Texas Instruments CAHCT1G126QDCKRQ1

Overview

CAHCT1G126QDCKRQ1 from Texas Instruments is an automotive-qualified single bus buffer gate with 3-state output, operating from 3 V to 5.5 V supply, delivering ≤6 ns propagation delay at 5 V, ±8-mA output drive, and <10 µA quiescent current - used for signal enable/disable in vehicle body control modules and infotainment data routing.

For engineers reviewing the CAHCT1G126QDCKRQ1 datasheet, CAHCT1G126QDCKRQ1 pinout, CAHCT1G126QDCKRQ1 application, or CAHCT1G126QDCKRQ1 equivalent, key selection criteria include AEC-Q100 qualification, SOT-SC70-5 package thermal resistance (293.4 °C/W), TTL-compatible inputs, and 3-state output control timing under 50-pF load.

Technical Context

This device implements a positive-logic non-inverting buffer with active-high output-enable (OE) control. When OE is high, input A passes directly to output Y; when OE is low, Y enters high-impedance state - enabling bidirectional bus sharing and signal isolation in mixed-voltage automotive subsystems.

It supports dual-supply operation across 3 V–5.5 V, maintains TTL-level input thresholds (VIH = 2 V min at 4.5–5.5 V), and guarantees VOL ≤ 0.52 V at 8-mA sink and VOH ≥ 3.66 V at 8-mA source under 5-V conditions - ensuring robust noise margins in noisy automotive environments.

Key Specifications

Pinout & Package

CAHCT1G126QDCKRQ1 uses the SC-70 (DCK) 5-pin surface-mount package (2.0 mm × 2.1 mm body, 1.25 mm width), optimized for space-constrained automotive PCBs and compatible with standard reflow profiles (MSL Level-1, 260 °C peak).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC1G126QDCKRQ1 and MC74VHC1G126DTT1G, CAHCT1G126QDCKRQ1 provides tighter propagation delay control, guaranteed TTL input compatibility at 5 V, and full AEC-Q100 Grade 1 test reporting - making it the preferred choice for safety-critical signal gating where timing predictability and automotive traceability are mandatory.

Availability

CAHCT1G126QDCKRQ1 is available at Aetrix Electronics and suitable for automotive body electronics, instrument cluster interfaces, ADAS sensor multiplexing, and infotainment mute control requiring stable component supply across extended product lifecycles.

Supply support for CAHCT1G126QDCKRQ1 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 ICs, with decades of automotive qualification expertise and broad AEC-Q100 portfolio coverage.

CAHCT1G126QDCKRQ1 belongs to TI's SN74AHCT automotive logic family, designed specifically for robust signal buffering and bus control in harsh-temperature, high-reliability vehicle subsystems - emphasizing low power, fast switching, and fault-tolerant I/O behavior.

FAQ

What is the maximum capacitive load supported by CAHCT1G126QDCKRQ1 while maintaining full datasheet timing specifications?

CAHCT1G126QDCKRQ1 guarantees all switching characteristics (tPLH, tPHL, tPZH, etc.) up to 50 pF load capacitance at both 3 V and 5 V supply. Beyond 50 pF, propagation delays increase nonlinearly - e.g., tPLH rises from 5.5 ns (15 pF) to 10.5 ns (50 pF) at 5 V - and output voltage margins may degrade. For loads >50 pF, derating analysis or simulation with IBIS model is recommended before final design sign-off.

Does CAHCT1G126QDCKRQ1 require external pull-up or pull-down resistors on the OE pin for safe power-up behavior?

Yes - to ensure the output remains in high-impedance state during power-up and prevent bus contention, OE must be held low until VCC stabilizes. TI recommends tying OE to GND through a pulldown resistor; 10 kΩ is typical, balancing leakage current (<1 µA) against noise immunity. CAHCT1G126QDCKRQ1 has no internal OE pull-down, so external biasing is mandatory in all automotive implementations.

Can CAHCT1G126QDCKRQ1 interface directly with 3.3-V microcontrollers while powered from a 5-V rail?

No - CAHCT1G126QDCKRQ1 powered at 5 V has VIH(min) = 2.0 V, which is compatible with 3.3-V logic HIGH, but its outputs swing rail-to-rail (0 V to 5 V). Direct connection to a 3.3-V MCU input risks overvoltage damage unless the MCU input is 5-V tolerant. For mixed-voltage interfacing, use a level translator or select CAHCT1G126QDCKRQ1 only in 3.3-V systems (where VCC = 3.3 V yields VIH = 1.4 V, matching 3.3-V logic).

What is the thermal resistance (RθJA) of CAHCT1G126QDCKRQ1 in its SC-70 package, and how does it impact continuous operation at 125 °C ambient?

CAHCT1G126QDCKRQ1 in the DCK (SC-70) package has RθJA = 293.4 °C/W. At 125 °C ambient and worst-case ICC = 10 µA plus 8-mA output current, total power dissipation is ~40 mW, resulting in junction temperature rise of ~11.7 °C - well below the 150 °C absolute max. This confirms safe continuous operation in under-hood applications without heatsinking or airflow.

Is CAHCT1G126QDCKRQ1 pin-compatible with non-automotive versions like SN74AHCT1G126DBVR?

Yes - CAHCT1G126QDCKRQ1 shares identical pinout, electrical behavior, and functional truth table with SN74AHCT1G126DBVR and SN74AHCT1G126DCKR. The only differences are AEC-Q100 qualification, enhanced screening, and automotive-grade traceability; no PCB redesign is needed when upgrading from commercial to automotive grade in the same DCK package.