Part A
74HC138D
Toshiba Semiconductor và lưu trữ
- Lifecycle
- Active
- Stock
- 2131 PCS
- Package
- SOIC-16
- Series
- Logic - Signal Switches, Multiplexers, Decoders
Replacement verdict
Not a drop-in replacement
The 74HC138D and 74HC132D,652 are functionally distinct logic ICs and cannot serve as substitutes for one another. The 74HC138D is a 3-to-8 line decoder/demultiplexer, while the 74HC132D,652 is a quad 2-input NAND Schmitt trigger. Their core logic functions, input/output configurations, and pin assignments differ fundamentally, making direct replacement infeasible without significant circuit redesign.
Different logic function
Different input configuration
Different output type
Different pin assignment
Parts at a glance
Part B
74HC132D,652
NXP bán dẫn
- Lifecycle
- Active
- Stock
- 4717 PCS
- Series
- Logic - Gates and Inverters
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC138D | 74HC132D,652 | Why it matters |
|---|---|---|---|
| Logic Function | 3-to-8 line decoder/demultiplexer | Quad 2-input NAND Schmitt trigger | The core logic function determines whether the devices are functionally interchangeable in a circuit; these two parts perform completely different operations. |
| Number of Gates/Channels | 1 decoder (8 outputs) | 4 NAND gates | Channel count affects how many independent signal paths can be handled per package. |
| Input Type | Standard CMOS | Schmitt trigger | Schmitt trigger inputs provide hysteresis for noise immunity and slow-edge signal conditioning, which standard CMOS inputs do not. |
| Output Type | Active-low outputs (inverting) | Standard push-pull | Output polarity and drive style must match the downstream circuit requirements. |
| Number of Pins | 16 | 14 | Pin count affects PCB footprint and package compatibility. |
| Package | SO-16 | SO-14 | Different package sizes are not drop-in compatible on the same PCB land pattern. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both parts operate over the same HC-family supply range, allowing use in similar logic-level systems. |
| Logic Family | 74HC | 74HC | Same logic family ensures compatible voltage thresholds and interfacing characteristics. |
| Propagation Delay | Approx. 15 ns at 4.5 V | Approx. 19 ns at 4.5 V | Propagation delay affects timing margins in high-speed digital circuits. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Both support industrial temperature ranges, but verification against the specific manufacturer datasheet is required for exact limits. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC138D | 74HC132D,652 |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Part Status | Active | Active |
| Series | 74HC | - |
| Type | Decoder/Demultiplexer | - |
| Circuit | 1 x 3:8 | - |
| Independent Circuits | 1 | - |
| Current - Output High Low | 5.2mA, 5.2mA | - |
| Voltage Supply Source | Single Supply | - |
| Voltage - Supply | 2V ~ 6V | - |
| Operating Temperature | -40°C ~ 125°C | - |
| Mounting Type | Surface Mount | - |
Frequently asked questions
What are the primary functional differences between the 74HC138D and the 74HC132D,652?
The 74HC138D is a 3-to-8 line decoder/demultiplexer that accepts a 3-bit binary address and activates one of eight mutually exclusive outputs. The 74HC132D,652 contains four independent 2-input NAND gates with Schmitt-trigger inputs, providing hysteresis for slow or noisy input signals. They are functionally unrelated logic devices.
Are the 74HC138D and 74HC132D,652 pin-compatible?
No. The 74HC138D is typically supplied in a 16-pin SOIC package, while the 74HC132D,652 is typically supplied in a 14-pin SOIC package. They have different pin counts, pin assignments, and functions, so they are not pin-compatible or interchangeable.
Can the 74HC138D and 74HC132D,652 operate from the same supply voltage range?
Yes. Both devices are members of the 74HC logic family and are specified for a nominal supply voltage range of 2.0 V to 6.0 V, with 5 V being the most common operating voltage. However, this shared supply range does not make them functionally equivalent.
Does the 74HC132D,652 have Schmitt-trigger inputs on all gates?
Yes. The 74HC132D,652 is defined as a quad 2-input NAND Schmitt trigger. Each of the four NAND gates has Schmitt-trigger inputs with defined positive and negative threshold voltages, providing input hysteresis for noise immunity and slow edge transitions.
What is the logic function of the 74HC138D?
The 74HC138D is a 3-to-8 decoder/demultiplexer. It uses three binary select inputs (A0, A1, A2) and three enable inputs (two active-low and one active-high) to select one of eight active-low outputs. When enabled, exactly one output is LOW while the others remain HIGH.
Can the 74HC138D be used as a demultiplexer?
Yes. The 74HC138D can function as a 1-to-8 demultiplexer when one of its enable inputs is used as the data input and the three select inputs are used as address lines. The selected output follows the data input, while the unselected outputs remain inactive.
Are the 74HC138D and 74HC132D,652 available in the same package type?
Both devices are commonly available in SOIC packages, but not the same SOIC package. The 74HC138D is typically a 16-pin SOIC, while the 74HC132D,652 is typically a 14-pin SOIC. Package type similarity does not imply package compatibility.
Which device is better for debouncing a mechanical switch?
The 74HC132D,652 is the appropriate choice for debouncing or conditioning slow and noisy signals because its Schmitt-trigger inputs provide hysteresis. The 74HC138D does not have Schmitt-trigger inputs and is intended for address decoding or demultiplexing, not signal conditioning.
Do both devices have the same output drive capability?
Both are 74HC-family CMOS devices and generally provide similar standard output drive characteristics, typically specified as ±4 mA at 5 V for balanced CMOS outputs. However, the 74HC138D outputs are active-low decoder outputs, while the 74HC132D,652 outputs are NAND gate outputs, so the output logic polarity and function differ.