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Renesas 74HCT138FPEL-E
- Part No.:
- 74HCT138FPEL-E
- Manufacturer:
- Renesas
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- -
- Datasheet:
-
74HCT138FPEL-E.pdf
- Description:
- 3-TO-8 LINE DECODER/DEMUX
- Quantity:
- Payment:
- Shipping:
Inventory:4,000
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Product details
Overview
74HCT138FPEL-E from Renesas Electronics is a 3-to-8 line decoder/demultiplexer with active-low outputs, three binary select inputs (A, B, C), and three enable inputs (G1 high-active, G2A/G2B low-active). It operates at VCC = 4.5–5.5 V, delivers tPLH/tPHL ≤ 38 ns over –40°C to +85°C, supports fanout of 10 LSTTL loads, and features low quiescent ICC ≤ 40 µA. It is used in address decoding for microcontroller-based memory systems.
For engineers reviewing the 74HCT138FPEL-E datasheet, 74HCT138FPEL-E pinout, 74HCT138FPEL-E application, or 74HCT138FPEL-E equivalent, key selection criteria include enable logic configuration (1 high + 2 low enables), propagation delay consistency across all eight outputs, output drive capability under 4 mA load, and SOP-16 JEITA package compatibility with standard 1.27 mm pitch PCB layouts.
Technical Context
The 74HCT138FPEL-E implements TTL-compatible CMOS logic with Schmitt-trigger noise immunity on enable inputs. Its decoding logic fully resolves all eight output states based on simultaneous evaluation of A/B/C and the three enable conditions - no internal latching or state retention is present.
Propagation delays are specified identically for select-input-to-output (A/B/C → Yn) and enable-input-to-output (G1, G2A, G2B → Yn) paths, ensuring deterministic timing in cascaded decoder trees. Output rise/fall times remain ≤19 ns under CL = 50 pF, supporting reliable operation in synchronous bus environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - Ensures compatibility with standard 5 V TTL/CMOS logic rails and stable operation across industrial supply tolerances. |
| tpd (max) | 44 ns - Guarantees worst-case decode latency for real-time address selection in 8-bit microcontroller systems. |
| IOL / IOH | ±4 mA - Supports direct driving of multiple LSTTL inputs without external buffers in bus interface applications. |
| VIL / VIH | 0.8 V / 2.0 V - Matches TTL input thresholds, enabling seamless interfacing with legacy 74LS-series logic. |
| ICC (max) | 40 µA - Enables low-static-power operation in always-on control logic or battery-backed subsystems. |
| Operating Temp | –40°C to +85°C - Qualified for industrial ambient environments without derating. |
| Input Capacitance | 10 pF - Minimizes loading on upstream drivers and preserves signal integrity in high-speed routing. |
Pinout & Package
SOP-16 pin package (JEITA PRSP0016DH-B, Renesas code FP-16DAV), 5.5 mm × 10.06 mm body, 1.27 mm lead pitch, Ni/Pd/Au plating, tape-and-reel packaging (EL: 2,000 pcs/reel).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (A) | Binary Select Input | LSB of 3-bit address; referenced to GND/VCC for unambiguous logic level interpretation. |
| 2 (B) | Binary Select Input | Middle bit of 3-bit address; must be stable before enable assertion to avoid glitched outputs. |
| 3 (C) | Binary Select Input | MSB of 3-bit address; determines Y4–Y7 vs. Y0–Y3 group activation when enables are active. |
| 4 (G2A) | Active-Low Enable | First enable condition; device disabled if high; requires pull-down or active driver for cascade control. |
| 5 (G2B) | Active-Low Enable | Second enable condition; OR'd with G2A - both must be low for decode operation. |
| 6 (G1) | Active-High Enable | Third enable condition; must be high for output activation; used for hierarchical chip select partitioning. |
| 7 (Y7) | Active-Low Output | Complement of decoded "111" state; sinks current when selected; open-collector compatible via external pull-up. |
| 8 (GND) | Ground Reference | Primary return path for all input/output currents; requires low-inductance connection to system ground plane. |
| 9 (VCC) | Supply Voltage | Power rail for internal logic and output drivers; bypass capacitor (0.1 µF) required within 5 mm of this pin. |
| 10 (Y0) | Active-Low Output | Complement of decoded "000" state; asserted only when A=B=C=0 and all enables satisfied. |
| 11 (Y1) | Active-Low Output | Complement of decoded "001" state; used for peripheral chip select in 3-wire address expansion. |
| 12 (Y2) | Active-Low Output | Complement of decoded "010" state; provides dedicated enable for I/O port or timer module. |
| 13 (Y3) | Active-Low Output | Complement of decoded "011" state; commonly assigned to UART or SPI peripheral selection. |
| 14 (Y4) | Active-Low Output | Complement of decoded "100" state; enables higher-address peripherals such as ADC or DAC interfaces. |
| 15 (Y5) | Active-Low Output | Complement of decoded "101" state; supports memory-mapped register access in embedded controllers. |
| 16 (Y6) | Active-Low Output | Complement of decoded "110" state; used for interrupt controller or watchdog enable signaling. |
Key Features
| Feature | Design Value |
|---|---|
| Three Enable Inputs (1 high + 2 low) | Enables hierarchical decoding: G1 controls major block, G2A/G2B allow fine-grained sub-block selection without additional logic gates. |
| tPLH/tPHL ≤ 38 ns (–40°C to +85°C) | Ensures predictable setup/hold timing margins in 12 MHz CPU bus cycles with no added wait states. |
| Fanout of 10 LSTTL Loads | Drives up to ten 74LS-series inputs directly - eliminates need for buffer ICs in mixed-logic designs. |
| VIL = 0.8 V, VIH = 2.0 V | Guarantees interoperability with legacy 74LS and modern 74HCT families without level-shifting circuitry. |
| ICC ≤ 40 µA (max) | Reduces total system standby power in multi-decoder configurations - critical for energy-constrained industrial controllers. |
Applications
| Memory Address Decoding | Peripheral Selection Logic |
|---|---|
Use Scenario: Selecting one of eight RAM/ROM chips in an 8-bit microcontroller system using A0–A2 address lines. IC Role / Device Role / Timing Role: 3-to-8 line decoder mapping low-order address bits to individual chip-select signals with deterministic 44 ns max latency. Use Value: Eliminates discrete NAND gate networks, reduces PCB area by >30%, and guarantees monotonic output transitions during address changes. |
Use Scenario: Assigning dedicated chip-select lines to UART, SPI, I²C, ADC, DAC, GPIO expander, timer, and interrupt controller in an MCU subsystem. IC Role / Device Role / Timing Role: Demultiplexer converting 3-bit peripheral ID bus into eight independent active-low enables synchronized to clock domain. Use Value: Enables single-cycle peripheral arbitration without software overhead; supports hot-plug detection via enable pin monitoring. |
| Cascaded Decoder Tree | Logic State Machine Control |
Use Scenario: Building a 4-to-16 or 5-to-32 decoder using two or four 74HCT138FPEL-E devices with shared select lines and daisy-chained enables. IC Role / Device Role / Timing Role: Modular decoder unit providing standardized enable propagation (G1→G2A/G2B) and identical delay characteristics across stages. Use Value: Maintains timing coherence across all 16/32 outputs - essential for synchronous FPGA configuration or PLD bootloading. |
Use Scenario: Generating eight distinct control signals for sequential state transitions in a hardware finite-state machine (e.g., motor commutation, protocol handshaking). IC Role / Device Role / Timing Role: Combinational logic block translating 3-bit state register output into mutually exclusive active-low control pulses. Use Value: Provides glitch-free, race-free output assertion due to simultaneous evaluation of all inputs - no internal metastability risk. |
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 |
|---|---|---|---|
| SN74HCT138DR (Texas Instruments) | Identical logic function, same 4.5–5.5 V VCC range, but SOIC-16 package (JEDEC MS-012) with 1.27 mm pitch and slightly different thermal resistance (θJA = 110°C/W vs. Renesas' 125°C/W). | Valid for drop-in replacement in existing SOIC footprints; TI version has tighter VOH min (4.2 V @ VCC = 4.5 V) but identical VOL max (0.33 V). | Select when sourcing from TI-authorized channels or requiring TI's extended temp-grade variants (–55°C to +125°C). |
| 74VHC138M (ON Semiconductor) | Higher speed (tpd = 10.5 ns typ), wider VCC range (2–5.5 V), but lower output drive (IOL = 8 mA vs. 4 mA) and no guaranteed operation below 4.5 V in industrial temp range. | Better suited for mixed-voltage 3.3 V/5 V systems; not recommended for legacy 5 V-only designs requiring strict 74HCT-level noise margins. | Select when optimizing for propagation delay in new 3.3 V–5 V hybrid designs and verifying layout compatibility with VHC-series input thresholds. |
Compared with SN74HCT138DR and 74VHC138M, the 74HCT138FPEL-E offers best-in-class industrial temperature stability at 5 V, guaranteed TTL-compatible thresholds, and Renesas' long-term supply commitment for embedded OEM programs - making it optimal for cost-sensitive, volume-manufactured industrial controllers.
Availability
74HCT138FPEL-E is available at Aetrix Electronics and suitable for memory address decoding, peripheral selection logic, cascaded decoder trees, and logic state machine control requiring stable component supply across multi-year production cycles.
Supply support for 74HCT138FPEL-E 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
Renesas Electronics Corporation is a global semiconductor leader specializing in microcontrollers, analog, power, and timing solutions for industrial, automotive, and infrastructure markets.
The HD74HCT138 product line delivers TTL-compatible CMOS logic ICs optimized for robust 5 V system integration, with emphasis on noise immunity, consistent timing, and long-lifecycle support in factory automation and legacy-compatible embedded designs.
FAQ
What is the maximum operating temperature range for the 74HCT138FPEL-E?
The 74HCT138FPEL-E is rated for continuous operation from –40°C to +85°C under recommended supply conditions (VCC = 4.5–5.5 V). This range is validated per Renesas' industrial-grade qualification standards and applies to all electrical parameters in the datasheet, including propagation delay and output drive strength. The 74HCT138FPEL-E maintains full functionality across this range without derating.
Does the 74HCT138FPEL-E support 3.3 V logic levels?
No, the 74HCT138FPEL-E is not designed for reliable 3.3 V operation. Its recommended VCC range is strictly 4.5–5.5 V, and its input thresholds (VIH = 2.0 V min, VIL = 0.8 V max) are optimized for 5 V TTL compatibility. At 3.3 V supply, the 74HCT138FPEL-E may exhibit undefined output behavior, increased propagation delay variation, and failure to meet VOH/VOL specifications - use 74VHC138 or 74LVC138 for 3.3 V systems.
How many enable inputs does the 74HCT138FPEL-E have, and what are their logic polarities?
The 74HCT138FPEL-E has three enable inputs: G1 is active-high, while G2A and G2B are both active-low. All three enables must be simultaneously satisfied (G1 = H, G2A = L, G2B = L) for any output to become active. This configuration allows flexible hierarchical decoding - for example, G1 can serve as a master block enable while G2A/G2B select sub-functions within that block.
Can the 74HCT138FPEL-E drive standard LS-TTL loads directly?
Yes, the 74HCT138FPEL-E is specified to drive up to 10 LSTTL loads per output, verified at IOL = 4 mA and VOL ≤ 0.33 V over the full temperature range. Its output structure meets LSTTL voltage and current requirements without external buffers, enabling direct interface with legacy 74LS-series components in mixed-technology systems.
What package type is used for the 74HCT138FPEL-E, and is it RoHS compliant?
The 74HCT138FPEL-E uses a SOP-16 package per JEITA standard PRSP0016DH-B (Renesas code FP-16DAV), with 1.27 mm lead pitch and Ni/Pd/Au plating. It complies with EU RoHS Directive 2011/65/EU, as confirmed by Renesas' environmental compliance documentation - no lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE substances above threshold limits.
74HCT138FPEL-E Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- 74HCT
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- Decoder/Demultiplexer
- Circuit:
- 1 x 3:8
- Independent Circuits:
- 1
- Current - Output High, Low:
- 4mA, 4mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
74HCT138FPEL-E FAQ
1.How can I place an order for 74HCT138FPEL-E through Aetrix?
Please submit a Request for Quotation (RFQ) for 74HCT138FPEL-E 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 74HCT138FPEL-E reliable?
The price and inventory of 74HCT138FPEL-E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74HCT138FPEL-E is usually 5 days.
3.What payment methods are accepted for 74HCT138FPEL-E?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74HCT138FPEL-E transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74HCT138FPEL-E?
74HCT138FPEL-E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74HCT138FPEL-E 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 74HCT138FPEL-E?
For technical support, including 74HCT138FPEL-E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74HCT138FPEL-E requirements.
6.How does Aetrix verify that 74HCT138FPEL-E is sourced from the original manufacturer or authorized distributors?
All 74HCT138FPEL-E 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 74HCT138FPEL-E meets industry standards.
7.What is the process for return or replacement of 74HCT138FPEL-E?
All 74HCT138FPEL-E units undergo pre-shipment inspection (PSI). If there is an issue with 74HCT138FPEL-E, 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 74HCT138FPEL-E part is unused and in its original packaging.
Return procedure for 74HCT138FPEL-E:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
74HCT138FPEL-E Tags
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SN74HC138DR
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TC7SB3157CFU,LF(CT
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P3S0200GMX
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SN74CB3Q3257RGYR
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TCA9543APWR
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TCA9546APWR
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SN74HC138N
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