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Texas Instruments SN74AHC138RGYR
- Part No.:
- SN74AHC138RGYR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-VFQFN Exposed Pad
- Datasheet:
-
SN74AHC138RGYR.pdf
- Description:
- IC DECODER/DEMUX 1X3:8 16VQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,185
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Product details
Overview
SN74AHC138RGYR from Texas Instruments is a 3-line to 8-line decoder/demultiplexer in a 16-pin VQFN (RGY) package, operating from 2V to 5.5V VCC, with propagation delays as low as 5.7 ns at 5V and ±8 mA output drive capability. It features three enable inputs (two active-low, one active-high) for cascading and demultiplexing, and is designed for high-speed memory decoding and data-routing systems.
For engineers reviewing the SN74AHC138RGYR datasheet, SN74AHC138RGYR pinout, SN74AHC138RGYR application, or SN74AHC138RGYR equivalent, key selection criteria include its 16-pin VQFN thermal performance (RθJA = 39°C/W), input transition rate tolerance (20 ns/V at 5V), latch-up immunity (>250 mA), and compatibility with 3.3V/5V mixed-signal logic interfaces.
Technical Context
The SN74AHC138RGYR implements positive-logic binary decoding with three address inputs (A0–A2) selecting one of eight active-low outputs (Y0–Y7), controlled by three independent enables: G1 (active-high), G2A and G2B (both active-low). Its architecture allows direct 24-line expansion without external inverters and supports demultiplexing via enable-as-data-input functionality.
It uses advanced CMOS AHC technology to achieve rail-to-rail output swing, low static current (≤40 μA at 5.5V), and robust ESD protection (2000V HBM, 1000V CDM), while maintaining consistent timing across its −40°C to +85°C industrial temperature range and 2V–5.5V supply window.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2V to 5.5V - supports direct interface with both 3.3V and 5V logic families without level shifters |
| tPLH/tPHL (5V, 15pF) | 5.7 ns max - enables sub-10 ns system-level address decode in high-speed memory subsystems |
| IOH/IOL | ±8 mA at 5V - drives standard TTL loads or multiple 74AHC inputs with margin |
| Input Thresholds | VIH = 3.85V, VIL = 1.65V at VCC = 5.5V - ensures noise-immune switching in noisy industrial environments |
| Power Dissipation Cap. | 13 pF - low dynamic power consumption supports dense PCB layouts with minimal heat buildup |
| ESD Rating | 2000V HBM, 1000V CDM - meets IEC 61000-4-2 Level 2 for board-level handling reliability |
| Latch-up Immunity | >250 mA per JESD17 - prevents destructive failure during transient overcurrent events |
Pinout & Package
The SN74AHC138RGYR is housed in a 4mm × 3.5mm VQFN-16 (RGY) package with an exposed thermal pad that may be connected to GND or left floating - no connection to other signals or supplies is permitted.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0, A1, A2 | Binary address inputs | Select one of eight outputs; logic levels directly map to Y0–Y7 activation per function table |
| G1 | Active-high enable | Enables decoding only when high; used as primary global enable or data input in demux mode |
| G2A, G2B | Active-low enables | Both must be low to activate outputs; simplifies cascading with inverted control signals |
| Y0–Y7 | Active-low decoded outputs | Only one asserted low per valid address/enable combination; open-drain behavior not supported |
| VCC | Positive supply | Single 2V–5.5V rail powers all logic; decoupling near pin required for <10 ns edge integrity |
| GND | Ground reference | Return path for all I/O and supply currents; thermal pad connection improves thermal resistance to 39°C/W |
Key Features
| Feature | Design Value |
|---|---|
| Three enable inputs | Enables seamless 24-line decoding without external inverters and flexible demultiplexing via G1/G2A/G2B routing |
| High-speed propagation | 5.7 ns tPLH/tPHL at 5V allows integration into sub-10 ns memory access cycles without adding system delay |
| Rail-to-rail CMOS outputs | VOH ≥ 4.4V and VOL ≤ 0.1V at 5V ensure full logic swing compatibility with downstream 74AHC/ACT/LVC devices |
| Low input capacitance | Ci = 10 pF max reduces loading on upstream drivers and preserves signal integrity in fanout-heavy designs |
| Industrial temperature range | −40°C to +85°C operation validated across voltage and load conditions - suitable for embedded control and instrumentation |
Applications
| Memory Address Decoding | Peripheral Select Logic |
|---|---|
Use Scenario: Selecting one of eight SRAM or Flash memory banks in a microcontroller-based data acquisition system. IC Role / Device Role / Timing Role: 3-bit address decoder translating CPU address lines into individual chip-enable signals for parallel memory devices. Use Value: Eliminates need for discrete gates or larger CPLDs; 5.7 ns delay ensures memory access timing budgets remain intact even at 100+ MHz bus speeds. | Use Scenario: Routing UART, SPI, or GPIO peripherals in an industrial PLC I/O module with shared address/data bus. IC Role / Device Role / Timing Role: Demultiplexer converting 3-bit peripheral ID into dedicated select lines for up to eight I/O expanders or sensor interfaces. Use Value: Enables single-bus control of multiple peripherals with deterministic latency and no software overhead for address translation. |
| LED Matrix Row Driver | Test Equipment Signal Routing |
Use Scenario: Driving rows of an 8×8 LED matrix in multiplexed display applications using constant-current sink drivers. IC Role / Device Role / Timing Role: Active-low output decoder synchronizing row activation with column scan timing in real-time display controllers. Use Value: Delivers precise, glitch-free row selection with 8 mA sink capability per output - sufficient to directly drive common cathode LED rows. | Use Scenario: Configuring signal paths in automated test equipment (ATE) where DUT interface channels are dynamically assigned. IC Role / Device Role / Timing Role: High-reliability logic switch enabling or disabling up to eight analog/digital measurement paths under microprocessor control. Use Value: Latch-up immunity (>250 mA) and ESD robustness (2000V HBM) prevent field failures during probe contact or hot-swap events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 3-to-8 decoder applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LV138APWR | Lower VCC range (1.65V–5.5V); slower max speed (10.1 ns at 5V); higher input capacitance (12 pF) | Better suited for ultra-low-voltage mixed-signal systems; less ideal for sub-10 ns timing-critical memory decode | Choose when operating below 2V or prioritizing lower static power over speed |
| 74HC138D | Same pinout but HC logic family: higher ICC (80 μA vs. 40 μA), slower propagation (23 ns at 4.5V), no AHC-level ESD rating | Compatible for legacy 5V-only designs with relaxed timing; lacks AHC's noise immunity and drive strength | Use only in cost-sensitive, non-industrial applications where 23 ns delay is acceptable |
Compared with SN74LV138APWR and 74HC138D, the SN74AHC138RGYR delivers the fastest propagation, lowest power at high speed, and highest ruggedness - making it optimal for new industrial, test, and high-density memory designs requiring guaranteed sub-10 ns decode latency and robust operation.
Availability
SN74AHC138RGYR is available at Aetrix Electronics and suitable for memory subsystems, industrial I/O modules, LED display controllers, and automated test equipment requiring stable component supply and verified thermal performance in compact VQFN packaging.
Supply support for SN74AHC138RGYR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader delivering analog, embedded processing, and logic solutions with emphasis on reliability, precision, and energy efficiency.
The SN74AHC138RGYR belongs to TI's AHC logic family, engineered for high-speed, low-power decoding and demultiplexing in memory and data-path applications where timing predictability and noise immunity are critical.
FAQ
What is the maximum operating frequency supported by the SN74AHC138RGYR?
The SN74AHC138RGYR does not specify a clock frequency, as it is a combinational logic device. Its usable switching rate is determined by propagation delay and load capacitance: at 5V with 15pF load, tPLH/tPHL is 5.7 ns, supporting effective address decode rates exceeding 100 MHz in well-designed systems. The SN74AHC138RGYR must be operated within its recommended VCC (2V–5.5V) and temperature (−40°C to +85°C) ranges for guaranteed timing.
Can the SN74AHC138RGYR be used as a demultiplexer?
Yes - the SN74AHC138RGYR functions as a 1-to-8 demultiplexer when one enable input (e.g., G1) is used as the data input and A0–A2 serve as select lines. All outputs are active-low, so the selected path asserts low while others remain high. This configuration is explicitly supported in the functional description and requires no external components. The SN74AHC138RGYR maintains full timing and drive specifications in demux mode.
Is the thermal pad on the SN74AHC138RGYR package required to be soldered to ground?
No - the thermal pad on the SN74AHC138RGYR VQFN package may be connected to GND or left electrically floating, per TI's datasheet guidance. It must never be connected to any signal or supply net other than GND. Soldering it to a solid GND plane improves thermal resistance (RθJA = 39°C/W), but floating is acceptable if board layout constraints prohibit grounding.
Does the SN74AHC138RGYR support mixed-voltage interfacing between 3.3V and 5V systems?
Yes - the SN74AHC138RGYR operates from 2V to 5.5V and has TTL-compatible input thresholds (VIL = 1.65V, VIH = 3.85V at VCC = 5.5V), allowing reliable interfacing with both 3.3V outputs (which exceed VIH minimum) and 5V logic. Its outputs swing rail-to-rail, so SN74AHC138RGYR driven from 3.3V VCC produces ~3.3V VOH, compatible with 3.3V receivers.
What is the recommended bypassing strategy for the SN74AHC138RGYR?
TI recommends a 0.1 μF ceramic capacitor placed as close as possible to the VCC pin (Pin 16) and GND (Pin 8), with short, low-inductance traces. For systems with multiple SN74AHC138RGYR devices or high-frequency switching, add a bulk 4.7 μF tantalum or ceramic capacitor nearby. The SN74AHC138RGYR's low ICC (≤40 μA) reduces average current demand, but fast edges require local high-frequency decoupling to suppress supply bounce.
SN74AHC138RGYR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHC
- Package/Case:
- 16-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Decoder/Demultiplexer
- Circuit:
- 1 x 3:8
- Independent Circuits:
- 1
- Current - Output High, Low:
- 8mA, 8mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 2V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-VQFN (4x3.5)
SN74AHC138RGYR FAQ
1.How can I place an order for SN74AHC138RGYR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHC138RGYR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for SN74AHC138RGYR reliable?
The price and inventory of SN74AHC138RGYR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHC138RGYR is usually 5 days.
3.What payment methods are accepted for SN74AHC138RGYR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHC138RGYR transactions.
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4.How is shipping managed for SN74AHC138RGYR?
SN74AHC138RGYR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHC138RGYR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for SN74AHC138RGYR?
For technical support, including SN74AHC138RGYR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHC138RGYR requirements.
6.How does Aetrix verify that SN74AHC138RGYR is sourced from the original manufacturer or authorized distributors?
All SN74AHC138RGYR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74AHC138RGYR meets industry standards.
7.What is the process for return or replacement of SN74AHC138RGYR?
All SN74AHC138RGYR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHC138RGYR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The SN74AHC138RGYR part is unused and in its original packaging.
Return procedure for SN74AHC138RGYR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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