Texas Instruments SN74CBTLV3857DWG4

Overview

SN74CBTLV3857DWG4 from Texas Instruments is a 10-bit FET bus switch designed for 3-V to 3.6-V operation with SSTL_2-compatible enable input, 7–13 Ω on-state resistance, rail-to-rail switching, and internal 10-kΩ B-port pulldowns-optimized for DDR SDRAM data-path termination replacement in high-speed memory interfaces.

For engineers reviewing the SN74CBTLV3857DWG4 datasheet, SN74CBTLV3857DWG4 pinout, SN74CBTLV3857DWG4 application, or SN74CBTLV3857DWG4 equivalent, key selection criteria include its Ioff-enabled partial-power-down capability, 0.25-ns propagation delay, 24-pin SOIC (DW) package, and compatibility with 200 Mbit/s DDR SDRAM timing requirements.

Technical Context

This device implements a flow-through architecture with 10 independent bidirectional FET switches, each controlled by a single active-low OE signal referenced to VREF = 0.38 × VCC. Its SSTL_2-compatible OE threshold (VIH = VREF + 350 mV, VIL = VREF − 350 mV) ensures direct interfacing with DDR SDRAM controller outputs without level-shifting.

The switch supports rail-to-rail signal transmission across A and B ports, with on-resistance calibrated to eliminate external series termination resistors in SSTL_2 data paths. Ioff protection isolates ports during power-down, preventing backflow current when VCC = 0 while maintaining high-impedance isolation between A and B sides.

Key Specifications

Pinout & Package

SN74CBTLV3857DWG4 is housed in a 24-pin SOIC (DW) package with 300-mil width and 1.27-mm lead pitch. Thermal resistance θJA is 46°C/W, supporting industrial temperature operation from −40°C to 85°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTLV3857DWG4, SN74CBT3857DW requires external level-shifting for DDR use and adds 8–12 Ω on-resistance, degrading signal integrity; SN74LVC1G3157DCKR lacks the 10-bit parallel architecture, pulldowns, and VREF-based SSTL_2 interface needed for drop-in DDR integration.

Availability

SN74CBTLV3857DWG4 is available at Aetrix Electronics and suitable for DDR SDRAM memory interfaces, high-speed bus isolation, and partial-power-down systems requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for SN74CBTLV3857DWG4 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 company headquartered in Dallas, Texas, delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

SN74CBTLV3857DWG4 belongs to TI's CBTLV (ColdFire Bus Transceiver Low-Voltage) logic family, engineered specifically for high-speed DDR memory interconnects with emphasis on low on-resistance, SSTL_2 compatibility, and Ioff-enabled power management.

FAQ

What is the function of the VREF pin on the SN74CBTLV3857DWG4?

The VREF pin on the SN74CBTLV3857DWG4 sets the reference voltage for SSTL_2-compatible input thresholds, defined as 0.38 × VCC. It determines VIH (VREF + 350 mV) and VIL (VREF − 350 mV) for the OE input, ensuring precise timing alignment with DDR memory controller signals. This pin must be connected directly to the VCC supply node for correct operation of SN74CBTLV3857DWG4 in DDR applications.

Does the SN74CBTLV3857DWG4 support hot-plug or partial-power-down operation?

Yes, the SN74CBTLV3857DWG4 supports partial-power-down operation via its Ioff feature. When VCC = 0 V, the device blocks current flow between A and B ports, preventing damaging backfeed from live signal lines into unpowered circuitry. This behavior is specified and tested per JESD 78 Class II, making SN74CBTLV3857DWG4 suitable for hot-swap DDR memory modules and power-gated subsystems.

What is the purpose of the internal 10-kΩ pulldown resistors on the B port of the SN74CBTLV3857DWG4?

The internal 10-kΩ pulldown resistors on the B port of the SN74CBTLV3857DWG4 ensure a defined logic-low state on DDR SDRAM data pins when the switch is disabled (OE high) or when the SDRAM is unpowered. This eliminates floating inputs that could cause leakage, noise coupling, or unintended activation-reducing design complexity and eliminating the need for external pull-down components in SN74CBTLV3857DWG4-based DDR layouts.

Can the SN74CBTLV3857DWG4 replace series termination resistors in DDR SDRAM designs?

Yes, the SN74CBTLV3857DWG4 is explicitly designed to replace discrete series termination resistors in SSTL_2 DDR data paths. Its 7–13 Ω typical on-state resistance matches the target impedance range for DDR signal integrity, allowing direct placement between controller and SDRAM without additional resistors-verified in TI's application guidance for 200 Mbit/s DDR systems using SN74CBTLV3857DWG4.

What package type and dimensions does the SN74CBTLV3857DWG4 use?

The SN74CBTLV3857DWG4 uses a 24-pin SOIC (DW) package with 300-mil body width and 1.27-mm lead pitch. Its thermal resistance is θJA = 46°C/W, and it operates across −40°C to 85°C. The DW package is RoHS-compliant, moisture-sensitive level 1, and compatible with standard reflow profiles-making SN74CBTLV3857DWG4 suitable for high-volume automated assembly in industrial and computing applications.