Part A
74HC574D
東芝電晶體與存儲
- Lifecycle
- Active
- Stock
- 3287 件
- Package
- SOIC-20
- Series
- 邏輯-觸發器
Replacement verdict
Not a drop-in replacement
The 74HC574D and 74HC595D,112 are not functionally interchangeable despite sharing the same 74HC CMOS logic family and SO-16 package. The 74HC574D is an octal D-type flip-flop with 3-state outputs intended for parallel data storage and bus interfacing, while the 74HC595D,112 is an 8-bit serial-in/parallel-out shift register with an integrated output latch and 3-state outputs intended for serial-to-parallel data conversion and I/O expansion. Their internal architectures, pin functions, and control signal sets differ fundamentally, so a direct drop-in substitution is not possible without redesigning the surrounding circuitry and control logic.
Different logic function
Different pinout
Different data interface
Different control signals
Parts at a glance
Part B
74HC595D,112
Nexperia美國公司
- Lifecycle
- Active
- Stock
- 3930 件
- Package
- SOIC-16
- Series
- 邏輯-位移暫存器
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 | 74HC595D,112 | Why it matters |
|---|---|---|---|
| Logic Function | Octal D-type flip-flop with 3-state outputs | 8-bit serial-in, serial/parallel-out shift register with output latches | Defines the fundamental operation; these devices are not functionally interchangeable as they perform different logic functions. |
| Output Type | 3-state (tri-state) parallel outputs | 3-state serial/parallel outputs with separate storage register | Determines how outputs can be connected to a bus and whether outputs can be shared or driven simultaneously. |
| Number of Pins | 20 | 16 | Pin count affects PCB footprint and package compatibility; different pin counts prevent direct drop-in replacement. |
| Data Input Interface | Parallel (8-bit D inputs) | Serial (single DS input with SHCP shift clock) | Determines how data is loaded into the device; parallel vs serial loading requires different host controller interfaces. |
| Clock Inputs | Single clock (CP) for all flip-flops | Two clocks: shift register clock (SHCP) and storage register clock (STCP) | Affects timing control and the ability to separate data shifting from output updating. |
| Output Latch / Storage Register | No separate storage register; flip-flops hold data directly | Separate 8-bit storage register with latch | A separate storage register allows outputs to remain stable while new data is shifted in, which is critical for cascaded or multiplexed designs. |
| Serial Data Output (Q7') | Not available | Available for cascading | Serial output enables cascading multiple devices to expand output count without additional host pins. |
| Output Enable Control | Output enable (OE) controls all 8 outputs | Output enable (OE) controls all 8 outputs | Both provide tri-state control, but the enable behavior interacts differently with the internal registers of each device. |
| Typical Application | Bus interface, data latching, register/buffer applications | LED drivers, GPIO expansion, serial-to-parallel conversion | Indicates the intended use case; substituting one for the other generally requires redesigning the interface and control logic. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both are HC-family CMOS devices with compatible supply ranges, so voltage compatibility is not a barrier to substitution. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC574D | 74HC595D,112 |
|---|---|---|
| Supplier | - | Nexperia USA Inc. |
| Series | 74HC | 74HC |
| Part Status | Active | Obsolete |
| Logic Type | - | Shift Register |
| Output Type | Tri-State, Non-Inverted | Tri-State |
| Number of Elements | 1 | 1 |
| Number of Bits per Element | 8 | 8 |
| Function | Standard | Serial to Parallel, Serial |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 85°C (TA) | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Type | D-Type | - |
| Clock Frequency | 59 MHz | - |
| Max Propagation Delay @ V Max CL | 33ns @ 6V, 150pF | - |
| Trigger Type | Positive Edge | - |
| Current - Output High Low | 7.8mA, 7.8mA | - |
| Current - Quiescent (Iq) | 4 µA | - |
| Input Capacitance | 5 pF | - |
Frequently asked questions
What are the primary functional differences between the 74HC574D and the 74HC595D,112?
The 74HC574D is an octal D-type flip-flop with 3-state outputs, used for parallel data storage and buffering. The 74HC595D,112 is an 8-bit serial-in, parallel-out shift register with a parallel output latch and 3-state outputs, used for serial-to-parallel data conversion and I/O expansion.
Can the 74HC574D and 74HC595D,112 be used interchangeably in a design?
No. The 74HC574D requires parallel data inputs and a clock to latch all bits simultaneously, while the 74HC595D,112 accepts serial data and a shift clock, then transfers data to a parallel latch. Their pin functions and control logic differ, so they are not pin-compatible or functionally interchangeable.
Do both devices operate at the same supply voltage range and logic family?
Yes. Both are 74HC-series high-speed CMOS devices. The 74HC574D and 74HC595D,112 typically operate over a supply voltage range of 2.0 V to 6.0 V, with standard CMOS input thresholds and 3-state outputs.
What is the package type for the 74HC574D and 74HC595D,112?
Both devices are commonly offered in SO16 (SOIC-16) packages. The 74HC574D suffix typically indicates a SO16 package, and the 74HC595D,112 suffix also indicates a SO16 package in tape and reel packaging.
How many output pins does each device provide?
The 74HC574D provides eight 3-state parallel outputs (Q0–Q7). The 74HC595D,112 also provides eight 3-state parallel outputs (QA–QH), plus a serial data output (QH') for cascading multiple devices.
Which device is better suited for expanding microcontroller I/O with minimal pin count?
The 74HC595D,112 is better suited for I/O expansion because it requires only three control lines (serial data, shift clock, latch clock) to drive eight outputs and can be cascaded for additional outputs. The 74HC574D requires eight parallel data lines plus a clock and output enable, consuming more microcontroller pins.
Do both devices have 3-state output capability?
Yes. Both the 74HC574D and 74HC595D,112 feature 3-state outputs controlled by an output enable (OE) pin, allowing the outputs to be placed in a high-impedance state for bus sharing or power reduction.
What is the maximum operating frequency for these devices?
Both devices are specified for operation up to approximately 50 MHz at 5 V supply, depending on load conditions and manufacturer. Exact maximum frequency should be verified from the specific manufacturer datasheet, as timing parameters can vary slightly between sources.