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 74HC154D,653 are not functionally interchangeable. The 74HC139D is a dual 2-to-4 line decoder/demultiplexer with two independent 2-bit address inputs and four active-low outputs per section, while the 74HC154D,653 is a single 4-to-16 line decoder/demultiplexer with a 4-bit address input and sixteen active-low outputs. The fundamental differences in channel count, address width, output count, and package pinout make direct substitution impossible without redesigning the surrounding circuitry.
Different channel count
Different address width
Different output count
Different footprint
Parts at a glance
Part B
74HC154D,653
NXP Hoa Kỳ Inc.
- Lifecycle
- Active
- Stock
- 4133 PCS
- Package
- SOIC-24
- Series
- Logic - Signal Switches, Multiplexers, Decoders
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 | 74HC154D,653 | Why it matters |
|---|---|---|---|
| Function | Dual 2-to-4 line decoder/demultiplexer | Single 4-to-16 line decoder/demultiplexer | Defines the core logic function; the two devices decode different numbers of input lines and cannot directly replace one another without redesign. |
| Number of Decoders | 2 | 1 | Affects how many independent decode channels are available in a single package. |
| Number of Outputs | 8 (two groups of 4) | 16 | Determines how many selectable output lines the device can drive, directly impacting addressable peripherals or channels. |
| Input Lines per Decoder | 2 (A0, A1) per decoder | 4 (A0–A3) | Sets the binary address width and thus the number of unique output states. |
| Enable Inputs | 2 active-LOW enable inputs (one per decoder) | 2 active-LOW enable inputs (E1, E2) | Enable pins control when outputs are active or forced HIGH, critical for cascading and bus sharing. |
| Output Type | Active-LOW outputs | Active-LOW outputs | Output polarity must match the driven load or downstream logic to avoid inverted control signals. |
| Package | SO16 (SOIC-16) | SO24 (SOIC-24) | Different pin counts and footprints prevent drop-in board replacement without layout changes. |
| Pin Count | 16 | 24 | Pin count determines package size, routing complexity, and PCB footprint compatibility. |
| 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. |
| Propagation Delay (typical at 5 V) | Approximately 14 ns | Approximately 15 ns | Timing affects maximum operating frequency and signal integrity in high-speed decoding paths. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC139D | 74HC154D,653 |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | 74HC | 74HC |
| Part Status | Obsolete | Active |
| Type | Decoder/Demultiplexer | Decoder/Demultiplexer |
| Circuit | 1 x 2:4 | 1 x 4:16 |
| Independent Circuits | 2 | 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 74HC139D and the 74HC154D,653?
The 74HC139D is a dual 2-to-4 line decoder/demultiplexer, meaning it contains two independent decoders in one package. The 74HC154D,653 is a single 4-to-16 line decoder/demultiplexer. The 74HC139D provides 4 active-low outputs per decoder (8 total), while the 74HC154D,653 provides 16 active-low outputs.
Are the 74HC139D and 74HC154D,653 pin-compatible?
No. The 74HC139D is typically supplied in a 16-pin package (SO16), while the 74HC154D,653 is supplied in a 24-pin package (SO24). They have different pin counts, pinouts, and PCB land patterns, so they are not drop-in replacements for each other.
Can the 74HC139D be used to replace the 74HC154D,653 in an existing design?
Not directly. The 74HC139D has fewer inputs and outputs and a different logic function. Replacing a 4-to-16 decoder with a dual 2-to-4 decoder would require external logic, additional board space, and a redesign of the address decoding circuitry. Functional equivalence is not maintained.
What are the supply voltage and logic family specifications for both devices?
Both the 74HC139D and 74HC154D,653 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. Exact limits should be confirmed on the respective manufacturer datasheets.
How do the propagation delays of the 74HC139D and 74HC154D,653 compare?
Both devices are 74HC-family parts and have similar propagation delay characteristics, typically in the low nanosecond range at 5 V. However, the 74HC154D,653 may exhibit slightly different timing due to its larger decoder tree. Designers should verify the specific tPD values from the official datasheets for the exact operating conditions.
What are the typical applications for the 74HC139D versus the 74HC154D,653?
The 74HC139D is commonly used for small-scale address decoding, memory chip selection, and demultiplexing in systems requiring two independent 2-to-4 decoders. The 74HC154D,653 is used for larger address decoding tasks, such as selecting one of 16 memory banks or peripherals, and for 4-to-16 demultiplexing applications.
Do both devices have active-low outputs?
Yes. The 74HC139D has four active-low outputs per decoder (Y0 to Y3), and the 74HC154D,653 has sixteen active-low outputs (Y0 to Y15). In both cases, the selected output goes LOW while the unselected outputs remain HIGH.
What are the package and mounting types for the 74HC139D and 74HC154D,653?
The 74HC139D is typically offered in a 16-pin SOIC package (SO16). The 74HC154D,653 is typically offered in a 24-pin SOIC package (SO24). Both are surface-mount devices. Package suffixes and exact mechanical dimensions should be verified from the manufacturer datasheet.