Part A
74HC573D
Toshiba Semiconductor and Storage
- Lifecycle
- Active
- Stock
- 3424 PCS
- Package
- SOIC-14
- Series
- Lógica - Latches
Replacement verdict
Compatible functional replacement candidate
The 74HC574D and 74HC573D are functionally interchangeable in most designs, sharing identical logic function, package, and supply voltage characteristics. The primary distinction lies in their input/output pin arrangement, which requires careful PCB layout verification before substitution.
Logic Function
High match
Package Type
High match
Supply Voltage
High match
Pin Configuration
Validation required
Parts at a glance
Part B
74HC574D
Toshiba Semiconductor and Storage
- Lifecycle
- Active
- Stock
- 3287 PCS
- Package
- SOIC-20
- Series
- Lógica - 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 | 74HC574D | 74HC573D | Why it matters |
|---|---|---|---|
| Logic Type | D-Type Flip-Flop (edge-triggered) | D-Type Transparent Latch (level-sensitive) | Determines whether data is captured on a clock edge or passes through while the enable is active, which fundamentally changes timing behavior and substitutability. |
| Trigger Mechanism | Positive-edge triggered clock (CP) | Level-sensitive latch enable (LE) | Edge-triggered devices hold data stable between clock edges, while transparent latches allow output to follow input, affecting race conditions and timing design. |
| Output Type | 3-State (tri-state) non-inverting | 3-State (tri-state) non-inverting | Both offer tri-state outputs for bus interfacing, but the control signal differs (OE for both, but data capture differs). |
| Number of Channels | 8 (octal) | 8 (octal) | Both are 8-bit devices, so bus width compatibility is identical. |
| Control Inputs | Clock (CP) and Output Enable (OE) | Latch Enable (LE) and Output Enable (OE) | Different control signal names and functions mean pin-compatible but not functionally identical replacements. |
| Propagation Delay (typical at 5V) | ~18 ns (CP to Q) | ~18 ns (LE to Q) | Similar delay values, but the reference signal differs, affecting setup/hold timing calculations. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Identical supply range ensures both can operate in the same 3.3V or 5V systems. |
| Package | SO14 (D package) | SO20 (D package) | Different pin counts and package sizes mean they are not drop-in replacements on the same PCB footprint. |
| Pin Count | 20 pins | 20 pins | Same pin count but different pinout assignments for control signals, requiring layout changes. |
| Operating Temperature Range | -40°C to +125°C | -40°C to +125°C | Identical temperature ratings allow use in the same industrial and automotive environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC573D | 74HC574D |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | D-Type Latch | - |
| Circuit | 8:8 | - |
| Output Type | Tri-State | Tri-State, Non-Inverted |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Independent Circuits | 1 | - |
| Delay Time - Propagation | 26ns | - |
| Current - Output High Low | 7.8mA, 7.8mA | 7.8mA, 7.8mA |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Function | - | Standard |
| Type | - | D-Type |
| Number of Elements | - | 1 |
| Number of Bits per Element | - | 8 |
| 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 is the main functional difference between the 74HC574D and the 74HC573D?
The 74HC574D is an octal D-type flip-flop with 3-state outputs that captures data on the rising edge of the clock (CP). The 74HC573D is an octal D-type transparent latch with 3-state outputs that is transparent when the latch-enable (LE) input is HIGH and latches data when LE goes LOW. In short, the 574 is edge-triggered, while the 573 is level-triggered (transparent latch).
Are the 74HC574D and 74HC573D pin-compatible?
Yes. Both devices are offered in the same SOIC-20 (D) package and use the same 20-pin pinout: pins 1–8 are the 3-state outputs (Q0–Q7), pins 9 and 19 are the ground and supply pins respectively, pins 10 and 20 are the control inputs (OE and CP for the 574; OE and LE for the 573), and pins 11–18 are the data inputs (D0–D7). Because the pinout is identical, they can share the same PCB footprint, but the control-input function differs.
Can the 74HC574D and 74HC573D be used interchangeably in a design?
Not unconditionally. Although they are pin-compatible, their control logic differs: the 574 updates on a clock edge, whereas the 573 is transparent while LE is HIGH. A direct substitution is only valid if the surrounding circuit is designed for the corresponding edge-triggered or transparent-latch behavior and the timing, setup, hold, and propagation requirements are re-verified against the manufacturer datasheet.
What are the output drive and supply voltage specifications for both devices?
Both the 74HC574D and 74HC573D are HC-family CMOS devices typically specified for a supply voltage range of 2.0 V to 6.0 V, with standard 74HC output drive of ±4 mA at 4.5 V (and typically ±5.2 mA at 6.0 V) per output. Exact limits, including absolute maximum ratings and derating, must be confirmed from the specific manufacturer datasheet, as parameters can vary slightly between vendors.
Do both devices have 3-state outputs?
Yes. Both the 74HC574D and 74HC573D provide 3-state outputs controlled by an output-enable (OE) input. When OE is inactive, the outputs are placed in a high-impedance state, allowing the devices to be connected to a shared bus. The OE polarity and exact enable/disable behavior should be verified in the manufacturer datasheet for the specific part number.
Which device is better for bus-oriented data transfer?
Both are commonly used for bus interfacing because they offer 3-state outputs. The choice depends on the required capture behavior: the 74HC574D is preferred when data must be captured synchronously on a clock edge, while the 74HC573D is preferred when a transparent latch is needed to hold data while the enable is active. Neither is universally "better"; selection should be based on the timing and control scheme of the target design.
What are the typical operating temperature ranges for the 74HC574D and 74HC573D?
Standard commercial-grade versions of both devices are typically specified for an operating temperature range of −40 °C to +85 °C, while industrial-grade versions may extend to −40 °C to +125 °C. The exact range depends on the manufacturer and the specific ordering code, so the datasheet for the exact part number must be consulted.
Are the 74HC574D and 74HC573D available in other package options besides SOIC-20?
Yes. Both functions are commonly offered in multiple package types, including SOIC-20 (often denoted by the "D" suffix), TSSOP-20, and sometimes DIP-20 or other surface-mount variants, depending on the manufacturer. The "D" suffix specifically indicates the SOIC-20 package in many manufacturer naming conventions, but package availability should be confirmed from the specific vendor's ordering information.