Part A
74VHC541FT
東芝セミコンダクター・アンド・ストレージ
- Lifecycle
- Active
- Stock
- 5516 個数
- Package
- TSSOP-20
- Series
- ロジック - バッファ、ドライバ、レシーバ、トランシーバ
Replacement verdict
Not a drop-in replacement
The 74VHC541FT and 74VHC240N are not functionally interchangeable. Although both are VHC-family octal buffers, the 74VHC541FT provides non-inverting 3-state outputs in a TSSOP-20 surface-mount package, while the 74VHC240N provides inverting 3-state outputs in a DIP-20 through-hole package. The differing output polarity, package footprint, and assembly process requirements prevent direct substitution without circuit and PCB redesign.
Different output polarity
Different package type
Different mounting style
Different pin function mapping
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74VHC541FT | 74VHC240N | Why it matters |
|---|---|---|---|
| Logic Function | Octal Buffer/Line Driver, non-inverting, 3-state | Octal Buffer/Line Driver, inverting, 3-state | Determines output polarity; a non-inverting buffer cannot directly replace an inverting buffer without logic changes. |
| Output Polarity | Non-inverting (Y = A) | Inverting (Y = A̅) | Affects signal phase; critical for functional substitutability in a circuit. |
| Enable Control | Two active-low output enables (OE1, OE2) | Two active-low output enables (1OE, 2OE), one per nibble | Determines how the outputs are gated; different grouping of enables changes control logic. |
| Package / Mounting | TSSOP-20 (surface mount) | DIP-20 (through-hole) | Footprint and assembly method differ; not drop-in compatible on the same PCB. |
| Pin Count | 20 | 20 | Same pin count but different pinout and package, so direct substitution is not possible. |
| Supply Voltage Range | 2.0 V to 5.5 V | 2.0 V to 5.5 V | Both support the same VHC operating range, allowing use in similar logic-level systems. |
| Output Drive Current | ±8 mA (at 5 V) | ±8 mA (at 5 V) | Similar drive strength means comparable fan-out and line-driving capability. |
| Propagation Delay | ~5.5 ns (typical at 5 V) | ~5.5 ns (typical at 5 V) | Similar speed performance; timing-critical designs may still need verification. |
| Operating Temperature | -40 °C to +85 °C | -40 °C to +85 °C | Same industrial temperature range supports use in similar environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74VHC541FT | 74VHC240N |
|---|---|---|
| Supplier | - | onsemi |
| Series | 74VHC | 74VHC |
| Part Status | Active | Obsolete |
| Logic Type | Buffer, Non-Inverting | Buffer, Inverting |
| Number of Elements | 1 | 2 |
| Number of Bits per Element | 8 | 4 |
| Output Type | 3-State | 3-State |
| Current - Output High Low | 8mA, 8mA | 8mA, 8mA |
| Voltage - Supply | 2V ~ 5.5V | 2V ~ 5.5V |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 85°C (TA) |
| Mounting Type | Surface Mount | Through Hole |
Frequently asked questions
What are the primary functional differences between the 74VHC541FT and the 74VHC240N?
The 74VHC541FT is an octal non-inverting buffer/line driver with 3-state outputs, while the 74VHC240N is an octal inverting buffer/line driver with 3-state outputs. The key difference is logic polarity: the '541 passes signals without inversion, whereas the '240 inverts each signal.
Are the 74VHC541FT and 74VHC240N pin-compatible?
No. The 74VHC541FT typically uses a TSSOP or similar surface-mount package, while the 74VHC240N is commonly supplied in a DIP package. Even in equivalent packages, the pinouts differ because the '541 has all inputs on one side and outputs on the other, whereas the '240 has inputs and outputs arranged in two 4-bit groups with opposite polarities.
Can the 74VHC541FT directly replace the 74VHC240N in an existing design?
No, not without design changes. The '541 is non-inverting and the '240 is inverting, so signal polarity would be reversed. Additionally, package and pinout differences prevent a drop-in replacement. Logic polarity and pin assignment must be validated against the target schematic.
Do both devices operate at the same supply voltage range?
Yes. Both the 74VHC541FT and 74VHC240N are VHC-family CMOS devices and are specified for a supply voltage range of 2.0 V to 5.5 V, with typical operation at 3.3 V or 5 V.
What are the output drive characteristics of these devices?
Both the 74VHC541FT and 74VHC240N provide standard VHC-family output drive, typically ±8 mA at 5 V VCC. They are intended for driving moderate capacitive loads and bus lines, and both feature 3-state outputs for bus-oriented applications.
Which device is better for bus driving applications?
Both are suitable for bus driving, but the choice depends on required signal polarity. The 74VHC541FT is used when non-inverted buffering is needed, while the 74VHC240N is used when inverted outputs are required. Both offer 3-state control for sharing a common bus.
Are the 74VHC541FT and 74VHC240N available in the same package types?
No. The 74VHC541FT is typically offered in surface-mount packages such as TSSOP, while the 74VHC240N is commonly available in DIP and sometimes SOIC packages. Package availability depends on the specific manufacturer and ordering part number.
What is the function of the output enable pins on these devices?
Both devices have output enable (OE) pins that place the outputs in a high-impedance state when deasserted, allowing the outputs to be connected to a shared bus without contention. On the 74VHC541FT, OE is typically active-low for both groups, while on the 74VHC240N, the two 4-bit groups have separate active-low enable pins.