Part A
74HC02D
Toshiba Semiconductor and Storage
- Lifecycle
- Active
- Stock
- 1347 PCS
- Package
- SOIC-14
- Series
- Logic - Gates and Inverters
Replacement verdict
Not a drop-in replacement
The 74HC08D and 74HC02D are not functionally interchangeable despite sharing the same 74HC CMOS logic family, SOIC-14 package, and supply voltage range. The 74HC08D provides four 2-input AND gates, while the 74HC02D provides four 2-input NOR gates, resulting in fundamentally different logic functions and truth tables. Direct substitution is not possible without redesigning the surrounding logic circuit.
Different logic function
Different output polarity
Different truth table
Circuit redesign required
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC08D | 74HC02D | Why it matters |
|---|---|---|---|
| Logic Function | Quad 2-input AND gate | Quad 2-input NOR gate | Defines the Boolean operation performed; AND and NOR are not functionally interchangeable without additional logic. |
| Output Logic Level (Active State) | HIGH when all inputs are HIGH | LOW when any input is HIGH | Determines the output polarity for given inputs, directly affecting circuit behavior and downstream logic. |
| Supply Voltage Range | 2.0 V to 6.0 V | 2.0 V to 6.0 V | Both parts operate over the standard HC-family supply range, allowing use in 3.3 V and 5 V systems. |
| Number of Gates | 4 | 4 | Matching gate count supports similar board-level integration and package pin utilization. |
| Number of Inputs per Gate | 2 | 2 | Identical input count simplifies pinout compatibility and logic design translation. |
| Package | SOIC-14 | SOIC-14 | Same package footprint enables direct PCB drop-in replacement without layout changes. |
| Pin Count | 14 | 14 | Equal pin count supports mechanical and footprint compatibility. |
| Propagation Delay (typical at 5 V) | ~9 ns | ~9 ns | Similar timing performance ensures comparable speed in signal paths. |
| Output Drive Current | ±4 mA (at 5 V) | ±4 mA (at 5 V) | Matching drive strength supports similar fan-out and load-driving capability. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Identical temperature ratings allow use in the same industrial and automotive environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC02D | 74HC08D |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | NOR Gate | AND Gate |
| Number of Circuits | 4 | 4 |
| Number of Inputs | 2 | 2 |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Current - Quiescent (Max) | 1 µA | 1 µA |
| Current - Output High Low | 5.2mA, 5.2mA | 5.2mA, 5.2mA |
| Logic Level - Low | 0.5V ~ 1.8V | 0.5V ~ 1.8V |
| Logic Level - High | 1.5V ~ 4.2V | 1.5V ~ 4.2V |
| Max Propagation Delay @ V Max CL | 16ns @ 6V, 50pF | 13ns @ 6V, 50pF |
| 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 74HC08D and 74HC02D?
The 74HC08D contains four independent 2-input AND gates, while the 74HC02D contains four independent 2-input NOR gates. Both are quad 2-input logic gates in the 74HC high-speed CMOS family, but they implement different Boolean functions and therefore are not functionally interchangeable.
Are the 74HC08D and 74HC02D pin-compatible?
Yes. Both devices are typically offered in the SO14 package (the "D" suffix in NXP and similar naming conventions denotes SO14) and use the same standard 14-pin quad 2-input gate pinout: pins 1, 2, 4, 5, 9, 10, 12, and 13 are inputs; pins 3, 6, 8, and 11 are outputs; pin 7 is GND; and pin 14 is VCC. Because the pinout is identical, a board designed for one device can physically accept the other, but the logic function performed will differ.
Can the 74HC08D be used as a direct drop-in replacement for the 74HC02D in an existing design?
No, not as a functional replacement. Although the package and pinout are the same, the 74HC08D performs AND logic while the 74HC02D performs NOR logic. Substituting one for the other will change the circuit's logic behavior and is only valid if the design is specifically modified or if the surrounding circuitry accounts for the different truth table.
What are the typical supply voltage and logic level specifications for both devices?
Both the 74HC08D and 74HC02D operate from a supply voltage range of 2.0 V to 6.0 V, with 5.0 V being the most common operating condition. They are CMOS devices with standard 74HC input thresholds and are compatible with TTL output levels when operated at 5 V. Exact V_IH, V_IL, V_OH, and V_OL limits should be confirmed from the specific manufacturer datasheet.
Do the 74HC08D and 74HC02D have the same propagation delay and drive characteristics?
Both are members of the same 74HC logic family and are specified with similar propagation delays and output drive capabilities, typically on the order of a few nanoseconds at 5 V and capable of driving standard CMOS and TTL loads. However, exact timing and drive parameters can vary by manufacturer, so the datasheet for the specific part number should be consulted for guaranteed limits.
Are the 74HC08D and 74HC02D available in the same package options?
Both devices are commonly available in SO14 (D suffix), TSSOP14, and DIP14 packages from various manufacturers. The "D" suffix specifically indicates the SO14 package in many manufacturer naming conventions, so the 74HC08D and 74HC02D are both SO14 devices when that suffix is used.
What are typical applications for the 74HC08D versus the 74HC02D?
The 74HC08D (AND gates) is commonly used for enable/disable gating, signal qualification, and combining control signals where all conditions must be true. The 74HC02D (NOR gates) is commonly used for active-low logic, set/reset latch implementations, and applications requiring inverted OR logic. The choice depends on the required Boolean function in the target circuit.
Do both devices have the same input and output current ratings?
As members of the same 74HC family, both the 74HC08D and 74HC02D typically share similar DC input and output current specifications, including standard CMOS input leakage and output drive currents. However, because they are different logic functions, the output state conditions under which those currents are specified may differ. Always verify against the manufacturer datasheet for the exact part.