SN74CB3Q3345PW

Overview

The SN74CB3Q3345PW is an automotive-grade, 8-bit FET bus switch from Texas Instruments' SN74CB3Q series. It operates on a single supply voltage ranging from 2.3 V to 3.6 V and features 5-V tolerant I/O ports that support rail-to-rail switching for various logic levels including 0.8 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V, and 5 V. The device utilizes a charge pump to maintain low and flat on-resistance (r_on) across the entire voltage range. Key electrical parameters include a typical r_on of 4 Ω, maximum input/output continuous current of ±128 mA, and typical off-state capacitance of 4 pF. It offers high bandwidth up to 500 MHz with propagation delay between 0.12 ns and 0.2 ns. ESD protection meets JESD 22 standards with 2000 V HBM and 1000 V CDM ratings.

Feature Summary

• Integrated charge pump mechanism ensures low and flat on-resistance for efficient signal transmission across wide voltage ranges.
• Supports partial power-down mode via I_off circuitry to prevent current backflow during device power-off states.
• Provides robust electrostatic discharge protection compliant with JESD 22 standards for human body and charged device models.
• Features 5-V tolerant inputs and outputs allowing direct interfacing with diverse voltage domains without level shifting.

Applications

• High-speed data buses in automotive infotainment and instrument cluster systems
• Voltage translation between different logic domains in network communication interfaces
• Data-intensive computing systems requiring low signal distortion and high bandwidth
• Broadband communication equipment utilizing rail-to-rail switching capabilities

Procurement Notes

Verify the specific suffix 'PW' corresponds to the TSSOP-20 package configuration required for your PCB layout. Confirm that the SN74CB3Q prefix indicates automotive qualification if your application demands AEC-Q100 compliance or extended reliability standards beyond standard industrial grades. Ensure design compatibility with the specified 2.3 V to 3.6 V supply range and check for any recent product change notifications affecting pinout or electrical characteristics.

Selection Notes

Select this component when designing systems that require bidirectional data transfer between mixed-voltage domains within automotive or high-performance computing environments. The SN74CB3Q3345 is suitable for applications demanding minimal propagation delay and low capacitive loading to preserve signal integrity at high frequencies. Consider its 5-V tolerance feature if interfacing directly with legacy 5-V logic devices while operating the control logic at lower voltages like 3.3 V or 2.5 V.

Part Context

This part belongs to the SN74CB3Q family of automotive-grade bus switches designed by Texas Instruments. The Q-series designation signifies qualification for automotive applications, offering enhanced reliability compared to standard commercial variants. It shares functional similarities with the non-automotive SN74CB3T3245 but includes specific ruggedization features. The device integrates eight independent switches into a single package, optimizing board space for complex multi-line data buses.

Replacement Considerations

SN74CB3T3245PW: Commercial grade equivalent with similar electrical performance but lacking automotive qualification.

FAQ

How does the SN74CB3Q3345 handle partial power-down scenarios?

The device includes an I_off circuit that automatically places the I/O ports in a high-impedance state when V_CC is removed or below the threshold, preventing current backflow from powered I/O lines into the unpowered supply rail.

What is the maximum switching frequency supported by the control inputs?

The OE and /OE control inputs support a maximum switching frequency of 20 MHz, allowing for rapid toggling of the bus switch state.

Does the on-resistance vary significantly with supply voltage?

No, the integrated charge pump maintains a low and flat on-resistance (typical 4 Ω) regardless of whether the supply voltage is at the minimum (2.3 V) or maximum (3.6 V) operating limits.