74VHC244FT vs 74VHCT74ATTR

Cette comparaison détaillée des composants 74VHC244FT et 74VHCT74ATTR vous offre un aperçu précieux de leurs spécifications et caractéristiques clés. Nous abordons en détail les facteurs importants, notamment la conformité RoHS, le statut REACH, la série, le mode de montage, le type de boîtier et d'autres caractéristiques pertinentes. La présentation côte à côte des différences simplifie la sélection des composants et vous permet de choisir plus facilement la meilleure option pour votre application spécifique.

Technical review by ETEI Component Engineering Source: manufacturer documentation

Replacement verdict

Not a drop-in replacement

The 74VHC244FT and 74VHCT74ATTR are functionally incompatible devices that cannot serve as substitutes for one another. The 74VHC244FT is an octal non-inverting buffer/line driver with 3-state outputs, while the 74VHCT74ATTR is a dual D-type flip-flop with preset and clear. Their differing logic functions, channel configurations, pin assignments, and package footprints make direct replacement impossible without substantial circuit redesign.

Different logic function Different channel count Different pin configuration Different package footprint

Parts at a glance

Part A

74VHC244FT

Toshiba Semiconductor et stockage

Lifecycle
Active
Stock
2156 PCS
Package
TSSOP-20
Series
Logique - Buffers, lecteurs, récepteurs, émetteurs - récepteurs
+Nomenclature Demande de devis

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 74VHCT74ATTR Why it matters
Logic Function Octal Buffer/Line Driver (3-state) Dual D-Type Flip-Flop These devices perform completely different logic functions, so they are not functionally interchangeable in a circuit.
Logic Family VHC (Very High Speed CMOS) VHCT (Very High Speed CMOS with TTL-compatible inputs) VHCT inputs are TTL-voltage compatible, while VHC inputs are CMOS-level; this affects interfacing with other logic families.
Number of Channels 8 (octal) 2 (dual) Channel count determines how many signals the device can process simultaneously.
Output Type 3-state (tri-state) buffer Standard push-pull (flip-flop outputs) Tri-state outputs allow bus sharing, whereas standard outputs cannot be tied together without contention.
Supply Voltage Range 2.0 V to 5.5 V 4.5 V to 5.5 V The narrower supply range of the VHCT device limits its use in low-voltage systems.
Propagation Delay (typical) ~3.5 ns at 5 V ~5.0 ns at 5 V Propagation delay affects maximum operating frequency and timing margins in synchronous designs.
Input Type CMOS-level inputs TTL-compatible inputs TTL-compatible inputs allow direct interfacing with TTL logic without level shifting.
Package TSSOP-20 TSSOP-14 Different pin counts and footprints prevent direct drop-in replacement on the same PCB pad layout.
Operating Temperature Range -40 °C to +85 °C -40 °C to +85 °C Both devices share the same industrial temperature range, suitable for similar environments.

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Full specification comparison

Use manufacturer datasheets as the final authority.

Specification 74VHC244FT 74VHCT74ATTR
Supplier - STMicroelectronics
Series 74VHC 74VHCT
Part Status Active Obsolete
Function - Set(Preset) and Reset
Type - D-Type
Output Type 3-State Complementary
Number of Elements 2 2
Number of Bits per Element 4 1
Clock Frequency - 140 MHz
Max Propagation Delay @ V Max CL - 8.8ns @ 5V, 50pF
Trigger Type - Positive Edge
Current - Output High Low 8mA, 8mA 8mA, 8mA
Voltage - Supply 2V ~ 5.5V 4.5V ~ 5.5V
Current - Quiescent (Iq) - 2 µA
Input Capacitance - 6 pF
Operating Temperature -40°C ~ 125°C (TA) -55°C ~ 125°C (TA)
Mounting Type Surface Mount Surface Mount
Logic Type Buffer, Non-Inverting -

Frequently asked questions

What are the primary functional differences between the 74VHC244FT and the 74VHCT74ATTR?

The 74VHC244FT is an octal non-inverting buffer/line driver with 3-state outputs, while the 74VHCT74ATTR is a dual D-type positive-edge-triggered flip-flop with preset and clear. They serve entirely different logic functions and are not functionally equivalent.

Are the 74VHC244FT and 74VHCT74ATTR pin-to-pin compatible?

No. The 74VHC244FT is typically supplied in a TSSOP-20 package with 20 pins, while the 74VHCT74ATTR is supplied in a TSSOP-14 package with 14 pins. The pin counts, pin assignments, and package footprints differ, so they cannot be interchanged on the same PCB land pattern.

What logic families do the 74VHC244FT and 74VHCT74ATTR belong to?

The 74VHC244FT belongs to the VHC (Very High Speed CMOS) family, while the 74VHCT74ATTR belongs to the VHCT (Very High Speed CMOS with TTL-compatible inputs) family. VHCT devices feature input thresholds compatible with TTL logic levels, whereas VHC devices have CMOS-level input thresholds.

Can the 74VHC244FT and 74VHCT74ATTR operate from the same supply voltage?

Both devices are specified for a nominal supply voltage of 5 V, typically operating over a range of 4.5 V to 5.5 V. However, the VHCT74ATTR's TTL-compatible inputs allow it to interface with 5 V TTL logic directly, while the VHC244FT requires CMOS-level input swings for optimal performance.

What are the output drive capabilities of the 74VHC244FT compared to the 74VHCT74ATTR?

The 74VHC244FT is specified with a symmetric output drive of ±8 mA at 5 V, making it suitable for bus driving and line driving applications. The 74VHCT74ATTR provides a standard output drive of ±8 mA at 5 V as well, but its primary function is logic storage rather than bus driving.

Do both devices support 3-state outputs?

No. The 74VHC244FT features 3-state outputs controlled by two active-low output enable pins, allowing the outputs to be placed in a high-impedance state for bus sharing. The 74VHCT74ATTR has standard push-pull outputs and does not provide a high-impedance state.

What are the typical propagation delays for the 74VHC244FT and 74VHCT74ATTR?

At 5 V supply, the 74VHC244FT typically exhibits a propagation delay of approximately 3.8 ns. The 74VHCT74ATTR typically exhibits a propagation delay of approximately 5.0 ns from clock to output. These values are typical and subject to variation per manufacturer datasheet conditions.

Are the 74VHC244FT and 74VHCT74ATTR interchangeable in a design?

No. Because they perform different logic functions, have different pin counts, and belong to different logic families with different input threshold characteristics, they cannot be used as substitutes for one another without a complete redesign of the circuit and PCB layout.

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