Part A
74HC139D
Toshiba Halbleiter und Speicher
- Lifecycle
- Active
- Stock
- 4290 Stückzahl
- Package
- SOIC-16
- Series
- Logic.Signal Schalter, Multiplexer, Decoder
Replacement verdict
Not a drop-in replacement
The 74HC139D and 74HC154D,652 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,652 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 prevent direct substitution without significant circuit redesign.
Different channel count
Different address width
Different output count
Different footprint
Parts at a glance
Part B
74HC154D,652
NXP USA Inc.
- Lifecycle
- Active
- Stock
- 2528 Stückzahl
- Package
- SOIC-24
- Series
- Logic.Signal Schalter, Multiplexer, Decoder
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,652 | 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 each other in a circuit. |
| Number of Decoders | 2 | 1 | Determines how many independent decoding blocks are available on a single chip. |
| Number of Outputs | 8 (two groups of 4) | 16 | Affects how many peripheral devices or address lines can be selected. |
| Address/Select Inputs | 2 per decoder (A0, A1) | 4 (A0–A3) | Determines the number of binary input lines needed to select an output. |
| Enable Inputs | 1 active-LOW enable per decoder (2 total) | 2 active-LOW enables (E1, E2) | Enable pins control when the decoder is active and are essential for cascading or gating logic. |
| Output Type | Active-LOW outputs | Active-LOW outputs | Output polarity must match the driven load or subsequent logic stage. |
| Package | SOIC-16 (D suffix) | SOIC-24 (D suffix) | Different pin counts and footprints prevent direct PCB drop-in replacement. |
| Pin Count | 16 | 24 | Pin count affects board layout, routing, and package compatibility. |
| Supply Voltage Range | 2.0 V to 6.0 V | 2.0 V to 6.0 V | Both operate over the standard HC-family voltage range, so supply compatibility is not a differentiator. |
| Propagation Delay (typical) | ~14 ns at 4.5 V | ~18 ns at 4.5 V | Timing differences can affect setup/hold margins in high-speed address decoding. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC139D | 74HC154D,652 |
|---|---|---|
| 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,652?
The 74HC139D is a dual 2-to-4 line decoder/demultiplexer, meaning it contains two independent decoders in one package. The 74HC154D,652 is a single 4-to-16 line decoder/demultiplexer. The 74HC139D provides 4 outputs per decoder (8 total), while the 74HC154D,652 provides 16 outputs.
Are the 74HC139D and 74HC154D,652 pin-compatible?
No. The 74HC139D is typically supplied in a 16-pin package (SO16 or DIP16), while the 74HC154D,652 is supplied in a 24-pin package (SO24 or DIP24). They have different pin counts and pinouts, so they are not drop-in replacements for each other.
Can the 74HC139D be used to replace the 74HC154D,652 in an existing design?
Not directly. The 74HC154D,652 decodes 4 input lines to 16 mutually exclusive outputs, whereas the 74HC139D decodes 2 input lines to 4 outputs per section. Replacing one with the other would require additional logic, wiring changes, and a different PCB footprint.
What are the typical propagation delays for these devices?
Both devices are 74HC CMOS logic. At a 4.5 V supply, the 74HC139D typically has a propagation delay from address inputs to outputs of approximately 14 ns to 20 ns depending on the manufacturer. The 74HC154D,652 typically has a propagation delay of approximately 18 ns to 25 ns at 4.5 V. Exact values vary by manufacturer and should be verified on the specific datasheet.
What is the operating voltage range for the 74HC139D and 74HC154D,652?
Both are 74HC series high-speed CMOS devices and operate over a supply voltage range of 2.0 V to 6.0 V. They are not 5 V-only devices, though they are commonly used in 5 V and 3.3 V systems.
How many address inputs does each device have?
The 74HC139D has two sets of 2 address inputs (A0 and A1 per decoder), plus an active-low enable input per decoder. The 74HC154D,652 has 4 address inputs (A0 through A3) and two active-low enable inputs (E1 and E2).
Are the outputs active-high or active-low?
Both the 74HC139D and the 74HC154D,652 have active-low outputs. When a given output is selected, it goes LOW while all other outputs remain HIGH.
Which device is better for expanding to 16 outputs?
The 74HC154D,652 is the appropriate choice for directly decoding 4 binary inputs to 16 active-low outputs in a single package. Using 74HC139D devices would require two ICs plus additional logic to combine enables and avoid output conflicts, increasing component count and board space.