Part A
74HC139D
Toshiba Semiconductor và lưu trữ
- Lifecycle
- Active
- Stock
- 4290 PCS
- Package
- SOIC-16
- Series
- Logic - Signal Switches, Multiplexers, Decoders
Replacement verdict
Not a drop-in replacement
The 74HC139D and 74HC165D,653 are functionally unrelated logic ICs and cannot serve as substitutes for one another. The 74HC139D is a dual 2-to-4 line decoder/demultiplexer, while the 74HC165D,653 is an 8-bit parallel-in/serial-out shift register. Their differing logic functions, pin configurations, and signal flow directions make direct replacement impossible without complete circuit redesign.
Different logic function
Different pinout
Different signal 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 | 74HC139D | 74HC165D,653 | Why it matters |
|---|---|---|---|
| Logic Function | Dual 2-to-4 line decoder/demultiplexer | 8-bit parallel-in/serial-out shift register | The core function differs fundamentally; one decodes addresses while the other shifts data, so they are not functionally interchangeable. |
| Number of Pins | 16 | 16 | Pin count affects package compatibility and PCB footprint, though both share the same count here. |
| Package Type | SO16 (SOIC-16) | SO16 (SOIC-16) | Package type determines mounting style and thermal characteristics; identical packages ease board-level substitution. |
| Supply Voltage Range | 2.0 V to 6.0 V | 2.0 V to 6.0 V | Operating voltage range must match the system supply to ensure reliable logic levels and avoid damage. |
| Output Type | Active LOW decoded outputs | Serial output (Q7) and complementary output (Q7̄) | Output configuration dictates how the device interfaces with downstream logic and whether inversion is required. |
| Number of Inputs | 2 address inputs plus 2 enable inputs | 8 parallel data inputs plus clock, shift/load, and inhibit | Input count and type determine the control signals and data paths required in a design. |
| Propagation Delay (typical) | ~14 ns at 4.5 V | ~14 ns at 4.5 V | Propagation delay affects timing margins and maximum operating frequency in synchronous systems. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Temperature range ensures the device operates reliably in the intended environmental conditions. |
| Logic Family | 74HC (High-speed CMOS) | 74HC (High-speed CMOS) | Logic family compatibility ensures consistent input thresholds, output drive, and noise immunity across the design. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC139D | 74HC165D,653 |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Obsolete | 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 | Decoder/Demultiplexer | - |
| Circuit | 1 x 2:4 | - |
| Independent Circuits | 2 | - |
| Current - Output High Low | 5.2mA, 5.2mA | - |
| Voltage Supply Source | Single Supply | - |
Frequently asked questions
What are the primary functional differences between the 74HC139D and the 74HC165D,653?
The 74HC139D is a dual 2-to-4 line decoder/demultiplexer, while the 74HC165D,653 is an 8-bit parallel-in/serial-out shift register. The 74HC139D routes one of four outputs based on a 2-bit binary address, whereas the 74HC165D,653 loads eight parallel bits and shifts them out serially.
Are the 74HC139D and 74HC165D,653 pin-to-pin compatible?
No. The 74HC139D is typically supplied in a 16-pin SOIC package, and the 74HC165D,653 is supplied in a 16-pin SOIC package as well, but their pin functions differ completely. The 74HC139D has address inputs, enable inputs, and four decoded outputs, while the 74HC165D,653 has parallel data inputs, serial input, clock, shift/load, and serial output pins.
Can the 74HC139D be used as a drop-in replacement for the 74HC165D,653?
No. The two devices perform entirely different logic functions. The 74HC139D is a decoder/demultiplexer, and the 74HC165D,653 is a shift register. Substitution requires a complete redesign of the surrounding circuit and cannot be done as a direct drop-in replacement.
What are the operating voltage and logic family specifications for both devices?
Both the 74HC139D and the 74HC165D,653 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 74HC input and output voltage thresholds. Exact limits should be confirmed in the respective manufacturer datasheets.
What is the function of the 74HC139D in a digital system?
The 74HC139D contains two independent 2-to-4 line decoders. Each decoder accepts a 2-bit address and an active-low enable input, then activates one of four mutually exclusive outputs. It is commonly used for address decoding, memory chip selection, and demultiplexing applications.
What is the function of the 74HC165D,653 in a digital system?
The 74HC165D,653 is an 8-bit parallel-in/serial-out shift register. It can load eight parallel data bits asynchronously and then shift them out serially under clock control. It is commonly used for input expansion, parallel-to-serial data conversion, and reducing the number of microcontroller I/O pins required.
Do both devices support the same clock frequency and propagation delay characteristics?
No. The 74HC139D is a combinational logic decoder and does not have a clock input; its propagation delay is specified from address or enable inputs to outputs. The 74HC165D,653 is a clocked shift register with maximum shift frequency and clock-to-output propagation delay specifications. The timing parameters are therefore not directly comparable.
Which device is more suitable for expanding the input pins of a microcontroller?
The 74HC165D,653 is more suitable for input expansion because it converts eight parallel inputs into a serial data stream, allowing a microcontroller to read many inputs using only a few pins. The 74HC139D is intended for output decoding or demultiplexing and does not provide serial input expansion.