Texas Instruments 74CBT3305CDGKRG4

Overview

74CBT3305CDGKRG4 from Texas Instruments is a dual 1-bit FET bus switch IC designed for high-speed bidirectional signal gating in 5-V digital systems. It features 3 Ω typical ON-state resistance, –2-V undershoot protection on A/B ports, I_off partial-power-down support, 5 pF typical OFF-state I/O capacitance, and operates across 4 V to 5.5 V supply range - enabling low-distortion USB interface isolation and level-translating bus switching.

For engineers reviewing the 74CBT3305CDGKRG4 datasheet, 74CBT3305CDGKRG4 pinout, 74CBT3305CDGKRG4 application, or 74CBT3305CDGKRG4 equivalent, this device is selected for its TTL/CMOS-compatible control inputs, near-zero propagation delay (0.15 ns typ), robust OFF-state isolation under undershoot, and compatibility with 0- to 5-V signaling levels including 1.8 V, 2.5 V, and 3.3 V logic domains.

Technical Context

The 74CBT3305CDGKRG4 implements two independent FET-based transmission gates, each controlled by dedicated OE inputs (1OE, 2OE), supporting configurable 1-bit or combined 2-bit bus switching. Its active undershoot-protection circuitry monitors A/B port voltages and forces switch disable when transient undershoot reaches –2 V, preventing false turn-on during signal integrity events.

It uses I_off current limiting to block backflow during partial power-down, ensuring system-level isolation when V_CC = 0 V. The device exhibits rail-to-rail data I/O voltage tolerance (0–5.5 V), 3 µA max ICC, and maintains high-impedance state during power sequencing when OE is pulled low via external resistor.

Key Specifications

Pinout & Package

VSSOP-8 (DGK) package: 3.0 mm × 3.0 mm body, 0.65 mm pitch, exposed pad optional, RoHS-compliant Green (no Sb/Br) finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTD3305PW and 74LVC1G3157GW, the 74CBT3305CDGKRG4 uniquely combines dual independent switching, –2-V undershoot hardening, 3 Ω r_on, and 4–5.5 V operation - making it the only option qualified for robust 5-V USB isolation and mixed-voltage bus gating where signal integrity under transient stress is critical.

Availability

74CBT3305CDGKRG4 is available at Aetrix Electronics and suitable for USB interface isolation, low-voltage logic bridging, PCI slot power sequencing, and JTAG signal gating requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant Green packaging.

Supply support for 74CBT3305CDGKRG4 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.

The 74CBT3305CDGKRG4 belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered specifically for high-speed, low-distortion digital signal routing in 5-V systems where undershoot resilience and power-domain isolation are essential design requirements.

FAQ

What is the maximum undershoot voltage the 74CBT3305CDGKRG4 can withstand on its A/B ports?

The 74CBT3305CDGKRG4 provides active undershoot protection up to –2 V on both A and B ports, verified per datasheet test conditions (V_CC = 5.5 V, switch OFF). This means the device will remain reliably disabled even if transient negative spikes reach –2 V, preventing unintended conduction that could corrupt data or damage downstream circuitry. The protection is implemented via internal sensing circuitry, not passive clamping alone.

Does the 74CBT3305CDGKRG4 support partial-power-down operation, and how is it implemented?

Yes, the 74CBT3305CDGKRG4 supports partial-power-down via its I_off feature, which limits current to 10 µA max when V_CC = 0 V and I/O voltages range from 0 to 5.5 V. This is achieved through internal FET gate control that blocks reverse current flow between powered and unpowered domains. For reliable operation, OE pins must be tied to GND during power-off to ensure high-impedance isolation - confirmed in TI's SCDS125B datasheet Section 7.3.

What is the typical ON-state resistance of the 74CBT3305CDGKRG4, and how does it affect signal integrity?

The 74CBT3305CDGKRG4 has a typical ON-state resistance (r_on) of 3 Ω at V_CC = 4.5 V and I_O = 30 mA. At 50 mA, the resulting voltage drop is under 150 mV - negligible for 3.3-V or 5-V logic swings. This low r_on minimizes insertion loss and preserves edge rates, especially critical in high-speed USB or memory bus applications where signal degradation must stay below 5% of V_OH/V_OL thresholds.

Can the 74CBT3305CDGKRG4 be used to translate between different logic voltage levels, such as 1.8 V and 3.3 V?

Yes, the 74CBT3305CDGKRG4 supports true 0–5.5 V data I/O voltage range independent of V_CC, enabling bidirectional level translation between 1.8 V, 2.5 V, 3.3 V, and 5 V logic domains without external components. Its control inputs accept TTL/5-V CMOS thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V), so a 3.3-V microcontroller can directly drive OE while passing 1.8-V signals across the switch - validated in TI's SCDS125B Electrical Characteristics Table.

What package type and footprint does the 74CBT3305CDGKRG4 use, and is it RoHS-compliant?

The 74CBT3305CDGKRG4 uses the VSSOP-8 (DGK) package: 3.0 mm × 3.0 mm body, 0.65 mm lead pitch, with Green (RoHS & no Sb/Br) finish per TI's packaging addendum. It is fully RoHS-compliant and moisture-sensitive level 1 (unlimited floor life at ≤30°C/60% RH). The DGK drawing conforms to JEDEC MO-153, and thermal impedance θ_JA is 179°C/W - critical for thermal-aware layout in compact industrial modules.