In the world of "Little Logic," sometimes you need more than just a simple gate. You need control.
The Texas Instruments SN74LVC1G240DRYR is a workhorse component found in everything from smartphones to industrial control boards. It combines a high-current driver, a logic inverter, and a digital switch into one tiny package.
But why use a "3-State" buffer? And what makes the "DRY" package special? This guide breaks down the datasheet and applications of this essential logic chip.
Table of Contents
- 1. Decoding the Part Number: Specs & Features
- 2. How It Works: Inverting with Control
- 3. The "DRY" Package Advantage (SON-6)
- 4. Key Applications: Voltage Translation & Isolation
- 5. Conclusion
1. Decoding the Part Number: Specs & Features
TI part numbers are descriptive. Here is the breakdown for SN74LVC1G240DRYR:
The Breakdown Matrix
- SN74: Standard Prefix for TI Commercial Logic.
- LVC: Low-Voltage CMOS. Optimized for 1.65V to 5.5V operation.
- 1G: Single Gate. Contains only one logic function per chip.
- 240: Function Code for Inverting Buffer / Driver with 3-State Output.
- DRY: Package Code for SON-6 (Small Outline No-lead).
- R: Tape & Reel packaging (for automated assembly).
Key Specifications
| Feature | Specification | Impact |
|---|---|---|
| Vcc Range | 1.65V to 5.5V | Extremely flexible; works with 1.8V, 3.3V, and 5V logic. |
| Drive Strength | 32 mA (@ 4.5V) | High current drive; can directly drive LEDs or Relays. |
| Input Tolerance | 5.5V | Inputs can handle 5V even when Vcc is 3.3V (Down Translation). |
| Ioff Protection | Yes | Output is disabled when Vcc = 0V (prevents backflow current). |
| Propagation Delay | ~4 ns | Very fast switching speed. |
2. How It Works: Inverting with Control
The SN74LVC1G240 is not just a NOT gate. It has an Output Enable ($\overline{OE}$) pin.
- The Inverter Part: Whatever logic level enters Input A, the opposite comes out of Output Y.
- The 3-State Part: This action only happens if $\overline{OE}$ is LOW. If $\overline{OE}$ is HIGH, the output turns "off".
The Truth Table
| Control Input ($\overline{OE}$) | Data Input (A) | Output (Y) | State |
|---|---|---|---|
| L | L | H | Active (Inverting) |
| L | H | L | Active (Inverting) |
| H | X | Z | High Impedance (Off) |
Understanding "High-Z"
High-Z (High Impedance) means the pin is effectively disconnected from the circuit. It is neither Logic High (Vcc) nor Logic Low (GND).
- Why is this useful? It allows multiple chips to share the same data wire (bus) without fighting each other (short circuiting). Only one chip is enabled ($\overline{OE}$ Low) at a time.
3. The "DRY" Package Advantage (SON-6)
The DRY suffix indicates the SON-6 (Small Outline No-lead) package.
- Size: 1.45 mm x 1.00 mm.
- Height: 0.6 mm.
- Footprint: Significantly smaller than the standard SOT-23 (DBV) package.
Why choose DRY? It is ideal for space-constrained devices like smartwatches, earbuds, or dense SSD controller boards. However, note that it is harder to hand-solder or rework than SOT-23 due to the pads being underneath the chip body.
4. Key Applications: Voltage Translation & Isolation
5V to 3.3V Down-Translation
Because the inputs are 5.5V Tolerant (even when Vcc is lower), you can power this chip with 3.3V but send 5V signals into Input A.
- Result: The output will swing between 0V and 3.3V. This safely converts a 5V sensor signal for a 3.3V microcontroller input.
Ioff Signal Isolation
The Ioff feature is critical for power sequencing. If you turn off power to the SN74LVC1G240 (Vcc = 0V), the inputs and outputs enter a high-impedance state.
- Benefit: They will not drain current from connected live circuits via protection diodes. This is perfect for isolating different power domains on a complex board.
5. Conclusion
The SN74LVC1G240DRYR is a fundamental building block for modern electronics. Whether you need to fix a logic polarity issue, isolate a noisy signal, or translate voltages in a tiny wearable device, this SON-6 chip delivers robust performance with minimal board space.
Sourcing Logic Components Building a dense PCB? Visit Aichiplink.com to search for SN74LVC1G240DRYR and other TI Little Logic gates.
Written by Jack Elliott from AIChipLink.
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Frequently Asked Questions
What is the SN74LVC1G240 used for?
It is a single-channel inverting buffer with 3-state output used for signal control and isolation.
What does “3-state output” mean?
The output can be High, Low, or High-Impedance (High-Z) when disabled.
What voltage levels does SN74LVC1G240 support?
It operates from 1.65V to 5.5V and supports 5V-tolerant inputs.
What is the DRY package?
DRY refers to a SON-6 ultra-small package, ideal for space-constrained designs.
Can SN74LVC1G240 be used for voltage level translation?
Yes. It is commonly used for 5V-to-3.3V down-translation.
