Part A
74HC374D
恩智浦美國股份有限公司。
- Lifecycle
- Active
- Stock
- 4193 件
- Package
- SOIC-20
- Series
- 邏輯-觸發器
Replacement verdict
Not a drop-in replacement
The 74HC393D and 74HC374D are not functionally interchangeable despite sharing the same 74HC logic family and SOIC-14 package. The 74HC393D is a dual 4-bit binary ripple counter with asynchronous clear, while the 74HC374D is an octal D-type flip-flop with 3-state outputs and edge-triggered clocking. Their internal architectures, pin functions, and logic operations are fundamentally different, making direct substitution impossible without complete circuit redesign.
Different logic function
Different output type
Different pinout
Different clocking method
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC393D | 74HC374D | Why it matters |
|---|---|---|---|
| Logic Function | Dual 4-bit binary ripple counter | Octal D-type flip-flop with 3-state outputs | Defines the core function; these devices are not functionally interchangeable as they perform completely different logic operations. |
| Number of Flip-Flops / Counters | 2 independent 4-bit counters (8 flip-flops total) | 8 D-type flip-flops | Determines how many bits or channels the device can process simultaneously. |
| Output Type | Buffered push-pull (totem-pole) | 3-state (tri-state) non-inverting | 3-state outputs allow bus sharing; push-pull outputs cannot be tied together, affecting system architecture. |
| Clock Input | Ripple clock (asynchronous internal stages) | Single common edge-triggered clock | Ripple counters have cumulative propagation delay; edge-triggered flip-flops update all outputs simultaneously. |
| Control Inputs | Master reset (active LOW) per counter | Output enable (OE, active LOW) and clock | Different control schemes dictate how the device is initialized and when outputs are driven. |
| Supply Voltage Range | 2.0 V to 6.0 V | 2.0 V to 6.0 V | Both are HC-family CMOS devices, so they share the same wide operating voltage range and logic-level compatibility. |
| Package | SO14 (14-pin SOIC) | SO20 (20-pin SOIC) | Different pin counts and footprints mean they are not drop-in replacements on a PCB. |
| Logic Family | 74HC (High-speed CMOS) | 74HC (High-speed CMOS) | Same family ensures compatible input thresholds, noise margins, and drive characteristics. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Both support industrial temperature ranges, suitable for the same environmental conditions. |
| Propagation Delay (typical at 5 V) | ~14 ns per stage (ripple) | ~15 ns (clock to output) | Timing affects maximum operating frequency and setup/hold requirements in synchronous designs. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC374D | 74HC393D |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Function | Standard | - |
| Type | D-Type | - |
| Output Type | Tri-State, Non-Inverted | - |
| Number of Elements | 1 | 2 |
| Number of Bits per Element | 8 | 4 |
| Clock Frequency | 90 MHz | - |
| Max Propagation Delay @ V Max CL | 32ns @ 6V, 150pF | - |
| Trigger Type | Positive Edge | Negative Edge |
| Current - Output High Low | 7.8mA, 7.8mA | - |
| Voltage - Supply | 2V ~ 6V | 2 V ~ 6 V |
| Current - Quiescent (Iq) | 4 µA | - |
| Input Capacitance | 3 pF | - |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
| Logic Type | - | Binary Counter |
| Direction | - | Up |
| Count Rate | - | 32 MHz |
Frequently asked questions
What are the primary functional differences between the 74HC393D and the 74HC374D?
The 74HC393D is a dual 4-bit binary ripple counter, while the 74HC374D is an octal D-type flip-flop with 3-state outputs. The 74HC393D counts pulses and provides binary count outputs, whereas the 74HC374D stores and transfers 8 bits of data synchronously on a clock edge.
Are the 74HC393D and 74HC374D pin-compatible?
No. The 74HC393D is typically supplied in a 14-pin SOIC package, and the 74HC374D is typically supplied in a 20-pin SOIC package. They have different pin counts and pin functions, so they are not pin-compatible.
Can the 74HC393D and 74HC374D be used together in the same design?
Yes. They perform different logic functions and can be used together. For example, the 74HC393D can generate binary counts or timing signals, and the 74HC374D can latch and buffer data or count values for a bus.
What is the difference in output type between the 74HC393D and the 74HC374D?
The 74HC393D provides standard push-pull binary counter outputs. The 74HC374D provides 3-state outputs, allowing its outputs to be placed in a high-impedance state for bus sharing.
Do both the 74HC393D and 74HC374D operate on the same supply voltage range?
Yes. Both are 74HC-series CMOS devices and typically operate over a supply voltage range of 2.0 V to 6.0 V, with 5.0 V being a common nominal operating voltage.
Which device is better for frequency division, the 74HC393D or the 74HC374D?
The 74HC393D is intended for counting and frequency division because it contains dual 4-bit binary ripple counters. The 74HC374D is not a counter; it is an octal edge-triggered D-type flip-flop used for data storage and transfer.
Can the 74HC374D replace the 74HC393D in a counting application?
No. The 74HC374D does not contain internal counter stages and cannot perform binary counting or frequency division by itself. Replacing a 74HC393D with a 74HC374D would require additional logic and a redesign.
What are the typical clock-related characteristics of the 74HC393D and 74HC374D?
The 74HC393D is a ripple counter in which each stage is clocked by the preceding stage, so propagation delay accumulates. The 74HC374D is a synchronous octal flip-flop in which all eight outputs update simultaneously on a single clock edge.