Texas Instruments SN74CBT6800CDBQR

Overview

SN74CBT6800CDBQR from Texas Instruments is a 10-bit bidirectional FET bus switch with near-zero propagation delay (0.15 ns typical at 5 V), 3 Ω typical ON-state resistance, and active undershoot protection up to −2 V on both A and B ports. It supports live insertion in PCI hot-plug systems via B-port precharge to user-defined BIASV and operates across 4 V–5.5 V VCC with 0–5 V data I/O signaling.

For engineers reviewing the SN74CBT6800CDBQR datasheet, SN74CBT6800CDBQR pinout, SN74CBT6800CDBQR application, or SN74CBT6800CDBQR equivalent, key selection criteria include hot-plug noise suppression capability, Ioff partial-power-down compliance, low 5.5 pF OFF-state I/O capacitance, and TSSOP-24 package compatibility with high-density PCB layouts.

Technical Context

This device implements a TTL-compatible 10-bit analog/digital bus switch using integrated FETs with undervoltage-sensing undershoot-protection circuitry on both A and B ports. Its internal enable logic drives 10 independent transmission gates controlled by a single ON input, with bias voltage (BIASV) applied externally to precharge B-port nodes during isolation.

The architecture supports true bidirectional signal flow with no direction pin, achieves sub-nanosecond propagation delay via low-ron FET design, and guarantees isolation during power sequencing through Ioff current limiting (<10 µA at VCC = 0 V) and clamp diode protection on all data/control pins.

Key Specifications

Pinout & Package

TSSOP-24 package (PW), 7.9 mm × 4.5 mm footprint, 1.2 mm max height, 0.65 mm lead pitch, RoHS-compliant NIPDAU finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT6800CDBQR, SN74CBTD6800CDBQR adds bus-hold functionality at the cost of higher quiescent current, while SN74CB3Q3244PWR offers lower-voltage operation but omits critical hot-plug features-making SN74CBT6800CDBQR the only option supporting −2 V undershoot protection and BIASV-controlled live-insertion noise suppression in 5-V PCI environments.

Availability

SN74CBT6800CDBQR is available at Aetrix Electronics and suitable for PCI hot-plug interface design, memory interleaving bus isolation, and low-distortion analog signal gating requiring stable component supply and long-term manufacturability.

Supply support for SN74CBT6800CDBQR 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 digital signal technologies with over 50 years of innovation in high-reliability interface solutions.

The SN74CBT6800CDBQR belongs to TI's Widebus™ family of high-speed bus switches, engineered specifically for hot-plug-capable computing and communications infrastructure requiring robust signal integrity and power sequencing resilience.

FAQ

What is the maximum undershoot voltage the SN74CBT6800CDBQR can withstand on its A and B ports?

The SN74CBT6800CDBQR provides active undershoot protection up to −2 V on both A and B ports, as confirmed in the absolute maximum ratings and functional description. This protection operates by sensing undershoot events and forcing the internal switch into the OFF state to prevent unintended conduction. The −2 V rating is specified under test conditions with II ≥ −50 mA and applies across the full operating temperature range of −40°C to 85°C.

How does the BIASV pin function in the SN74CBT6800CDBQR during hot-plug operations?

The BIASV pin on the SN74CBT6800CDBQR supplies an external bias voltage (0 V to VCC) that precharges the B-port terminals through an internal ~10-kΩ equivalent resistor when the device is disabled (ON = H) or powered down (VCC = 0 V). This precharge holds B1–B10 at a stable voltage aligned with downstream receiver input thresholds, preventing live-insertion glitches from crossing the logic threshold region during card mating. The feature is explicitly validated for PCI hot-plug compliance.

Does the SN74CBT6800CDBQR support partial-power-down mode, and how is it implemented?

Yes, the SN74CBT6800CDBQR fully supports partial-power-down mode via its Ioff specification. When VCC = 0 V, the device limits leakage current to ≤10 µA regardless of voltage applied to A/B ports or BIASV, preventing damaging backflow current into unpowered sections of the system. This behavior is guaranteed per JESD 78 Class II latch-up testing and is enabled by internal circuitry that disables gate drive to all FETs while maintaining ESD protection diode integrity.

What is the typical ON-state resistance (ron) of the SN74CBT6800CDBQR, and how does it affect signal integrity?

The SN74CBT6800CDBQR has a typical ON-state resistance (ron) of 3 Ω at VCC = 4.5 V and IO = 30 mA, with a maximum of 6 Ω across operating conditions. This low ron minimizes voltage drop across the switch, preserving signal amplitude and reducing insertion loss-critical for maintaining noise margins in high-speed digital and analog signal paths. Measured as the voltage drop between A and B terminals at specified current, ron remains stable across the 0–5 V I/O range, ensuring consistent performance with mixed-voltage signaling.

Can the SN74CBT6800CDBQR be used in analog signal routing applications, and what parameters support this use case?

Yes, the SN74CBT6800CDBQR is qualified for analog signal routing due to its low 5.5 pF OFF-state I/O capacitance (Cio(OFF)), flat ron vs. voltage characteristic, and absence of significant charge injection. Its 0–5 V data I/O tolerance, sub-nanosecond propagation delay, and bidirectional transparency allow clean passage of DC-coupled analog signals up to ~100 MHz. The device is explicitly cited in the datasheet for "analog applications" and supports low-distortion gating in sensor interfaces and mixed-signal systems.