Texas Instruments SN74HCS245QPWRQ1

Overview

SN74HCS245QPWRQ1 from Texas Instruments is an AEC-Q100 Grade 1 qualified octal bus transceiver with 3-state outputs and Schmitt-trigger inputs, operating from 2 V to 6 V. It features ±7.8-mA output drive at 6 V, 100 nA typical supply current, and hysteresis (ΔVT) up to 1.6 V for noise immunity-used in automotive body control modules to isolate and condition bidirectional data buses between microcontrollers and peripheral sensors.

For engineers reviewing the SN74HCS245QPWRQ1 datasheet, SN74HCS245QPWRQ1 pinout, SN74HCS245QPWRQ1 application, or SN74HCS245QPWRQ1 equivalent, key selection criteria include automotive temperature range (–40°C to +125°C), Schmitt-trigger input hysteresis, 3-state bus isolation timing (tpd ≤ 13 ns at 6 V), and wettable-flank VQFN-20 package compatibility with AOI inspection.

Technical Context

The SN74HCS245QPWRQ1 implements eight independent bidirectional CMOS transceivers controlled by a shared DIR pin (L = B→A, H = A→B) and OE pin (active-low). All outputs enter high-impedance state when OE is high, enabling bus arbitration without contention.

Schmitt-trigger inputs provide defined VT+ (up to 4.2 V at 6 V) and VT− (as low as 1.2 V at 6 V), delivering ≥0.6 V hysteresis to reject slow-edge or noisy signals-critical for switch debouncing and long-trace signal conditioning in harsh automotive environments.

Key Specifications

Pinout & Package

SN74HCS245QPWRQ1 is packaged in a 20-pin wettable-flank VQFN (WRKS) with 4.50 mm × 2.50 mm body size and exposed thermal pad (connected to GND or left floating). The package supports automated optical inspection (AOI) via side-fillet solder joints.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal transceiver applications.

Compared with SN74HCS245PWRQ1 and MC74HC245ADTR2G, the SN74HCS245QPWRQ1 uniquely combines AEC-Q100 Grade 1 qualification, wettable-flank packaging for zero-defect manufacturing, and guaranteed Schmitt hysteresis across full temperature range-making it the only choice for new automotive designs requiring production traceability and field reliability.

Availability

SN74HCS245QPWRQ1 is available at Aetrix Electronics and suitable for automotive body control modules, door module switch interfaces, instrument cluster displays, and telematics gateway signal conditioning requiring stable component supply across extended temperature and high-reliability manufacturing.

Supply support for SN74HCS245QPWRQ1 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 90 years of innovation in power management and signal chain technologies.

The SN74HCS245QPWRQ1 belongs to TI's automotive-qualified HCS logic family, designed specifically for noise-immune, low-power bidirectional bus interfacing in electric powertrain, chassis, and body electronics systems.

FAQ

What is the maximum capacitive load SN74HCS245QPWRQ1 can drive while meeting datasheet timing specs?

The SN74HCS245QPWRQ1 is characterized for CL = 50 pF in switching specifications. Driving loads >50 pF increases propagation delay and transition time beyond guaranteed limits-e.g., tpd rises from 13 ns (typical at 6 V, 50 pF) to >25 ns at 100 pF. For reliable timing compliance in automotive applications, keep total load capacitance ≤50 pF using short traces and minimal stubs. The SN74HCS245QPWRQ1 datasheet explicitly states this limit in Section 9.2.1.1.

How should unused channels of SN74HCS245QPWRQ1 be terminated in an automotive design?

Unused transceiver channels of SN74HCS245QPWRQ1 must be terminated to VCC or GND via 100-kΩ resistors-per TI's Figure 8-2 and Section 8.3.1. Direct connection risks latch-up or excessive leakage in temperature extremes. Leaving inputs floating violates AEC-Q100 reliability requirements and may cause erratic behavior due to noise coupling. The SN74HCS245QPWRQ1's Schmitt-trigger inputs do not reduce leakage when floating; termination ensures deterministic logic states and ESD robustness.

Does SN74HCS245QPWRQ1 support hot insertion or live bus swapping?

SN74HCS245QPWRQ1 supports controlled hot insertion only when OE is held high (all outputs in high-Z) during power-up. Its absolute maximum ratings include VI = –0.5 V to VCC + 0.5 V and clamp diodes rated for ±20 mA-allowing limited transient overvoltage during plug-in. However, TI does not guarantee hot-swap functionality. For robust live-swapping, external protection (e.g., series resistors, TVS diodes) is required. The SN74HCS245QPWRQ1 datasheet cautions against violating Absolute Maximum Ratings during such events.

What is the purpose of the thermal pad on the SN74HCS245QPWRQ1 WRKS package?

The exposed thermal pad on the SN74HCS245QPWRQ1 WRKS package serves dual purposes: thermal dissipation (RθJB = 49.6°C/W) and mechanical anchoring. TI specifies it may be connected to GND or left floating-but grounding improves heat transfer to the PCB plane and reduces junction temperature by up to 15°C under 7.8-mA continuous drive. It must never connect to VCC or signal nets. The SN74HCS245QPWRQ1 mechanical drawings define pad dimensions and solder stencil recommendations for optimal reflow yield.

Can SN74HCS245QPWRQ1 be used to replace SN74HC245 in existing automotive designs?

SN74HCS245QPWRQ1 is not a direct drop-in replacement for SN74HC245 due to key differences: it features Schmitt-trigger inputs (vs. standard CMOS), AEC-Q100 qualification, and wettable-flank packaging. While pinout and logic function match, the hysteresis alters input threshold behavior-requiring validation of edge timing and noise margins. The SN74HCS245QPWRQ1 also has lower ICC (100 nA vs. ~4 µA) and tighter ESD specs. Migration requires full requalification per automotive change-control processes.