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Texas Instruments CAHCT138QWBQBRQ1
- Part No.:
- CAHCT138QWBQBRQ1
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
CAHCT138QWBQBRQ1.pdf
- Description:
- AUTOMOTIVE CATALOG 3-LINE TO 8-L
- Quantity:
- Payment:
- Shipping:
Inventory:3,443
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Product details
Overview
CAHCT138QWBQBRQ1 from Texas Instruments is an automotive-grade 3-line to 8-line decoder/demultiplexer in a 16-pin WQFN (BQB) package, operating from 4.5 V to 5.5 V, with propagation delays as low as 6.6 ns (G1→Y), TTL-compatible inputs, and latch-up immunity exceeding 250 mA per JESD17 - deployed in high-speed memory decoding and data-routing subsystems of ADAS control units.
For engineers reviewing the CAHCT138QWBQBRQ1 datasheet, CAHCT138QWBQBRQ1 pinout, CAHCT138QWBQBRQ1 application, or CAHCT138QWBQBRQ1 equivalent, key selection criteria include automotive AEC-Q100 qualification, 125°C max operating temperature, WQFN thermal pad handling, enable-input cascading architecture, and output drive capability of ±8 mA at 5 V.
Technical Context
This device implements positive-logic binary decoding using three select inputs (A, B, C) and three enable terminals (G1 active-high; G2A/G2B active-low), enabling precise selection of one of eight active-low outputs (Y0–Y7). Its EPIC CMOS process ensures TTL-level input compatibility while maintaining CMOS power efficiency.
Functional modes are fully defined by the truth table: all outputs remain high when any enable condition fails; only one output goes low when G1 = H and G2A = G2B = L and a unique 3-bit select code is applied. The enable structure supports direct cascading for 24-line decoding without external inverters and permits use of G1 as a data line in demultiplexing configurations.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard 5 V automotive logic rails and tolerant of transient droop. |
| Propagation Delay (G1→Y) | 6.6 ns (min) / 10.5 ns (max) at 5 V, CL = 15 pF - enables sub-10 ns system-level address decode timing. |
| Output Drive | ±8 mA at VOH/VOL - sufficient to directly drive multiple 74AHCT inputs or small LED indicators without buffering. |
| Input Compatibility | TTL-voltage thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V) - interoperable with legacy 5 V TTL and LVTTL sources. |
| Operating Temperature | −40 °C to +125 °C - qualified per AEC-Q100 Grade 1 for under-hood and powertrain ECUs. |
| ESD Rating | ±2000 V HBM - meets automotive ESD robustness requirements per AEC-Q100-002. |
| Latch-Up Immunity | >250 mA per JESD17 - prevents destructive latch-up during voltage transients in noisy vehicle environments. |
Pinout & Package
CAHCT138QWBQBRQ1 uses a 16-pin WQFN package (BQB) with 3.5 mm × 2.5 mm body size, 0.5 mm pitch, and exposed thermal pad. The pad must be soldered to PCB ground plane for optimal thermal performance and mechanical reliability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A (Pin 1) | Select input A (LSB) | Binary address bit 0; sampled synchronously with enable conditions to determine output activation. |
| B (Pin 2) | Select input B | Binary address bit 1; combined with A and C to generate 3-bit decode word. |
| C (Pin 3) | Select input C (MSB) | Binary address bit 2; completes 3-bit selection for full 8-output mapping. |
| G2A (Pin 4) | Active-low enable A | First cascade enable; must be low with G2B for decoder activation - simplifies hierarchical decoding. |
| G2B (Pin 5) | Active-low enable B | Second cascade enable; used with G2A to reduce external gating in multi-chip decode trees. |
| G1 (Pin 6) | Active-high enable | Primary enable; doubles as data input in demux mode - enables 1-to-8 signal distribution. |
| GND (Pin 8) | Ground reference | Power return path; connects to PCB ground plane and thermal pad for noise suppression. |
| VCC (Pin 16) | Supply voltage | 5 V nominal rail; requires local 0.1 µF bypass capacitor placed within 2 mm of pin. |
| Y0–Y7 (Pins 7,9–15) | Active-low decoded outputs | Complementary outputs asserted low per select code; Y0 = LSB, Y7 = MSB - no pull-ups required for open-drain interfacing. |
| Thermal Pad | Exposed copper pad | Must be soldered to solid GND pour; improves θJA by ~30% vs. floating pad and enhances mechanical attachment. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q100 Qualified | Grade 1 (−40 °C to +125 °C) - certified for safety-critical automotive applications including engine control and braking systems. |
| Three Enable Inputs | G1 (active-high), G2A/G2B (active-low) - enables 24-line decoding without external inverters and supports flexible demux/data-gating topologies. |
| EPIC CMOS Process | Combines TTL input compatibility with CMOS power efficiency - eliminates level-shifter need while maintaining <40 µA ICC at 5.5 V. |
| High-Speed Propagation | tPLH/tPHL down to 6.6 ns (G1→Y) - reduces address decode latency below typical SRAM access time, minimizing system wait states. |
| Robust Input/Output Protection | ±2000 V HBM ESD, >250 mA latch-up immunity - sustains operation during load-dump and jump-start events in 12 V vehicle systems. |
Applications
| Automotive Memory Address Decoding | ADAS Sensor Data Routing |
|---|---|
Use Scenario: Selecting individual memory banks in a radar processor's dual-bank SRAM subsystem. IC Role / Device Role / Timing Role: 3-to-8 address decoder that asserts chip-select lines with sub-10 ns delay, synchronized to CPU address bus and memory enable signals. Use Value: Eliminates decode-induced wait states by ensuring decoder delay + memory enable time < memory access time (e.g., 25 ns). | Use Scenario: Distributing time-triggered CAN FD messages from a central gateway to eight camera modules. IC Role / Device Role / Timing Role: Demultiplexer using G1 as data input and A/B/C as channel ID - routes single serial stream to one of eight isolated output paths. Use Value: Enables deterministic, low-jitter routing without FPGA logic resources - critical for ISO 26262 ASIL-B timing compliance. |
| Engine Control Unit I/O Expansion | Infotainment System Peripheral Selection |
Use Scenario: Enabling discrete diagnostic LEDs and solenoid drivers across 8 cylinder control circuits. IC Role / Device Role / Timing Role: Output-enable controller where Y0–Y7 drive ULN2003A Darlington arrays - each output activated by unique 3-bit engine cycle phase code. Use Value: Reduces MCU GPIO count by 8 pins while maintaining real-time response (<12 ns propagation) for misfire detection feedback. | Use Scenario: Selecting between HDMI, LVDS, and MIPI DSI display interfaces in a multi-screen head unit. IC Role / Device Role / Timing Role: Bus selector that gates clock/data lanes using active-low outputs tied to analog switch enable inputs (e.g., TS3USB221). Use Value: Provides glitch-free interface switching via synchronous enable sequencing - avoids video artifacts during source transitions. |
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 |
|---|---|---|---|
| SN74AHCT138QPWRQ1 | TSSOP-16 package (5.0 × 6.4 mm); RθJA = 135.9 °C/W vs. 105.6 °C/W for BQB; identical electrical specs. | Suitable for prototyping or space-tolerant layouts; less effective thermal dissipation in sealed enclosures. | Select when board reflow profile or test fixture constraints favor TSSOP over WQFN. |
| SN74LV138AQPWRQ1 | Lower VCC range (2.0–5.5 V); higher tPLH (11.5 ns min at 3.3 V); LV logic family - not TTL-compatible. | Used in mixed-voltage 3.3 V domains; incompatible with 5 V TTL inputs without level translation. | Choose only for 3.3 V systems requiring wider supply margin; avoid if interfacing legacy 5 V controllers. |
Compared with SN74AHCT138QPWRQ1 and SN74LV138AQPWRQ1, CAHCT138QWBQBRQ1 delivers superior thermal performance in compact automotive modules, maintains native TTL input compatibility for legacy integration, and provides the lowest propagation delay among AEC-Q100-qualified 3-to-8 decoders in production.
Availability
CAHCT138QWBQBRQ1 is available at Aetrix Electronics and suitable for automotive ADAS control units, engine management systems, and infotainment head units requiring stable component supply across extended product lifecycles.
Supply support for CAHCT138QWBQBRQ1 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 ICs, with decades of automotive qualification expertise and AEC-Q100-compliant manufacturing.
CAHCT138QWBQBRQ1 belongs to TI's automotive logic portfolio, engineered specifically for high-reliability, high-speed decoding in safety-critical vehicle subsystems - emphasizing thermal resilience, ESD robustness, and seamless integration with 5 V microcontrollers and memory interfaces.
FAQ
What is the maximum operating temperature for CAHCT138QWBQBRQ1?
The CAHCT138QWBQBRQ1 is rated for continuous operation from −40 °C to +125 °C ambient temperature, meeting AEC-Q100 Grade 1 requirements for under-hood automotive applications. This rating is validated across the full 4.5 V to 5.5 V supply range and confirmed in TI's SGDS022B datasheet Section 4.3.
Does CAHCT138QWBQBRQ1 require external pull-up resistors on its Y0–Y7 outputs?
No, CAHCT138QWBQBRQ1 outputs are push-pull and actively drive both high and low states. Its Y0–Y7 outputs assert low when selected and high when deselected - no external pull-ups are needed. However, if interfacing with open-drain buses, external termination may be required per system-level signaling standards.
Can CAHCT138QWBQBRQ1 be used as a demultiplexer, and how is that configured?
Yes, CAHCT138QWBQBRQ1 functions as a 1-to-8 demultiplexer when G1 is used as the data input and A/B/C serve as the 3-bit channel select lines. With G2A and G2B held low, the data present at G1 appears inverted on the selected Yx output - enabling clean signal distribution in time-triggered automotive networks.
What is the recommended PCB layout practice for the thermal pad on CAHCT138QWBQBRQ1?
The exposed thermal pad on CAHCT138QWBQBRQ1 must be soldered to a solid GND plane using a minimum of 8–12 thermal vias (0.3 mm diameter, spaced ≤1 mm apart) filled or tented per TI SLUA271 guidelines. The pad should not connect to any signal or supply net - only GND - to ensure optimal thermal dissipation and mechanical reliability.
Is CAHCT138QWBQBRQ1 pin-compatible with non-automotive versions like SN74AHCT138N?
No - CAHCT138QWBQBRQ1 uses a 16-pin WQFN (BQB) package, whereas SN74AHCT138N is a 16-pin PDIP. Even within WQFN variants, CAHCT138QWBQBRQ1 has different pin 1 marking (AT138Q) and thermal pad design rules versus commercial-grade AHCT138 variants. Always verify land pattern against TI's BQB0016B mechanical drawing.
CAHCT138QWBQBRQ1 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- 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:
- 4.5V ~ 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)
CAHCT138QWBQBRQ1 FAQ
1.How can I place an order for CAHCT138QWBQBRQ1 through Aetrix?
Please submit a Request for Quotation (RFQ) for CAHCT138QWBQBRQ1 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 CAHCT138QWBQBRQ1 reliable?
The price and inventory of CAHCT138QWBQBRQ1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CAHCT138QWBQBRQ1 is usually 5 days.
3.What payment methods are accepted for CAHCT138QWBQBRQ1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CAHCT138QWBQBRQ1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CAHCT138QWBQBRQ1?
CAHCT138QWBQBRQ1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CAHCT138QWBQBRQ1 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 CAHCT138QWBQBRQ1?
For technical support, including CAHCT138QWBQBRQ1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CAHCT138QWBQBRQ1 requirements.
6.How does Aetrix verify that CAHCT138QWBQBRQ1 is sourced from the original manufacturer or authorized distributors?
All CAHCT138QWBQBRQ1 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 CAHCT138QWBQBRQ1 meets industry standards.
7.What is the process for return or replacement of CAHCT138QWBQBRQ1?
All CAHCT138QWBQBRQ1 units undergo pre-shipment inspection (PSI). If there is an issue with CAHCT138QWBQBRQ1, 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 CAHCT138QWBQBRQ1 part is unused and in its original packaging.
Return procedure for CAHCT138QWBQBRQ1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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