The SN74CBT3257C is a high-speed TTL-compatible FET multiplexer/demultiplexer with low ON-state resistance (r_on), allowing for minimal propagation delay. Active Undershoot-Protection Circuitry on the A and B ports of the SN74CBT3257C provides protection for undershoot up to –2 V by sensing an undershoot event and ensuring that the switch remains in the proper OFF state.

The SN74CBT3257C is a 4-bit 1-of-2 multiplexer/demultiplexer with a single output-enable (OE\) input. The select (S) input controls the data path of the multiplexer/demultiplexer. When OE\ is low, the multiplexer/demultiplexer is enabled and the A port is connected to the B port, allowing bidirectional data flow between ports. When OE\ is high, the multiplexer/demultiplexer is disabled 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 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.

• Undershoot Protection for Off-Isolation on A and B Ports Up To .2 V
• Bidirectional Data Flow, With Near-Zero Propagation Delay
• Low ON-State Resistance (ron) Characteristics (ron = 3 Typical)
• Low Input/Output Capacitance Minimizes Loading and Signal Distortion (Cio(OFF) = 5.5 pF Typical)
• Data and Control Inputs Provide Undershoot Clamp Diodes
• Low Power Consumption (ICC = 3 μA Max)
• VCC Operating Range From 4 V to 5.5 V
• 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)
• Control Inputs Can be Driven by TTL or 5-V/3.3-V CMOS Outputs
• Ioff Supports Partial-Power-Down Mode Operation
• Latch-Up Performance Exceeds 100 mA Per JESD 78, Class II
• ESD Performance Tested Per JESD 22
  • 2000-V Human-Body Model (A114-B, Class II)
  • 1000-V Charged-Device Model (C101)
• Supports I2C Bus Expansion
• Supports Both Digital and Analog Applications: USB Interface, Bus Isolation, Low-Distortion Signal Gating

• Configuration
• 2:1 SPDT
• Number of channels (#)
• 4
• Power supply voltage - single (V)
• 5
• Protocols
• Analog, JTAG, UART, I2C, SPI, RGMII, TDM, I2S
• Ron (Typ) (Ohms)
• 3
• CON (Typ) (pF)
• 16.5
• Bandwidth (MHz)
• 200
• Operating temperature range (C)
• -40 to 85
• Features
• Undershoot protection
• Input/output continuous current (Max) (mA)
• 128
• Rating
• Catalog

SN74CBT3257C的完整型号有：SN74CBT3257CD、SN74CBT3257CDBQR、SN74CBT3257CDBR、SN74CBT3257CDR、SN74CBT3257CPW、SN74CBT3257CPWR、SN74CBT3257CPWRG4、SN74CBT3257CRGYR，以下是这些产品的关键参数及官网采购报价：

SN74CBT3257CD，工作温度：-40 to 85，封装：SOIC (D)-16，包装数量MPQ：40个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网SN74CBT3257CD的批量USD价格：.377（1000+）

SN74CBT3257CDBQR，工作温度：-40 to 85，封装：SSOP (DBQ)-16，包装数量MPQ：2500个，MSL 等级/回流焊峰值温度：Level-2-260C-1 YEAR，引脚镀层/焊球材料：NIPDAU，TI官网SN74CBT3257CDBQR的批量USD价格：.177（1000+）

SN74CBT3257CDBR，工作温度：-40 to 85，封装：SSOP (DB)-16，包装数量MPQ：2000个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网SN74CBT3257CDBR的批量USD价格：.177（1000+）

SN74CBT3257CDR，工作温度：-40 to 85，封装：SOIC (D)-16，包装数量MPQ：2500个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网SN74CBT3257CDR的批量USD价格：.177（1000+）

SN74CBT3257CPW，工作温度：-40 to 85，封装：TSSOP (PW)-16，包装数量MPQ：90个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网SN74CBT3257CPW的批量USD价格：.377（1000+）

SN74CBT3257CPWR，工作温度：-40 to 85，封装：TSSOP (PW)-16，包装数量MPQ：2000个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网SN74CBT3257CPWR的批量USD价格：.177（1000+）

SN74CBT3257CPWRG4，工作温度：-40 to 85，封装：TSSOP (PW)-16，包装数量MPQ：2000个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网SN74CBT3257CPWRG4的批量USD价格：.204（1000+）

SN74CBT3257CRGYR，工作温度：-40 to 85，封装：VQFN (RGY)-16，包装数量MPQ：3000个，MSL 等级/回流焊峰值温度：Level-2-260C-1 YEAR，引脚镀层/焊球材料：NIPDAU，TI官网SN74CBT3257CRGYR的批量USD价格：.177（1000+）

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