Part A
74HC123D
パナソニック電子部品
- Lifecycle
- Active
- Stock
- 3320 個数
- Package
- SOIC-16
- Series
- ロジック - マルチバイブレータ
Replacement verdict
Not a drop-in replacement
The 74HC123D and 74HC165D,653 are not functionally interchangeable. The 74HC123D is a dual retriggerable monostable multivibrator with timing-dependent outputs, while the 74HC165D,653 is an 8-bit parallel-in/serial-out shift register. Their core logic functions, pin configurations, and signal flow architectures are fundamentally different, making direct substitution impossible without complete circuit redesign.
Different logic function
Different pinout
Different output type
Different signal flow
Parts at a glance
Part B
74HC165D,653
ネクスペリアUSA株式会社
- Lifecycle
- Active
- Stock
- 9205 個数
- Series
- ロジック - シフトレジスタ
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC123D | 74HC165D,653 | Why it matters |
|---|---|---|---|
| Logic Function | Dual Retriggerable Monostable Multivibrator | 8-bit Parallel-in/Serial-out Shift Register | The core function differs fundamentally; one generates timed pulses while the other converts parallel data to serial, so they are not functionally interchangeable. |
| Number of Channels / Bits | 2 monostable channels | 8-bit shift register | Channel/bit count determines how many independent signals can be processed, directly affecting circuit capacity and design. |
| Output Type | Complementary (Q and Q-bar) per channel | Serial data output (Q and Q-bar) | Output configuration dictates how the device interfaces with downstream logic and whether inverted signals are available. |
| Input Type | Trigger inputs (A, B) with retrigger capability | Parallel (D0-D7) and serial (DS) inputs with clock | Input structure determines the control signals and data-loading method required for proper operation. |
| Propagation Delay (typical at 5V) | Approximately 20 ns | Approximately 14 ns | Propagation delay affects maximum operating frequency and timing margins in synchronous systems. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both support the standard HC-family supply range, allowing use in 3.3 V and 5 V logic systems. |
| Package | SO14 (SOIC-14) | SO16 (SOIC-16) | Different pin counts and package sizes prevent direct drop-in replacement on the same PCB footprint. |
| Pin Count | 14 | 16 | Pin count mismatch means the devices cannot share the same socket or land pattern. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Both meet industrial temperature requirements, suitable for harsh-environment applications. |
| Retriggerable | Yes | Not applicable | Retriggerability allows pulse extension without external circuitry, a feature unique to the monostable device. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC123D | 74HC165D,653 |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | Monostable | Shift Register |
| Output Type | - | Complementary |
| Number of Elements | - | 1 |
| Number of Bits per Element | - | 8 |
| Function | - | Parallel or Serial to Serial |
| Voltage - Supply | 2 V ~ 6 V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Base Product Number | - | 74HC165 |
| Independent Circuits | 2 | - |
| Schmitt Trigger Input | Yes | - |
| Propagation Delay | 40 ns | - |
| Current - Output High Low | 5.2mA, 5.2mA | - |
Frequently asked questions
What are the primary functions of the 74HC123D and the 74HC165D,653?
The 74HC123D is a dual retriggerable monostable multivibrator that generates a single output pulse of a specified width for each input trigger. The 74HC165D,653 is an 8-bit parallel-in/serial-out shift register used to convert parallel data into a serial data stream.
Can the 74HC123D and 74HC165D,653 be used interchangeably in a circuit design?
No. They perform fundamentally different logic functions. The 74HC123D is a timing device for pulse generation, while the 74HC165D,653 is a data conversion device for serialization. They are not pin-compatible or functionally equivalent.
What are the package types for the 74HC123D and the 74HC165D,653?
The 74HC123D is typically supplied in a 16-pin SOIC package. The 74HC165D,653 is supplied in a 16-pin SOIC package as well, but the internal pin functions and electrical characteristics differ between the two devices.
What supply voltage range do the 74HC123D and 74HC165D,653 support?
Both devices are members of the 74HC logic family and operate over a recommended supply voltage range of 2.0 V to 6.0 V, with typical operation at 5.0 V.
How does the output behavior differ between the 74HC123D and the 74HC165D,653?
The 74HC123D provides complementary pulse outputs (Q and Q-bar) whose pulse width is set by an external resistor and capacitor. The 74HC165D,653 provides a single serial data output (Q7) and an optional complementary serial output (Q7-bar) that shift out stored parallel data on each clock edge.
Are the 74HC123D and 74HC165D,653 compatible with standard CMOS logic levels?
Yes. Both devices are high-speed CMOS (HC) logic components and are compatible with standard CMOS input and output voltage levels when operated within their specified supply voltage range.
What are typical applications for the 74HC123D versus the 74HC165D,653?
The 74HC123D is commonly used for pulse shaping, timing delays, and debouncing circuits. The 74HC165D,653 is typically used for input expansion, parallel-to-serial data conversion, and interfacing parallel data sources to serial communication buses.