Part A
74HC573D
東芝電晶體與存儲
- Lifecycle
- Active
- Stock
- 3424 件
- Package
- SOIC-14
- Series
- 邏輯-鎖存器
Replacement verdict
Not a drop-in replacement
The 74HC573D and 74HC595D,118 are not functionally interchangeable despite sharing the same 74HC CMOS logic family and SO16 package. The 74HC573D is a transparent D-type latch with a single latch-enable control, while the 74HC595D,118 is a serial-in/parallel-out shift register with an internal storage register and separate shift and latch clocks. Their pin functions, control logic, and data flow architectures differ fundamentally, so direct substitution is not possible without redesigning the surrounding circuitry.
Different logic function
Different control interface
Different data flow
Different pin assignment
Parts at a glance
Part B
74HC595D,118
恩智浦美國股份有限公司。
- Lifecycle
- Active
- Stock
- 2450 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 | 74HC573D | 74HC595D,118 | Why it matters |
|---|---|---|---|
| Logic Function | Octal D-type transparent latch with 3-state outputs | 8-bit serial-in, serial/parallel-out shift register with output latches | Defines the fundamental operation; a latch and a shift register are not functionally interchangeable in most designs. |
| Data Input Type | Parallel (8-bit D inputs) | Serial (single DS input) with shift register | Determines how data is loaded; parallel loading versus serial shifting requires different control logic and pin usage. |
| Output Type | Parallel 3-state (8 outputs) | Parallel 3-state (8 outputs) plus serial QH' output | The 595 provides an extra serial output for cascading, while the 573 does not, affecting expandability. |
| Number of Pins | 20 | 16 | Different package pin counts mean incompatible footprints and PCB layouts. |
| Latch/Register Control | Latch Enable (LE) and Output Enable (OE) | Shift Register Clock (SHCP), Storage Register Clock (STCP), Output Enable (OE), Shift Register Clear (MR) | Control signal requirements differ significantly, so driving circuitry and timing must be redesigned. |
| Propagation Delay (typical at 5V) | ~14 ns (tPHL/tPLH) | ~16 ns (shift clock to output) | Timing differences affect maximum operating frequency and setup/hold margins in synchronous systems. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both support the same HC-family voltage range, so power supply compatibility is not a differentiator. |
| Output Drive Current | ±6 mA (at 5V) | ±6 mA (at 5V) | Identical drive strength means neither offers an advantage for directly driving loads. |
| Operating Temperature Range | -40°C to +125°C | -40°C to +125°C | Same industrial temperature range, so environmental suitability is equivalent. |
| Package Type | SO20 (SOIC-20) | SO16 (SOIC-16) | Different package sizes and pin counts prevent direct drop-in replacement on the same PCB footprint. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC573D | 74HC595D,118 |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | D-Type Latch | Shift Register |
| Output Type | Tri-State | Tri-State |
| Number of Elements | - | 1 |
| Number of Bits per Element | - | 8 |
| Function | - | Serial to Parallel, Serial |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Circuit | 8:8 | - |
| Independent Circuits | 1 | - |
| Delay Time - Propagation | 26ns | - |
| Current - Output High Low | 7.8mA, 7.8mA | - |
Frequently asked questions
What is the main functional difference between the 74HC573D and the 74HC595D,118?
The 74HC573D is an octal D-type transparent latch with 3-state outputs, used for temporary data storage and bus driving. The 74HC595D,118 is an 8-bit serial-in, parallel-out shift register with a storage register and 3-state outputs, used for serial-to-parallel data conversion and I/O expansion.
Are the 74HC573D and 74HC595D,118 pin-compatible?
No. The 74HC573D is typically supplied in a 20-pin package (e.g., SO20), while the 74HC595D,118 is supplied in a 16-pin package (e.g., SO16). Pin counts and pin functions differ, so they are not drop-in replacements.
Can the 74HC573D and 74HC595D,118 be used together in the same design?
Yes. They serve complementary roles: the 74HC595D,118 can convert serial data to parallel, and the 74HC573D can latch and drive that parallel data onto a bus or peripheral. Both are compatible with standard HC-family logic levels when used within specified supply and temperature ranges.
What are the output drive capabilities of the 74HC573D and 74HC595D,118?
Both devices are HC-family CMOS logic parts. Their datasheets specify standard HC-family output drive currents, typically ±4 mA to ±6 mA per output at a defined supply voltage and temperature, depending on the manufacturer and test conditions. Always consult the specific manufacturer datasheet for exact ratings.
Do both the 74HC573D and 74HC595D,118 have 3-state outputs?
Yes. The 74HC573D has 3-state outputs controlled by an output enable pin. The 74HC595D,118 also has 3-state outputs controlled by an output enable pin, allowing the parallel outputs to be placed in a high-impedance state.
Which device is better for expanding microcontroller I/O?
The 74HC595D,118 is generally preferred for I/O expansion because it requires only three control lines (serial data, shift clock, latch clock) to drive eight outputs. The 74HC573D requires a parallel data bus and control lines, making it more suitable for bus latching than for serial I/O expansion.
What supply voltage range do the 74HC573D and 74HC595D,118 support?
Both are 74HC-family devices and typically operate from 2 V to 6 V, with guaranteed operation commonly specified from 2 V to 6 V across the full temperature range. Verify the exact limits in the manufacturer datasheet for the specific part number and package.
Are the 74HC573D and 74HC595D,118 available in surface-mount packages?
Yes. The 74HC573D is commonly available in SO20 surface-mount packages. The 74HC595D,118 is commonly available in SO16 surface-mount packages. Package suffixes and exact mechanical dimensions should be confirmed from the manufacturer datasheet.