Part A
74HC573D
Компания Toshiba Semiconductor и Storage
- Lifecycle
- Active
- Stock
- 3424 ПКС
- Package
- SOIC-14
- Series
- Логика - Заключения
Replacement verdict
Not a drop-in replacement
The 74HC573D and 74HC540D,652 are not functionally interchangeable despite sharing the 74HC logic family and SOIC-20 package. The 74HC573D is an octal D-type transparent latch with 3-state outputs, while the 74HC540D,652 is an octal inverting buffer/line driver with 3-state outputs. Their differing logic functions, output polarity, and pinout assignments prevent direct substitution without circuit redesign.
Different logic function
Different output polarity
Different pinout
Different input configuration
Parts at a glance
Part B
74HC540D,652
Компания NXP USA Inc.
- Lifecycle
- Active
- Stock
- 2550 ПКС
- Package
- SOIC-20
- Series
- Логика - буферы, драйверы, приемники, передатчики
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 | 74HC540D,652 | Why it matters |
|---|---|---|---|
| Logic Function | Octal D-type transparent latch with 3-state outputs | Octal buffer/line driver with 3-state outputs (inverting) | Determines the core function; a latch stores data while a buffer only drives signals, so they are not functionally interchangeable. |
| Output Type | Non-inverting | Inverting | Inverting vs non-inverting outputs change the logic polarity, directly affecting circuit behavior and substitutability. |
| Data Storage | Yes (transparent latch) | No | A latch can hold data between clock/enable events, while a buffer cannot, which is critical for timing and state retention. |
| Number of Bits | 8 | 8 | Both handle 8 channels, so bus width compatibility is maintained. |
| Control Inputs | Latch Enable (LE) and Output Enable (OE) | Output Enable (OE) only | Different control schemes affect how the device is driven and whether it can be substituted in existing designs. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both operate over the standard HC supply range, so voltage compatibility is equivalent. |
| Output Drive Current | ±6 mA (typical at 4.5 V) | ±6 mA (typical at 4.5 V) | Similar drive strength means comparable fan-out and load-driving capability. |
| Propagation Delay | Approximately 13 ns at 4.5 V | Approximately 8 ns at 4.5 V | Different delays affect timing margins in high-speed circuits and may require redesign if substituted. |
| Package | SO16 (SOIC-16) | SO16 (SOIC-16) | Same package footprint allows physical drop-in compatibility on the PCB. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Identical temperature ratings ensure both parts suit the same environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC573D | 74HC540D,652 |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | D-Type Latch | Buffer, Inverting |
| Number of Elements | - | 1 |
| Number of Bits per Element | - | 8 |
| Output Type | Tri-State | 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 | -40°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Circuit | 8:8 | - |
| Independent Circuits | 1 | - |
| Delay Time - Propagation | 26ns | - |
Frequently asked questions
What are the primary functional differences between the 74HC573D and the 74HC540D,652?
The 74HC573D is an octal D-type transparent latch with 3-state outputs, designed to capture and hold data. The 74HC540D,652 is an octal buffer/line driver with 3-state outputs, designed for signal buffering and driving. The 74HC573D features a latch enable (LE) and output enable (OE) control, while the 74HC540D,652 features two active-low output enable pins (OE1 and OE2) for independent control of two 4-bit groups.
Are the 74HC573D and 74HC540D,652 pin-to-pin compatible?
No. The 74HC573D and 74HC540D,652 have different pin configurations. The 74HC573D uses a standard 20-pin package with data inputs on one side and outputs on the other, plus LE and OE pins. The 74HC540D,652 uses a 20-pin package with a different pinout that includes two output enable pins and a flow-through architecture where inputs and outputs are arranged for simplified bus routing. They are not direct drop-in replacements.
Can the 74HC573D be used as a direct substitute for the 74HC540D,652 in an existing design?
No, not without design changes. The 74HC573D is a latch that holds data when LE is low, while the 74HC540D,652 is a buffer that continuously drives the output according to the input when enabled. Substitution would require changes to control logic, timing, and possibly PCB layout due to different pinouts.
What are the output drive capabilities of the 74HC573D and 74HC540D,652?
Both devices are from the 74HC family and typically provide standard CMOS output drive. Per manufacturer datasheets, both the 74HC573D and 74HC540D,652 have symmetrical output drive capability of ±6 mA at 5 V, which is suitable for driving low-power Schottky TTL loads or similar. For higher drive requirements, the 74HCT versions or other buffer families should be considered.
How do the control inputs differ between the 74HC573D and the 74HC540D,652?
The 74HC573D has a latch enable (LE) input and an output enable (OE) input. When LE is high, the latch is transparent; when LE goes low, data is latched. OE controls the 3-state outputs. The 74HC540D,652 has two active-low output enable inputs (OE1 and OE2) that control the 3-state outputs for two separate 4-bit groups. It does not have a latch function.
Which device is more suitable for bus-oriented applications?
The 74HC540D,652 is specifically designed for bus-oriented applications due to its flow-through pinout, which simplifies PCB layout, and its dual output enable pins that allow independent control of two 4-bit sections. The 74HC573D is also used in bus applications but is primarily intended for data latching and temporary storage.
What are the operating voltage and temperature ranges for these devices?
Both the 74HC573D and 74HC540D,652 typically operate over a supply voltage range of 2 V to 6 V and an ambient temperature range of -40 °C to +125 °C, as specified in manufacturer datasheets. These are standard specifications for the 74HC logic family.
Are the 74HC573D and 74HC540D,652 available in the same package type?
Both devices are commonly available in a 20-pin SOIC package (often denoted by the "D" suffix in the part number). However, the pinouts differ, so they are not interchangeable without PCB redesign. Other package options may exist, but the specified part numbers typically refer to the SOIC-20 package.