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Texas Instruments SN74HCS138QDYYRQ1
- Part No.:
- SN74HCS138QDYYRQ1
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- SOT-23-16 Thin, SOT-23 Variant
- Datasheet:
-
SN74HCS138QDYYRQ1.pdf
- Description:
- AUTOMOTIVE 3-LINE TO 8-LINE DECO
- Quantity:
- Payment:
- Shipping:
Inventory:2,990
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Product details
Overview
SN74HCS138QDYYRQ1 from Texas Instruments is an automotive-grade 3-to-8 line decoder/demultiplexer with Schmitt-trigger inputs, operating from 2 V to 6 V supply, delivering ±7.8-mA output drive at 6 V, and featuring typical ICC of 100 nA for ultra-low-power memory address decoding in engine control units.
For engineers reviewing the SN74HCS138QDYYRQ1 datasheet, SN74HCS138QDYYRQ1 pinout, SN74HCS138QDYYRQ1 application, or SN74HCS138QDYYRQ1 equivalent, key selection criteria include AEC-Q100 Grade 1 qualification (–40°C to +125°C), hysteresis-enabled noise immunity, wettable-flank SOT-23-THN package compatibility with AOI, and cascading support via three strobe inputs (G2, G1, G0).
Technical Context
The SN74HCS138QDYYRQ1 implements a high-speed silicon-gate CMOS 3:8 decoder with three address inputs (A2–A0) and three independent strobe inputs (G2, active-high; G1/G0, active-low) that collectively force all eight outputs high when asserted. Its functional mode table confirms strict one-hot active-low output behavior only when all strobes are inactive and address lines are valid.
Schmitt-trigger inputs provide hysteresis (ΔVT = 0.6 V min at 6 V), enabling robust operation with slow-rising/falling signals and rejecting noise up to ±0.3 V peak-to-peak. Outputs are balanced CMOS push-pull with matched sourcing/sinking capability, supporting 50-pF load capacitance while maintaining tpd ≤ 16 ns (6 V, –40°C to 125°C).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2 V to 6 V - supports direct interface with 3.3-V and 5-V automotive microcontrollers without level shifting |
| Operating Temperature | –40°C to +125°C - qualified per AEC-Q100 Grade 1 for under-hood and powertrain applications |
| Output Drive | ±7.8 mA at 6 V - sufficient to directly drive multiple CMOS inputs or small LED indicators without external buffers |
| Supply Current (ICC) | Typical 100 nA at 6 V - enables always-on subsystems with negligible quiescent power impact |
| Hysteresis (ΔVT) | 0.6 V min at 6 V - rejects common-mode noise on long PCB traces or harness wiring in vehicle networks |
| Propagation Delay | 7 ns typ (6 V, TA = 25°C) - meets timing budgets for real-time memory selection in ADAS sensor hubs |
| Input Leakage | ±100 nA max at 6 V - ensures stable logic states even with high-impedance pull-up/down resistors (e.g., 100 kΩ) |
Pinout & Package
SN74HCS138QDYYRQ1 uses the SOT-23-THN (16-pin) package with 4.20 mm × 2.00 mm body size and wettable flanks for automated optical inspection (AOI) compatibility. Thermal pad is not present in this variant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | A0 | LSB address input - selects output Y0/Y1/Y2/Y3 when G0=G1=L, G2=H |
| 2 | A1 | Mid-bit address input - determines output group (Y0–Y3 vs Y4–Y7) with A0 |
| 3 | A2 | MSB address input - final bit selecting specific output among eight |
| 4 | G0 | Active-low strobe - disables all outputs (forces high) when logic low |
| 5 | G1 | Active-low strobe - cascading enable for multi-chip decoding trees |
| 6 | G2 | Active-high strobe - primary global enable; must be high for decode function |
| 7 | Y7 | Active-low decoded output - sinks current when A2A1A0 = 111 and strobes inactive |
| 8 | GND | Ground reference - return path for all input leakage and output sink currents |
| 9 | Y6 | Active-low decoded output - asserts only when A2A1A0 = 110 and strobes inactive |
| 10 | Y5 | Active-low decoded output - used for chip select in dual-memory configurations |
| 11 | Y4 | Active-low decoded output - enables peripheral I/O expansion in body control modules |
| 12 | Y3 | Active-low decoded output - routes data to CAN transceiver configuration registers |
| 13 | Y2 | Active-low decoded output - selects ADC channel multiplexer in battery management systems |
| 14 | Y1 | Active-low decoded output - activates LIN transceiver sleep/wake control lines |
| 15 | Y0 | Active-low decoded output - default boot device selector in infotainment SoC startup |
| 16 | VCC | Positive supply - powers internal logic and output drivers; requires local 0.1-μF bypass capacitor |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q100 Grade 1 qualification | Validated for continuous operation from –40°C to +125°C ambient, meeting automotive powertrain reliability requirements |
| Schmitt-trigger inputs | Provides 0.6 V minimum hysteresis at 6 V, eliminating need for external RC filters on noisy harness-connected signals |
| Wettable-flank SOT-23-THN | Enables reliable AOI solder-joint inspection without X-ray, reducing manufacturing defect escape in Tier-1 production |
| Three independent strobe inputs | Allows hierarchical decoding across up to eight devices using G2 as master enable and G1/G0 for sub-group selection |
| Ultra-low ICC (100 nA typ) | Supports >10-year battery life in always-on telematics modules with periodic wake-up events |
Applications
| Engine Control Unit (ECU) Memory Mapping | ADAS Sensor Hub Data Routing |
|---|---|
Use Scenario: Selecting between flash, EEPROM, and SRAM chips sharing a common 16-bit data bus in a gasoline direct injection ECU. IC Role / Device Role / Timing Role: 3-to-8 decoder providing chip-select signals synchronized to microcontroller address bus transitions. Use Value: Reduces GPIO count by 5 pins versus discrete logic, while Schmitt inputs tolerate crankshaft position sensor EMI coupling onto address lines. | Use Scenario: Routing SPI commands from a central vision processor to eight radar transceivers in a 77-GHz front-end module. IC Role / Device Role / Timing Role: Demultiplexer using G2 as frame-sync enable and A2–A0 to address individual radar ICs within time-sliced command windows. Use Value: Enables deterministic <16 ns propagation delay per channel, meeting ISO 26262 ASIL-B timing constraints for sensor fusion latency. |
| Body Control Module (BCM) I/O Expansion | Battery Management System (BMS) Cell Monitoring |
Use Scenario: Expanding microcontroller GPIOs to drive 16 door-lock actuators, window motors, and mirror controls via shared enable lines. IC Role / Device Role / Timing Role: Decoder driving high-side switches with active-low outputs directly interfacing N-channel MOSFET gates. Use Value: ±7.8-mA drive capability eliminates external buffer stages, reducing BOM cost and PCB area by 32% versus discrete transistor solutions. | Use Scenario: Selecting among 8 cell voltage measurement channels in a 96-cell EV traction battery pack. IC Role / Device Role / Timing Role: Address decoder enabling analog front-end multiplexers to sequentially sample individual cell pairs. Use Value: 2-V minimum supply allows direct connection to isolated 3.3-V domain, avoiding extra LDOs while maintaining 125°C junction temperature margin. |
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 |
|---|---|---|---|
| SN74HCS138DQ1 | SOIC-16 package (9.9 mm × 3.9 mm); no wettable flanks; RθJA = 122.2°C/W | Preferred for manual rework or legacy through-hole-compatible designs; higher thermal resistance limits high-density layouts | Select when board-level repairability or compatibility with existing SOIC footprints is required |
| SN74LV138AQPWRQ1 | Lower VCC range (1.65 V to 5.5 V); LV-CMOS process; 32 mA drive at 5 V; no Schmitt inputs | Optimized for low-voltage MCU interfaces but lacks noise immunity for harness-connected signals | Choose only if system operates strictly below 5.5 V and noise environment is controlled (e.g., inside ECU enclosure) |
Compared with SN74HCS138DQ1, SN74HCS138QDYYRQ1 offers 57% smaller footprint and AOI-ready solder joints, while versus SN74LV138AQPWRQ1 it provides essential hysteresis for unshielded automotive wiring-making it the sole choice for under-hood decoding where EMI immunity is non-negotiable.
Availability
SN74HCS138QDYYRQ1 is available at Aetrix Electronics and suitable for engine control units, ADAS sensor hubs, body control modules, and battery management systems requiring stable component supply across automotive production lifecycles.
Supply support for SN74HCS138QDYYRQ1 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 company specializing in analog and embedded processing technologies, with leadership in automotive electronics since 1980.
The SN74HCS138QDYYRQ1 belongs to TI's HCS logic family designed specifically for AEC-Q100-compliant automotive signal routing, emphasizing ultra-low power, noise resilience, and manufacturability in high-reliability vehicle systems.
FAQ
What automotive qualification does SN74HCS138QDYYRQ1 meet?
SN74HCS138QDYYRQ1 is AEC-Q100 qualified for automotive applications with Grade 1 temperature rating (–40°C to +125°C ambient), HBM ESD Level 2 (±4 kV), and CDM ESD Class C6 (±1.5 kV). These qualifications are verified per TI's production test flow and documented in the SCLS811D datasheet revision history.
Does SN74HCS138QDYYRQ1 support cascading with other decoders?
Yes, SN74HCS138QDYYRQ1 supports cascading via its three strobe inputs: G2 (active-high), G1 (active-low), and G0 (active-low). For example, connecting G2 of a downstream SN74HCS138QDYYRQ1 to Y0 of an upstream unit enables 3-to-64 line expansion without additional logic gates.
What is the purpose of Schmitt-trigger inputs in SN74HCS138QDYYRQ1?
The Schmitt-trigger inputs in SN74HCS138QDYYRQ1 provide hysteresis (ΔVT ≥ 0.6 V at 6 V), allowing reliable operation with slow-rising signals (e.g., from mechanical switches or long harness runs) and rejecting noise spikes up to ±0.3 V peak-to-peak-critical for robust decoding in electrically noisy vehicle environments.
Can SN74HCS138QDYYRQ1 drive LEDs directly?
Yes, SN74HCS138QDYYRQ1 can drive standard indicator LEDs directly: its ±7.8-mA output drive at 6 V supports typical 2–20 mA LED currents. Connect LED anode to VCC and cathode to any Yx output; the active-low output will sink current when selected, lighting the LED without external transistors.
Is the thermal pad connected in SN74HCS138QDYYRQ1's SOT-23-THN package?
No, the SN74HCS138QDYYRQ1 in SOT-23-THN (16-pin) packaging does not include a thermal pad. Unlike WQFN variants (BQB/WBQB), this variant relies on standard lead-frame conduction; thermal design should follow RθJA = 186.2°C/W per the datasheet's Table 6-4.
SN74HCS138QDYYRQ1 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCS
- Package/Case:
- SOT-23-16 Thin, SOT-23 Variant
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Decoder/Demultiplexer
- Circuit:
- 1 x 3:8
- Independent Circuits:
- 1
- Current - Output High, Low:
- 7.8mA, 7.8mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOT-23-THIN
SN74HCS138QDYYRQ1 FAQ
1.How can I place an order for SN74HCS138QDYYRQ1 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCS138QDYYRQ1 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 SN74HCS138QDYYRQ1 reliable?
The price and inventory of SN74HCS138QDYYRQ1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCS138QDYYRQ1 is usually 5 days.
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SN74HCS138QDYYRQ1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCS138QDYYRQ1 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 SN74HCS138QDYYRQ1?
For technical support, including SN74HCS138QDYYRQ1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCS138QDYYRQ1 requirements.
6.How does Aetrix verify that SN74HCS138QDYYRQ1 is sourced from the original manufacturer or authorized distributors?
All SN74HCS138QDYYRQ1 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 SN74HCS138QDYYRQ1 meets industry standards.
7.What is the process for return or replacement of SN74HCS138QDYYRQ1?
All SN74HCS138QDYYRQ1 units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCS138QDYYRQ1, 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 SN74HCS138QDYYRQ1 part is unused and in its original packaging.
Return procedure for SN74HCS138QDYYRQ1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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