8.1 Overview

The SN74CB3T3306 device is organized as two 1-bit bus switches with separate ouput-enable (1OE, 2OE) inputs. It can be used as two 1-bit bus switches or as one 2-bit bus switch. When OE is low, the associated 1-bit bus switch is ON, and the A port is connected to the B port, allowing bidirectional data flow between ports. When OE is high, the associated 1-bit bus switch is OFF, and a high-impedance state exists between the A and B ports.

This device is fully specified for partial-power-down applications using I_off. The I_off feature ensures that damaging current will not backflow through the device when it is powered down. The SN74CB3T3306 device has isolation during power off.

To ensure the high-impedance state during power up or power down, OE should be tied to V_CC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

Figure 5. Typical DC Voltage-Translation Characteristics

8.2 Functional Block Diagrams

Figure 6. Functional Block Diagram, SN74CB3T3306

Figure 7. Simplified Schematic, Each FET Switch (SW)

8.3 Feature Description

The SN74CB3T3306 is ideal for low-power portable equipment. Power consumption is low by design, I_CC =
20 μA, On-state resistance is low (r_on = 5 Ω) It has bidirectional data flow with near zero propagation delay. The devices minimizes loading due to the low input/output capacitance C_io(OFF) = 4.5 pF Typ. Operating V_CC range from 2.3 V to 3.6 V. The output tracks V_CC.Data and control inputs provide undershoot clamp diodes. Control inputs can be driven by TTL or 5-V/3.3-V CMOS outputs. It supports mixed-mode signal operation on all data I/O ports. Data I/Os support 0- to 5-V signaling levels (0.8 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V, 5 V). The device is protected from damaging current, I_off supports partial shutdown which prevents the current from flowing back through the device when it is powered down. In addition, it has 5-V tolerant I/Os with device powered up or powered down. The device is latch-up resistant with 250 mA exceeding the JESD 17 standard, providing protection from destruction due to latch-up. This device is protected against electrostatic discharge. It is tested per JESD 22 using 2000-V Human-Body Model (A114-B, Class II), and 1000-V Charged-Device Model (C101).

8.4 Device Functional Modes

Table 1 lists the functional modes for the SN74CB3T3306.