Part A
74HC374D
NXP USA Inc.
- Lifecycle
- Active
- Stock
- 4193 Stückzahl
- Package
- SOIC-20
- Series
- Logik für Flip Flops
Replacement verdict
Compatible functional replacement candidate
The 74HC374D and 74HC377D,652 are both octal D-type flip-flops in the 74HC logic family, sharing identical supply voltage ranges, package footprints, and pin counts. However, they differ in clock enable architecture and output control, so the 74HC377D,652 can serve as a functional substitute for the 74HC374D only when the system design accommodates the clock enable versus output enable distinction and the inverted output polarity of the 74HC377D,652.
Logic Function
High match
Package Type
High match
Control Input Architecture
Validation required
Output Polarity
Not compatible
Parts at a glance
Part B
74HC377D,652
NXP USA Inc.
- Lifecycle
- Active
- Stock
- 2545 Stückzahl
- Series
- Logik für Flip Flops
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC374D | 74HC377D,652 | Why it matters |
|---|---|---|---|
| Logic Type | D-Type Flip-Flop (Octal, 3-State) | D-Type Flip-Flop (Octal, 3-State) | Both are octal D-type flip-flops, but the 374 and 377 differ in clock enable architecture, affecting how data is latched. |
| Clock Enable | No clock enable (clocked on every rising edge) | Has clock enable (CP) input to gate clocking | The 377 allows holding the register state by disabling the clock, while the 374 latches on every clock edge, affecting timing control in a design. |
| Output Enable | Yes (OE, active LOW) | Yes (OE, active LOW) | Both provide 3-state outputs for bus interfacing, but the control pin arrangement differs between the two devices. |
| Number of Flip-Flops | 8 | 8 | Both are octal devices, so bus width compatibility is identical. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both operate over the standard HC family voltage range, allowing use in 3.3 V and 5 V systems. |
| Propagation Delay (typical at 5 V) | ~15 ns | ~15 ns | Similar propagation delay means comparable speed performance in synchronous designs. |
| Package | SOIC-20 (D suffix) | SOIC-20 (D suffix) | Same package footprint allows direct PCB drop-in replacement without layout changes. |
| Pin Count | 20 | 20 | Identical pin count, but pin functions differ (clock enable vs. no clock enable), so pin-to-pin compatibility is not guaranteed. |
| Input Type | Standard CMOS | Standard CMOS | Both have CMOS-compatible inputs, ensuring similar logic level thresholds and noise immunity. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Both support industrial temperature ranges, suitable for harsh environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC374D | 74HC377D,652 |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Function | Standard | Standard |
| Type | D-Type | D-Type |
| Output Type | Tri-State, Non-Inverted | Non-Inverted |
| Number of Elements | 1 | 1 |
| Number of Bits per Element | 8 | 8 |
| Clock Frequency | 90 MHz | 83 MHz |
| Max Propagation Delay @ V Max CL | 32ns @ 6V, 150pF | 27ns @ 6V, 50pF |
| Trigger Type | Positive Edge | Positive Edge |
| Current - Output High Low | 7.8mA, 7.8mA | 5.2mA, 5.2mA |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Current - Quiescent (Iq) | 4 µA | 8 µA |
| Input Capacitance | 3 pF | 3.5 pF |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What is the main functional difference between the 74HC374D and the 74HC377D,652?
The 74HC374D is an octal D-type flip-flop with 3-state outputs that latches data on the rising edge of the clock (CP). The 74HC377D,652 is an octal D-type flip-flop with 3-state outputs that latches data on the rising edge of the clock but includes a clock enable (CE) input, allowing the clock to be gated internally. Both are 8-bit registers, but the 74HC377D,652 provides an additional clock enable function.
Are the 74HC374D and 74HC377D,652 pin-compatible?
No, they are not pin-compatible. The 74HC374D has a pinout with output enable (OE) on pin 1 and clock (CP) on pin 11. The 74HC377D,652 has clock enable (CE) on pin 1 and clock (CP) on pin 11, with output enable (OE) on pin 1 in some variants, but the standard 74HC377 pinout differs. Designers must consult the specific manufacturer datasheet for exact pin assignments before substitution.
Can the 74HC374D be replaced directly with the 74HC377D,652 in an existing design?
Not directly. The 74HC377D,652 includes a clock enable (CE) input that the 74HC374D lacks. If the CE pin is not properly driven (e.g., tied low for always-enabled operation), the 74HC377D,652 may not function as a drop-in replacement. The PCB layout and pin functions differ, so a direct replacement requires design validation.
What is the maximum operating frequency of the 74HC374D and 74HC377D,652?
Both devices are 74HC series high-speed CMOS logic. Typical maximum operating frequency for 74HC374 and 74HC377 at 5 V is around 50 MHz to 70 MHz, depending on the manufacturer and load conditions. Exact values must be verified from the specific manufacturer datasheet, as parameters vary with supply voltage and temperature.
What are the supply voltage ranges for the 74HC374D and 74HC377D,652?
Both the 74HC374D and 74HC377D,652 operate over a supply voltage range of 2 V to 6 V, typical for 74HC series CMOS logic. The recommended operating voltage is often 4.5 V to 5.5 V for 5 V systems, but the full range supports 2 V to 6 V per JEDEC standards. Always confirm with the manufacturer datasheet.
Do both devices have 3-state outputs?
Yes, both the 74HC374D and 74HC377D,652 feature 3-state outputs, allowing them to be connected to a shared bus. The output enable (OE) control pin, when active, places the outputs in a high-impedance state. The OE pin function is present on both devices, though pin numbering may differ.
What is the difference in propagation delay between the 74HC374D and 74HC377D,652?
Propagation delay for both devices is similar, typically around 13 ns to 20 ns at 5 V supply and 25°C, depending on the manufacturer. The 74HC377D,652 may have a slightly different delay due to the additional clock enable circuitry, but both are in the same performance class. Verify exact timing from the specific datasheet.
Which device is better for bus-oriented applications?
Both are suitable for bus-oriented applications due to their 3-state outputs. The 74HC374D is simpler with a single clock input, while the 74HC377D,652 offers a clock enable that can simplify gating logic in systems where multiple registers share a clock. The choice depends on whether clock gating is required in the design.