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Texas Instruments SN74AHC138QWBQBRQ1
- Part No.:
- SN74AHC138QWBQBRQ1
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
SN74AHC138QWBQBRQ1.pdf
- Description:
- AUTOMOTIVE 2V-TO-5.5V 3-LINE TO
- Quantity:
- Payment:
- Shipping:
Inventory:2,998
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Product details
Overview
SN74AHC138QWBQBRQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive 3-line to 8-line decoder/demultiplexer with three enable inputs (G2, G̅1, G̅0), operating from 2V to 5.5V VCC, delivering 10.5ns propagation delay at 5V/50pF, and featuring balanced CMOS push-pull outputs for memory selection and chip-enable routing in engine control units.
For engineers reviewing the SN74AHC138QWBQBRQ1 datasheet, SN74AHC138QWBQBRQ1 pinout, SN74AHC138QWBQBRQ1 application, or SN74AHC138QWBQBRQ1 equivalent, key selection criteria include automotive temperature range (-40°C to +125°C), wettable-flank WQFN-16 package compatibility with AOI inspection, low-power static current (4–40 µA), and strict ESD ratings (HBM ±2000V, CDM ±1000V).
Technical Context
The SN74AHC138QWBQBRQ1 implements a positive-logic 3-to-8 decoder with active-high G2 and active-low G̅1/G̅0 strobes: all outputs go high when any strobe disables decoding, and only one output (Y0–Y7) drives low per address (A0–A2) when enabled. Its function table defines eight discrete output states controlled by three binary select lines and three independent enable conditions.
It uses standard CMOS inputs with ≤10 pF input capacitance and balanced push-pull outputs capable of sourcing/sinking ±8 mA at 5V, supporting direct interfacing with TTL and other AHC/AHCT logic families without level-shifting. The device includes internal clamp diodes and meets JESD17 latch-up immunity (>250 mA).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2V to 5.5V - supports single-supply operation across 2.5V, 3.3V, and 5V logic domains without external regulators |
| Propagation Delay | 10.5ns at VCC = 5V, CL = 50pF - enables timing-critical address decoding in real-time automotive subsystems |
| Output Drive | ±8mA at VCC = 5V - sufficient to directly drive multiple CMOS inputs or small LED indicators without buffers |
| Operating Temperature | –40°C to +125°C (Grade 1) - qualified for under-hood and transmission-control module environments |
| ESD Rating | HBM ±2000V, CDM ±1000V - exceeds AEC-Q100-002/-011 requirements for robustness in automated assembly and field operation |
| Static Supply Current | 4 µA typical, 40 µA max at VCC = 5.5V - minimizes quiescent power in always-on vehicle networks |
| Input Capacitance | ≤10 pF - reduces loading on upstream MCU GPIOs and preserves signal integrity at high switching rates |
Pinout & Package
SN74AHC138QWBQBRQ1 is packaged in a 3.5mm × 2.5mm wettable-flank WQFN-16 (WBQB) with exposed thermal pad, enabling automated optical inspection (AOI) of solder joints and enhanced thermal dissipation in compact automotive PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0, A1, A2 | Binary address inputs | Select one of eight outputs (Y0–Y7); must be terminated to VCC or GND-never left floating |
| G2 | Active-high enable input | Disables all outputs (forces high) when low; used as data input in demux mode |
| G̅1, G̅0 | Active-low enable inputs | Enable decoding only when both are low; reduce need for external inverters in cascaded designs |
| Y0–Y7 | Active-low decoded outputs | Only one output drives low per valid address; all others remain high-impedance active-high |
| VCC | Positive supply | Must be bypassed with 0.1µF capacitor placed adjacent to pin; supports 2V–5.5V operation |
| GND | Ground reference | Return path for all I/O and supply currents; recommended to use solid ground plane beneath thermal pad |
| Thermal Pad | Exposed die attach pad | May be connected to GND for improved thermal performance; not electrically functional if left floating |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q100 Grade 1 qualification | Validated for automotive use from –40°C to +125°C ambient, including thermal cycling and humidity testing |
| Wettable-flank WQFN package | Enables reliable AOI-based solder-joint inspection in high-volume SMT production lines |
| Three independent enable inputs | Allows hierarchical decoding (e.g., 32-line expansion with one external inverter) without added logic gates |
| Balanced CMOS push-pull outputs | Sources and sinks matched current (±8mA @ 5V), eliminating need for external pull-ups in open-drain configurations |
| Low dynamic power consumption | CPD = 87 pF enables predictable power estimation via P = CPD × VCC² × f, critical for battery-sensitive modules |
Applications
| Engine Control Unit (ECU) Memory Mapping | Advanced Driver Assistance Systems (ADAS) Sensor Hub |
|---|---|
|
Use Scenario: Selecting between multiple flash memory banks and peripheral registers in a multi-core automotive MCU. IC Role / Device Role / Timing Role: 3-to-8 decoder providing chip-select signals synchronized to address bus transitions. Use Value: Reduces MCU GPIO count by consolidating eight discrete CS lines into three address + three enable pins, saving PCB space and firmware complexity. |
Use Scenario: Routing camera, radar, and ultrasonic sensor data streams to shared processing lanes in domain controllers. IC Role / Device Role / Timing Role: Demultiplexer using G2 as data input and A0–A2 as channel selector to steer serial sensor payloads. Use Value: Enables time-division multiplexing of up to eight sensors onto a single interface bus while maintaining deterministic latency (≤10.5ns). |
| Body Control Module (BCM) I/O Expansion | Electric Powertrain Inverter Gate Driver Interface |
|
Use Scenario: Expanding limited microcontroller output pins to drive 16+ lighting zones, HVAC actuators, and door locks. IC Role / Device Role / Timing Role: Decoder driving high-side switches or optocouplers via Y0–Y7 outputs with active-low logic polarity. Use Value: Eliminates need for discrete transistors or dedicated I/O expanders, lowering BOM cost and board area in cost-sensitive body electronics. |
Use Scenario: Enabling individual gate drivers for six-phase motor inverters with isolated fault feedback paths. IC Role / Device Role / Timing Role: Strobe-controlled decoder selecting which IGBT/MOSFET driver receives PWM commands from central controller. Use Value: Provides hardware-level phase isolation and prevents shoot-through during startup/shutdown sequences via G̅1/G̅0 gating. |
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 |
|---|---|---|---|
| SN74LV138AQPWRQ1 | Lower VCC range (1.65V–5.5V), slower tPLH/tPHL (14.5ns @ 3.3V/15pF), same AEC-Q100 Grade 1 rating | Better suited for mixed-voltage 1.8V/3.3V systems but less ideal for timing-critical 5V legacy interfaces | Choose when system operates below 2V or requires lower dynamic power at reduced speed |
| MC74VHC138DT | Non-automotive grade, wider commercial temp range (–40°C to +85°C), identical pinout and logic function | Lacks AEC-Q100 qualification and extended 125°C operation; unsuitable for safety-critical powertrain modules | Acceptable for infotainment or comfort electronics where full automotive qualification is not mandated |
Compared with SN74LV138AQPWRQ1 and MC74VHC138DT, the SN74AHC138QWBQBRQ1 delivers optimal balance of speed (10.5ns), wide supply range (2V–5.5V), and full AEC-Q100 Grade 1 compliance-making it the preferred choice for engine, transmission, and ADAS control units requiring guaranteed operation at 125°C.
Availability
SN74AHC138QWBQBRQ1 is available at Aetrix Electronics and suitable for engine control units, ADAS sensor hubs, and body control modules requiring stable component supply across automotive production lifecycles.
Supply support for SN74AHC138QWBQBRQ1 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 specializing in analog, embedded processing, and automotive-grade logic solutions with over 50 years of automotive qualification experience.
The SN74AHC138QWBQBRQ1 belongs to TI's AHC-Q1 automotive logic family, engineered specifically for high-reliability decoding and demultiplexing in powertrain, chassis, and safety-critical vehicle subsystems.
FAQ
What is the maximum capacitive load SN74AHC138QWBQBRQ1 can drive while meeting datasheet timing specs?
The SN74AHC138QWBQBRQ1 is characterized for loads up to 50 pF across its full operating range. At 5V and 25°C, propagation delay remains ≤10.5ns with CL = 50pF. Driving larger capacitive loads increases delay nonlinearly and may violate setup/hold margins in synchronous systems; TI recommends limiting total load to 50pF unless re-characterized for specific conditions. The SN74AHC138QWBQBRQ1 datasheet specifies this limit in Section 5.6 Switching Characteristics.
Does SN74AHC138QWBQBRQ1 support 1.8V logic interfaces?
No, SN74AHC138QWBQBRQ1 has a minimum VCC of 2V per Recommended Operating Conditions (Section 5.3), and its input thresholds (VIH min = 1.5V at VCC = 2V) are not compatible with standard 1.8V logic levels. For 1.8V systems, consider SN74LV138AQPWRQ1, which supports 1.65V–5.5V operation and is also AEC-Q100 Grade 1 qualified. The SN74AHC138QWBQBRQ1 is not rated for reliable operation below 2V.
How should unused inputs be handled on SN74AHC138QWBQBRQ1?
All unused inputs (A0, A1, A2, G2, G̅1, G̅0) on SN74AHC138QWBQBRQ1 must be terminated to a valid logic level-either VCC or GND-to prevent floating nodes that cause excessive current draw, oscillation, or undefined output states. TI recommends 10kΩ pull-up or pull-down resistors for inputs that may be inactive during certain modes. Direct connection is acceptable for permanently fixed signals. Leaving any input unconnected violates Section 7.3.2 of the SN74AHC138QWBQBRQ1 datasheet.
Can SN74AHC138QWBQBRQ1 outputs be paralleled for higher current drive?
Yes-two or more outputs of the same SN74AHC138QWBQBRQ1 can be wired in parallel to increase sink/source capability, provided they are driven by identical address and enable conditions. This technique doubles effective drive strength (e.g., ±16mA at 5V) without violating absolute maximum ratings. However, outputs with conflicting logic states must never be shorted, as this causes destructive shoot-through current. The SN74AHC138QWBQBRQ1 Functional Modes table confirms identical behavior across Y0–Y7.
Is the thermal pad on SN74AHC138QWBQBRQ1 required to be connected to ground?
No-the thermal pad on SN74AHC138QWBQBRQ1 may be connected to GND for improved thermal performance or left electrically floating, as stated in Table 4-1 Pin Functions. TI does not require grounding; however, connecting it to a large copper pour tied to GND enhances heat dissipation and reduces junction temperature under sustained load. It must never be connected to VCC or signal nets. This guidance appears in the "Thermal pad(2)" footnote of the SN74AHC138QWBQBRQ1 pin configuration diagram.
SN74AHC138QWBQBRQ1 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHC
- Package/Case:
- 16-WFQFN 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 ~ 125°C
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 16-WQFN (2.5x3.5)
SN74AHC138QWBQBRQ1 FAQ
1.How can I place an order for SN74AHC138QWBQBRQ1 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHC138QWBQBRQ1 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 SN74AHC138QWBQBRQ1 reliable?
The price and inventory of SN74AHC138QWBQBRQ1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHC138QWBQBRQ1 is usually 5 days.
3.What payment methods are accepted for SN74AHC138QWBQBRQ1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHC138QWBQBRQ1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHC138QWBQBRQ1?
SN74AHC138QWBQBRQ1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHC138QWBQBRQ1 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 SN74AHC138QWBQBRQ1?
For technical support, including SN74AHC138QWBQBRQ1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHC138QWBQBRQ1 requirements.
6.How does Aetrix verify that SN74AHC138QWBQBRQ1 is sourced from the original manufacturer or authorized distributors?
All SN74AHC138QWBQBRQ1 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 SN74AHC138QWBQBRQ1 meets industry standards.
7.What is the process for return or replacement of SN74AHC138QWBQBRQ1?
All SN74AHC138QWBQBRQ1 units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHC138QWBQBRQ1, 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 SN74AHC138QWBQBRQ1 part is unused and in its original packaging.
Return procedure for SN74AHC138QWBQBRQ1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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