bit data sources based on a common select input.
Can the 74HC164D and 74HC157D be used interchangeably in a circuit?
No. They perform fundamentally different logic functions: the 74HC164D shifts serial data to parallel outputs, while the 74HC157D selects between two parallel data buses. They are not pin-compatible or functionally equivalent.
What are the operating voltage ranges for the 74HC164D and 74HC157D?
Both devices are 74HC-series CMOS logic ICs and typically operate over a supply voltage range of 2.0 V to 6.0 V, as specified in standard 74HC family datasheets.
What package types are commonly available for the 74HC164D and 74HC157D?
Both the 74HC164D and 74HC157D are commonly offered in SOIC-14 (D suffix) packages, as well as other package options such as TSSOP and PDIP depending on the manufacturer.
How many pins do the 74HC164D and 74HC157D have?
Both devices are 14-pin integrated circuits. The 74HC164D uses 14 pins for serial inputs, clock, clear, and eight parallel outputs. The 74HC157D uses 14 pins for two 4-bit data inputs, a select input, and four multiplexed outputs.
What is the difference in output drive capability between the 74HC164D and 74HC157D?
Both are standard 74HC CMOS devices and typically provide symmetrical output drive of approximately ±4 mA at 5 V, as defined by the 74HC family specifications. Neither device is intended for high-current drive applications.
Are the 74HC164D and 74HC157D compatible with 74LS or 74HCT logic levels?
The 74HC164D and 74HC157D are 74HC-series devices with CMOS input thresholds. They can interface with 74LS or 74HCT outputs in many cases, but level compatibility must be verified against the specific datasheet input voltage thresholds (VIH/VIL) and supply voltages used.
What is the maximum operating frequency for the 74HC164D and 74HC157D?
Maximum operating frequency depends on supply voltage and manufacturer. For standard 74HC devices at 5 V, typical maximum clock or propagation frequencies are in the range of 20 MHz to 50 MHz. Always consult the specific manufacturer datasheet for verified limits.