Part A
74VHC244FT
Toshiba Semiconductor và lưu trữ
- Lifecycle
- Active
- Stock
- 2156 PCS
- Package
- TSSOP-20
- Series
- Logic - Buffers, Drivers, Receivers, Transceivers
Replacement verdict
Not a drop-in replacement
The 74VHC244FT and 74VHCT573AMTC are functionally incompatible devices that cannot serve as substitutes for one another. The 74VHC244FT is a quad non-inverting buffer with 3-state outputs in a TSSOP-20 package, while the 74VHCT573AMTC is an octal D-type transparent latch with 3-state outputs in a TSSOP-20 package. Although both share the same package footprint and similar supply voltage ranges, their logic functions, channel counts, input threshold technologies, and pinout assignments differ fundamentally, making direct replacement impossible without circuit redesign.
Different logic function
Different channel count
Different input threshold technology
Different pinout assignment
Parts at a glance
Part B
74VHCT573AMTC
onsemi
- Lifecycle
- Active
- Stock
- 6318 PCS
- Package
- TSSOP-20
- Series
- Logic - Latches
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74VHC244FT | 74VHCT573AMTC | Why it matters |
|---|---|---|---|
| Logic Function | Octal Buffer/Line Driver with 3-State Outputs | Octal D-Type Transparent Latch with 3-State Outputs | These are fundamentally different logic functions; a buffer passes signals combinationally while a latch captures and holds data, so they are not functionally interchangeable. |
| Logic Family | VHC (Very High Speed CMOS) | VHCT (Very High Speed CMOS with TTL-Compatible Inputs) | VHCT inputs are TTL-voltage compatible, allowing direct interfacing with 5 V TTL logic, whereas VHC inputs are CMOS-level and may require level shifting. |
| Number of Channels | 8 (two 4-bit groups) | 8 | Both provide eight signal paths, but the 244 splits them into two independently enabled 4-bit groups while the 573 has a single latch-enable for all eight. |
| Control Inputs | Two active-low output enables (1OE, 2OE) | Latch Enable (LE) and Output Enable (OE) | The control scheme determines how the device is driven; the 244 uses enables for buffering, while the 573 uses LE to capture data and OE to gate outputs. |
| Output Type | 3-State | 3-State | Both offer high-impedance outputs for bus sharing, but the 573 additionally holds latched data when outputs are disabled. |
| Propagation Delay (typical) | ~3.5 ns at 5 V | ~6.5 ns at 5 V | Faster propagation delay affects maximum operating frequency and timing margins in synchronous systems. |
| Supply Voltage Range | 2.0 V to 5.5 V | 4.5 V to 5.5 V | The wider supply range of the VHC device supports low-voltage operation, while the VHCT device is restricted to 5 V systems. |
| Input Compatibility | CMOS-level inputs | TTL-level compatible inputs | TTL-compatible inputs allow the VHCT device to accept 5 V TTL signals directly, simplifying mixed-logic designs. |
| Package | TSSOP-20 | TSSOP-20 | Matching package footprints allow drop-in board placement, though the differing logic function still prevents direct substitution. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Identical temperature ratings mean both suit the same industrial and commercial environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74VHC244FT | 74VHCT573AMTC |
|---|---|---|
| Supplier | - | onsemi |
| Series | 74VHC | 74VHCT |
| Part Status | Active | Obsolete |
| Logic Type | Buffer, Non-Inverting | D-Type Transparent Latch |
| Circuit | - | 8:8 |
| Output Type | 3-State | Tri-State |
| Voltage - Supply | 2V ~ 5.5V | 4.5V ~ 5.5V |
| Independent Circuits | - | 1 |
| Delay Time - Propagation | - | 5.1ns |
| Current - Output High Low | 8mA, 8mA | 8mA, 8mA |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
| Number of Elements | 2 | - |
| Number of Bits per Element | 4 | - |
Frequently asked questions
What are the primary functional differences between the 74VHC244FT and the 74VHCT573AMTC?
The 74VHC244FT is an octal non-inverting buffer/line driver with 3-state outputs, organized as two 4-bit sections with separate output-enable pins. The 74VHCT573AMTC is an octal D-type transparent latch with 3-state outputs, featuring a latch-enable input and an output-enable input. The 74VHC244FT provides signal buffering without storage, while the 74VHCT573AMTC provides temporary data storage and latching.
Are the 74VHC244FT and 74VHCT573AMTC pin-to-pin compatible?
No. The 74VHC244FT is typically supplied in a TSSOP-20 package, while the 74VHCT573AMTC is supplied in a TSSOP-20 package as well, but the pin functions differ. The 74VHC244FT has two output-enable pins (1OE and 2OE) and no latch-enable pin, whereas the 74VHCT573AMTC has a latch-enable (LE) pin and an output-enable (OE) pin. Pin assignments and control logic are not interchangeable.
Can the 74VHC244FT be used as a direct drop-in replacement for the 74VHCT573AMTC in an existing design?
No. The 74VHC244FT lacks the data latching function of the 74VHCT573AMTC. Replacing a latch with a buffer would remove the ability to hold data, which is essential in latching applications. Additionally, the control pin functions and timing behavior differ, so a direct substitution is not possible without redesigning the circuit.
What are the logic family and operating voltage characteristics of these two devices?
The 74VHC244FT belongs to the VHC (Very High Speed CMOS) family, typically operating from 2.0 V to 5.5 V. The 74VHCT573AMTC belongs to the VHCT (Very High Speed CMOS with TTL-compatible inputs) family, also operating from 2.0 V to 5.5 V but with input thresholds compatible with TTL logic levels. Both are CMOS devices, but VHCT inputs allow direct interfacing with TTL outputs.
What are the output drive capabilities of the 74VHC244FT and 74VHCT573AMTC?
Both devices typically provide ±8 mA output drive at 5.0 V, which is standard for VHC/VHCT logic. This drive strength is suitable for driving moderate capacitive loads and standard logic inputs. For higher drive requirements, external buffers or drivers should be considered.
How do the propagation delays of the 74VHC244FT and 74VHCT573AMTC compare?
Both devices are high-speed CMOS logic. At 5.0 V, the 74VHC244FT typically has a propagation delay of approximately 3.5 ns to 5.5 ns. The 74VHCT573AMTC typically has a propagation delay of approximately 5.0 ns to 7.0 ns for the latch path. Exact values depend on load conditions and supply voltage, and should be verified from the respective manufacturer datasheets.
What are the typical applications for each device?
The 74VHC244FT is commonly used for signal buffering, bus driving, and increasing fan-out in digital systems. The 74VHCT573AMTC is used for data latching, address latching in microprocessor systems, and temporary data storage in bus-oriented applications. The choice depends on whether the system requires buffering or latching functionality.
Are the 74VHC244FT and 74VHCT573AMTC available in the same package type?
Both devices are available in TSSOP-20 packages, but this does not imply interchangeability. The 74VHC244FT may also be available in other packages such as SOIC-20 or DIP-20 depending on the manufacturer. The 74VHCT573AMTC is commonly offered in TSSOP-20 and SOIC-20. Always confirm the specific package suffix and pinout from the manufacturer datasheet before designing.