Part A
74HC245D
Toshiba Halbleiter und Speicher
- Lifecycle
- Active
- Stock
- 4218 Stückzahl
- Package
- SOIC-14
- Series
- Logic c Puffer, Treiber, Empfänger, Transceiver
Replacement verdict
Not a drop-in replacement
The 74HC245D and 74HC251D-Q100J are functionally unrelated devices: the former is an octal bidirectional bus transceiver with 3-state outputs, while the latter is a single 8-channel multiplexer with 3-state complementary outputs. They differ in logic function, channel configuration, output behavior, and package/pinout, so neither can directly substitute for the other in an existing design without significant circuit redesign.
Different logic function
Different channel configuration
Different output type
Different package and pinout
Parts at a glance
Part B
74HC251D-Q100J
Nexperia USA Inc.
- Lifecycle
- Active
- Stock
- 6040 Stückzahl
- Package
- SOIC-16
- 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 | 74HC245D | 74HC251D-Q100J | Why it matters |
|---|---|---|---|
| Function | Octal bus transceiver with 3-state outputs | 8-input multiplexer with 3-state outputs | These devices perform fundamentally different logic functions, so they are not functionally interchangeable in a circuit. |
| Logic Type | Bidirectional transceiver | Multiplexer | The logic type determines the signal routing behavior and cannot be substituted without redesigning the surrounding circuit. |
| Number of Channels | 8 | 1 (8:1 multiplexer) | Channel count affects how many signals can be handled simultaneously and the required board layout. |
| Direction Control | Direction pin (DIR) selects A-to-B or B-to-A | Not applicable; select inputs choose one of eight inputs | Direction control is essential for bus transceiver operation but has no equivalent in a multiplexer. |
| Output Type | 3-state | 3-state | Both offer 3-state outputs, but the control logic and data path differ significantly. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Compatible supply voltage ranges allow both to operate in similar logic-level systems. |
| Package | SOIC-20 | SOIC-16 | Different package sizes and pin counts prevent direct drop-in replacement on the same PCB footprint. |
| Pin Count | 20 | 16 | Pin count mismatch means the devices cannot share the same socket or land pattern. |
| Qualification | Standard commercial | AEC-Q100 qualified | AEC-Q100 qualification indicates the multiplexer is suitable for automotive applications, while the transceiver is not. |
| Propagation Delay | Typically 8 ns at 5 V | Typically 11 ns at 5 V | Different propagation delays affect timing margins in high-speed digital designs. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC245D | 74HC251D-Q100J |
|---|---|---|
| Supplier | - | Nexperia USA Inc. |
| Series | 74HC | Automotive, AEC-Q100, 74HC |
| Part Status | Active | Active |
| Type | - | Multiplexer |
| Circuit | - | 1 x 8:1 |
| Independent Circuits | - | 1 |
| Current - Output High Low | 7.8mA, 7.8mA | 5.2mA, 5.2mA |
| Voltage Supply Source | - | Single Supply |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Logic Type | Transceiver, Non-Inverting | - |
| Number of Elements | 1 | - |
| Number of Bits per Element | 8 | - |
| Output Type | 3-State | - |