Part A
74HC574D
Toshiba Halbleiter und Speicher
- Lifecycle
- Active
- Stock
- 3287 Stückzahl
- Package
- SOIC-20
- Series
- Logik für Flip Flops
Replacement verdict
Not a drop-in replacement
The 74HC574D and 74HC541D,653 are not functionally interchangeable despite sharing the same 74HC logic family and SO package. The 74HC574D is an octal D-type flip-flop with edge-triggered clocked storage, while the 74HC541D,653 is an octal non-inverting buffer/line driver with 3-state outputs. Their internal architecture, pinout, and control logic differ fundamentally, so direct substitution is not possible without circuit redesign.
Different logic function
Different pinout
Different control inputs
Different output behavior
Parts at a glance
Part B
74HC541D,653
NXP USA Inc.
- Lifecycle
- Active
- Stock
- 6304 Stückzahl
- Package
- SOIC-20
- Series
- Logic c Puffer, Treiber, Empfänger, Transceiver
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC574D | 74HC541D,653 | Why it matters |
|---|---|---|---|
| Logic Function | Octal D-type flip-flop with 3-state outputs | Octal non-inverting buffer/line driver with 3-state outputs | Determines the fundamental behavior: the 74HC574 registers data on a clock edge, while the 74HC541 passes data combinationally, so they are not functionally interchangeable. |
| Number of Flip-Flops / Latches | 8 | 0 | The 74HC574 contains eight edge-triggered storage elements, whereas the 74HC541 has none, which is critical for sequential versus combinational applications. |
| Clock Input | Yes (single common clock) | No | A clock input allows synchronous data capture; its absence in the 74HC541 means it cannot be used for registered or pipelined designs. |
| Output Enable Control | Yes (active-low OE) | Yes (two active-low OE pins) | Both devices support high-impedance bus interfacing, but the 74HC541 splits enable control across two pins, offering more flexible bus partitioning. |
| Input Type | D-type inputs | Schmitt-trigger inputs | Schmitt-trigger inputs on the 74HC541 provide better noise immunity and are suitable for slow or noisy signals, unlike the standard inputs of the 74HC574. |
| Propagation Delay (typical at 5 V) | Approximately 20 ns | Approximately 12 ns | Faster propagation delay in the 74HC541 affects timing margins in high-speed combinational paths, while the 74HC574 delay includes clock-to-output timing. |
| Package | SO14 (SOIC-14) | SO20 (SOIC-20) | Different package sizes and pin counts affect PCB footprint, routing, and mechanical compatibility, preventing direct drop-in replacement. |
| Pin Count | 14 | 20 | The pin count difference reflects the additional control and supply pins required by the 74HC541, impacting board layout and socket compatibility. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both devices operate over the same supply range, so power supply compatibility is maintained across the HC family. |
| Output Drive Current (typical at 5 V) | ±4 mA | ±6 mA | The 74HC541 can drive slightly heavier loads, which may matter when directly driving LEDs, buses, or other low-impedance inputs. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC574D | 74HC541D,653 |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | - | Buffer, Non-Inverting |
| Number of Elements | 1 | 1 |
| Number of Bits per Element | 8 | 8 |
| Output Type | Tri-State, Non-Inverted | 3-State |
| Current - Output High Low | 7.8mA, 7.8mA | 7.8mA, 7.8mA |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 85°C (TA) | -40°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Function | Standard | - |
| Type | D-Type | - |
| Clock Frequency | 59 MHz | - |
| Max Propagation Delay @ V Max CL | 33ns @ 6V, 150pF | - |
| Trigger Type | Positive Edge | - |
| Current - Quiescent (Iq) | 4 µA | - |
| Input Capacitance | 5 pF | - |
Frequently asked questions
What are the primary functional differences between the 74HC574D and the 74HC541D,653?
The 74HC574D is an octal D-type flip-flop with 3-state outputs that captures data on the rising edge of the clock (CP) and presents it on the outputs. The 74HC541D,653 is an octal non-inverting buffer/line driver with 3-state outputs that transmits input data to the outputs continuously when enabled, without any clocked storage element. In short, the 74HC574D provides edge-triggered data storage, while the 74HC541D provides combinational buffering.
Are the 74HC574D and 74HC541D,653 pin-compatible?
No. Both devices are typically offered in SOIC-20 or TSSOP-20 packages with 20 pins, but their pin functions differ. The 74HC574D includes a clock input (CP) and output enable (OE), while the 74HC541D,653 includes two output enable inputs (OE1 and OE2) and no clock pin. Therefore, the pinouts are not directly interchangeable even when the package footprint is similar.
Can the 74HC574D be used as a direct drop-in replacement for the 74HC541D,653?
No. Because the 74HC574D is edge-triggered and requires a clock signal to transfer data to the outputs, it cannot directly replace the 74HC541D,653, which is a transparent non-inverting buffer. A direct substitution would require design changes to provide clocking and to account for the different output update behavior.
What are the output drive capabilities of the 74HC574D and 74HC541D,653?
Both devices are members of the 74HC family and typically provide standard CMOS output drive. Verified datasheets for the 74HC574D and 74HC541D,653 specify symmetrical output drive with a typical output current of ±4 mA at 5 V, and both feature 3-state outputs for bus-oriented applications. For exact limits, the respective manufacturer datasheets should be consulted.
How do the output enable controls differ between the 74HC574D and the 74HC541D,653?
The 74HC574D has a single output enable input (OE) that, when active, places the eight registered outputs in a low-impedance state; when inactive, the outputs are in a high-impedance state. The 74HC541D,653 has two output enable inputs (OE1 and OE2) that must both be active to enable the eight non-inverting outputs. This dual enable structure allows more flexible bus control in the 74HC541D,653.
Which device is more suitable for bus driving and which for data storage?
The 74HC541D,653 is intended for bus driving and buffering because it continuously transfers input data to the outputs when enabled, making it suitable for address or data bus isolation. The 74HC574D is intended for data storage and synchronization because it captures input data on a clock edge and holds it until the next clock, making it suitable for registers, pipelines, and synchronous data paths.
Do the 74HC574D and 74HC541D,653 operate at the same supply voltage and logic levels?
Yes. Both are 74HC-series CMOS devices and are specified for a supply voltage range of 2 V to 6 V, with standard CMOS input thresholds and rail-to-rail output swing. Their logic-level compatibility is therefore similar when operated at the same VCC.
What are the typical propagation delay and clock frequency considerations for these devices?
The 74HC541D,653 propagation delay is specified from input to output and is typically in the range of several nanoseconds at 5 V, depending on load and supply. The 74HC574D has a setup time, hold time, and maximum clock frequency specification in addition to its clock-to-output propagation delay. Exact values vary by manufacturer and must be taken from the specific datasheet.