SCDS143C October 2003 – June 2015 SN74CB3Q3125
The SN74CB3Q3125 device is a high-bandwidth FET bus switch utilizing a charge pump to elevate the gate voltage of the pass transistor, providing a low and flat ON-state resistance (ron). The low and flat ON-state resistance allows for minimal propagation delay and supports rail-to-rail switching on the data input/output (I/O) ports. The SN74CB3Q3125 device also features low data I/O capacitance to minimize capacitive loading and signal distortion on the data bus. Specifically designed to support high-bandwidth applications, the SN74CB3Q3125 device provides an optimized interface solution ideally suited for broadband communications, networking, and data-intensive computing systems.
The SN74CB3Q3125 device is organized as four 1-bit bus switches with separate output-enable (1OE, 2OE, 3OE, 4OE) inputs. It can be used as four 1-bit bus switches or as one 4-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 Ioff. The Ioff circuitry prevents damaging current backflow through the device when it is powered down. The device has isolation during power off.
To ensure the high-impedance state during power up or power down, OE should be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.
The SN74CB3Q3125 device has a high-bandwidth data path (up to 500 MHz) and has 5-V tolerant I/Os with the device powered up or powered down. It also has low and flat ON-state resistance (ron) characteristics over operating range (ron = 4-Ω Typ).
The SN74CB3Q3125 device has rail-to-rail switching on data I/O ports for 0-V to 5-V switching with
3.3-V VCCand 0-V to 3.3-V switching with 2.5-V VCC as well as bidirectional data flow with near-zero propagation delay and low input/output capacitance that minimizes loading and signal distortion (Cio(OFF) = 3.5-pF Typ).
The SN74CB3Q3125 device also provides a fast switching frequency (fOE = 20-MHz Max) with data and control inputs that provide undershoot clamp diodes as well as low power consumption (ICC = 0.6-mA Typ).
The VCC operating range is from 2.3 V to 3.6 V and the data I/Os support 0-V to 5-V signal levels of
(0.8 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V, 5 V).
The control inputs can be driven by TTL or 5-V or 3.3-V CMOS outputs, and Ioff supports partial-power-down mode operation.
Table 1 lists the functional modes for the SN74CB3Q3125 device.
|L||B||A port = B port|