Texas Instruments CAHCT126QWBQARQ1

Overview

CAHCT126QWBQARQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive-qualified quadruple bus buffer gate with independent 3-state outputs, operating at 4.5V–5.5V supply, delivering ±8mA drive strength at 5V, TTL-compatible inputs, and designed for signal enable/disable in engine control units, body electronics, and ADAS domain controllers.

For engineers reviewing the CAHCT126QWBQARQ1 datasheet, CAHCT126QWBQARQ1 pinout, CAHCT126QWBQARQ1 application, or CAHCT126QWBQARQ1 equivalent, key selection criteria include its wettable-flank WQFN-14 package, -40°C to +125°C operation, 3-state output timing (tPLZ/tPHZ ≤ 8 ns @ 50 pF), latch-up immunity (>250 mA), and HBM/CDM ESD ratings per AEC-Q100.

Technical Context

This device implements four independent CMOS buffer channels, each with a dedicated output-enable (OE) input controlling high-impedance (Z) or pass-through (A→Y) functionality. Its balanced push-pull output stage supports symmetrical sourcing/sinking up to ±8 mA at VCC = 5 V, enabling robust driving of light capacitive loads (≤50 pF) without external termination.

The TTL-compatible input threshold (VIH = 2 V min, VIL = 0.8 V max) ensures interoperability with legacy 5-V logic families, while internal clamp diodes (±20 mA IK/OK) and pulldown-recommended OE pins ensure safe power-up/power-down sequencing in automotive environments.

Key Specifications

Pinout & Package

CAHCT126QWBQARQ1 uses a 3 mm × 2.5 mm wettable-flank WQFN-14 (BQA) package with exposed thermal pad. The wettable flanks support automated optical inspection (AOI) of solder fillets, critical for automotive manufacturing traceability.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bus buffer applications.

Compared with SN74AHCT125QDRQ1 and SN74LVC126AQPWRQ1, CAHCT126QWBQARQ1 uniquely combines per-channel 3-state control, wettable-flank WQFN packaging, and full AEC-Q100 Grade 1 qualification-making it the only option certified for high-reliability, space-constrained, multi-function automotive signal routing.

Availability

CAHCT126QWBQARQ1 is available at Aetrix Electronics and suitable for engine control units, body control modules, and ADAS camera interfaces requiring stable component supply across extended temperature ranges and automotive production lifecycles.

Supply support for CAHCT126QWBQARQ1 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 decades of automotive qualification experience and ISO/TS 16949-certified manufacturing.

CAHCT126QWBQARQ1 belongs to TI's automotive-qualified AHCT logic family, engineered specifically for robust signal buffering, level translation, and bus isolation in harsh-temperature vehicle subsystems.

FAQ

What is the maximum capacitive load supported by CAHCT126QWBQARQ1 while maintaining specified timing?

CAHCT126QWBQARQ1 is characterized for loads up to 50 pF in switching specifications (tPLH, tPHL, tPZH, etc.). While larger loads may function, propagation delays increase nonlinearly beyond this point-e.g., tPLH rises from 6.5 ns (15 pF) to 8.5 ns (50 pF). For designs targeting strict setup/hold margins in high-speed control loops, staying at or below 50 pF ensures compliance with published timing windows.

How should unused inputs be handled on CAHCT126QWBQARQ1?

All unused inputs on CAHCT126QWBQARQ1 must be terminated to either VCC or GND-never left floating-to prevent oscillation, excessive current draw, or undefined logic states. TI recommends 10-kΩ pull-up or pull-down resistors for inputs that may be inactive during certain modes. Direct connection is acceptable for permanently unused pins, as confirmed in Section 5.3 and Figure 8-3 of the datasheet.

Does CAHCT126QWBQARQ1 require external pull-down resistors on OE pins?

Yes-TI explicitly recommends tying each OE pin to GND through a pulldown resistor to ensure high-impedance outputs during power-up and power-down sequences. The minimum resistor value depends on the current-sourcing capability of the driving source; typical values range from 4.7 kΩ to 10 kΩ. This prevents unintended signal assertion before MCU initialization completes.

Is the thermal pad on CAHCT126QWBQARQ1 required to be connected to ground?

No-the thermal pad on CAHCT126QWBQARQ1 may be connected to GND or left electrically floating, per Table 4-1 and Section 7.3.4. Connecting it to GND improves thermal dissipation and reduces EMI, but floating is acceptable if PCB layout constraints prohibit grounding. It must never be connected to any signal or supply voltage other than GND.

What is the significance of "wettable flanks" in the CAHCT126QWBQARQ1 BQA package?

Wettable flanks on the CAHCT126QWBQARQ1's BQA package provide enhanced side-wall solder fillets during reflow, enabling reliable automated optical inspection (AOI) of solder joints-a mandatory requirement for automotive Tier 1 suppliers. This feature directly supports zero-defect manufacturing goals and IPC-A-610 Class 3 compliance without requiring X-ray inspection.