Part A
74HC138D
Toshiba Semiconductor and Storage
- Lifecycle
- Active
- Stock
- 2131 PCS
- Package
- SOIC-16
- Series
- Logic - Signal Switches, Multiplexers, Decoders
Replacement verdict
Not a drop-in replacement
The 74HC153D and 74HC138D are not functionally interchangeable despite sharing the same 74HC CMOS logic family and 16-pin SOIC package. The 74HC153D is a dual 4-to-1 data selector/multiplexer with non-inverting outputs, while the 74HC138D is a 3-to-8 line decoder/demultiplexer with active-low outputs. Their internal logic functions, pin assignments, and output configurations are fundamentally different, making direct substitution impossible without circuit redesign.
Different logic function
Different output polarity
Different pin assignment
Different input configuration
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC153D | 74HC138D | Why it matters |
|---|---|---|---|
| Function | Dual 4-input multiplexer | 3-to-8 line decoder/demultiplexer | These devices perform fundamentally different logic functions, so they are not functionally interchangeable in a circuit. |
| Number of Select/Address Inputs | 2 (shared per multiplexer) | 3 (A, B, C) | The number of select lines determines how many data or output channels can be addressed. |
| Number of Data Inputs | 8 (two groups of 4) | 1 (demultiplexer data input via enable pins) | Input count defines how many signal sources the device can route or process. |
| Number of Outputs | 2 (one per multiplexer) | 8 (active-low) | Output count and polarity affect how the device interfaces with downstream logic. |
| Output Type | Push-pull (totem-pole) | Active-low push-pull | Output polarity and drive style determine compatibility with connected loads and logic levels. |
| Enable/Strobe Inputs | 2 active-low enable inputs (one per multiplexer) | 3 enable inputs (two active-low, one active-high) | Enable inputs control when the device is active and are essential for cascading and bus sharing. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Matching supply ranges ensures both devices can operate in the same logic-level environment. |
| Logic Family | HC (High-speed CMOS) | HC (High-speed CMOS) | Same logic family means compatible input thresholds, noise margins, and drive characteristics. |
| Package | SOIC-16 (D suffix) | SOIC-16 (D suffix) | Identical package and pin count allow the same PCB footprint, though pin functions differ. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Matching temperature ranges ensure both parts suit the same application environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC138D | 74HC153D |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Type | Decoder/Demultiplexer | Multiplexer |
| Circuit | 1 x 3:8 | 2 x 4:1 |
| Independent Circuits | 1 | 2 |
| 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 ~ 125°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the primary functional differences between the 74HC153D and the 74HC138D?
The 74HC153D is a dual 4-input multiplexer that selects one of four data inputs for each of its two independent outputs based on two select lines. The 74HC138D is a 3-to-8 line decoder/demultiplexer that activates one of eight mutually exclusive outputs based on a 3-bit binary address. They serve fundamentally different logic functions and are not functionally interchangeable.
Are the 74HC153D and 74HC138D pin-compatible in the SOIC-16 package?
No. Although both devices are commonly offered in a 16-pin SOIC package, their pinouts differ. The 74HC153D assigns pins to two separate 4-input multiplexer sections with individual strobe inputs, while the 74HC138D assigns pins to three address inputs, three enable inputs, and eight decoded outputs. Direct PCB substitution without layout changes is not possible.
Can the 74HC153D be used to implement the same logic as the 74HC138D?
Not directly. The 74HC138D provides eight mutually exclusive active-LOW outputs from a 3-bit address plus enable inputs. The 74HC153D provides two multiplexed outputs from two sets of four data inputs. Implementing a 3-to-8 decoder with a 74HC153D would require additional external logic gates and is not a pin-for-pin or function-for-function replacement.
What are the supply voltage and logic family specifications for both devices?
Both the 74HC153D and 74HC138D 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 against the specific manufacturer datasheet, as parameters such as propagation delay and output drive may vary slightly between vendors.
Which device is better suited for expanding I/O lines in a microcontroller system?
The 74HC138D is generally used for address decoding or output expansion, activating one of eight outputs from a 3-bit address. The 74HC153D is used for data selection, routing one of four inputs to an output. The choice depends on whether the application requires selection (multiplexing) or decoding (address-to-output activation).
Do both devices have the same operating temperature range?
Both the 74HC153D and 74HC138D are typically specified for the industrial temperature range of -40 °C to +125 °C when purchased in standard SOIC-16 packaging from major manufacturers. However, the exact temperature grade should always be verified on the specific manufacturer datasheet, as some variants may differ.
Are the 74HC153D and 74HC138D interchangeable in existing designs?
No. Because they perform different logic functions and have different pinouts, they cannot be interchanged without redesigning the circuit. The 74HC153D is a multiplexer, while the 74HC138D is a decoder/demultiplexer. Substitution requires verifying all functional, pinout, and timing requirements against the target design.