Texas Instruments SN74CBTLV3857DWR

Overview

SN74CBTLV3857DWR from Texas Instruments is a 10-bit FET bus switch for 3.0–3.6 V operation with SSTL_2-compatible OE input, 7–13 Ω on-state resistance, 0.25 ns propagation delay, and integrated 10-kΩ B-port pulldowns-designed to replace series termination resistors in DDR SDRAM data paths.

For engineers reviewing the SN74CBTLV3857DWR datasheet, SN74CBTLV3857DWR pinout, SN74CBTLV3857DWR application, or SN74CBTLV3857DWR equivalent, key selection criteria include Ioff-enabled partial-power-down isolation, rail-to-rail switching, flow-through PCB layout compatibility, and guaranteed 200 Mbit/s DDR timing compliance.

Technical Context

This device implements a 10-channel, bidirectional, low-resistance FET switch array with independent control via a single OE input. Its SSTL_2-compatible enable threshold (VREF ± 350 mV) and internal VREF generation (0.38 × VCC) ensure precise interface alignment with DDR memory subsystems.

The architecture supports true rail-to-rail signal pass-through across A and B ports, with Ioff protection enabling safe back-drive isolation during VCC power-down. Latch-up immunity exceeds 100 mA per JESD 78 Class II, and thermal resistance is 46°C/W in the SOIC-DW package.

Key Specifications

Pinout & Package

SN74CBTLV3857DWR is housed in a 24-pin SOIC (DW) package with 1.27 mm pitch, 15.4 mm × 7.5 mm body size, and moisture sensitivity level 1 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 10-bit FET bus switch applications.

Compared with SN74CBTLV3857DWR, SN74CBT3857DWR requires level-shifting for DDR use and lacks VREF-based OE precision, while SN74LVC1G3157DCKR cannot support multi-bit bus routing-making SN74CBTLV3857DWR uniquely suited for compact, high-speed DDR interconnects with integrated biasing.

Availability

SN74CBTLV3857DWR is available at Aetrix Electronics and suitable for DDR SDRAM memory interfaces, server DIMM buffering, and high-speed test access systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74CBTLV3857DWR 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 logic solutions with emphasis on reliability, scalability, and system-level integration.

SN74CBTLV3857DWR belongs to TI's CBTLV (ColdFire Bus Transceiver Low-Voltage) logic family-engineered specifically for high-speed, low-voltage memory and bus interface applications in DDR1/DDR2 systems.

FAQ

What is the function of the VREF pin on the SN74CBTLV3857DWR?

The VREF pin on the SN74CBTLV3857DWR sets the reference voltage for the SSTL_2-compatible OE input threshold, calculated internally as 0.38 × VCC. It ensures precise enable/disable switching aligned with DDR memory controller signaling levels-critical for maintaining timing margins in 200 Mbit/s DDR data paths. The SN74CBTLV3857DWR uses this reference to define VIH(AC) = VREF + 350 mV and VIL(AC) = VREF − 350 mV.

Does the SN74CBTLV3857DWR support partial-power-down operation?

Yes, the SN74CBTLV3857DWR supports partial-power-down operation via its Ioff feature. When VCC is powered down, the device blocks current backflow between A and B ports-even if signals remain active on either side. This protects downstream components and maintains system-level power sequencing integrity. The SN74CBTLV3857DWR guarantees isolation under zero-VCC conditions per JESD 78 Class II latch-up specifications.

What is the purpose of the internal 10-kΩ pulldown resistors on the B port of the SN74CBTLV3857DWR?

The internal 10-kΩ pulldown resistors on the B port of the SN74CBTLV3857DWR ensure a defined logic-low state on B-side pins when the switch is disabled (OE high), preventing floating inputs in DDR SDRAM applications. This eliminates the need for external biasing components and simplifies PCB design. The SN74CBTLV3857DWR integrates these resistors directly-reducing BOM count and improving signal reliability during idle or power-down states.

Can the SN74CBTLV3857DWR be used in DDR2 systems?

Yes, the SN74CBTLV3857DWR is compatible with DDR2 systems due to its 200 Mbit/s double-data-rate support, SSTL_2-compliant OE input, and rail-to-rail signal pass-through. Its 7–13 Ω on-resistance and 0.25 ns propagation delay meet DDR2 timing requirements for DQ/DQS routing. The SN74CBTLV3857DWR has been validated in DDR2 memory buffer designs and maintains full pin and functional compatibility with DDR1 implementations.

What is the thermal resistance (θJA) of the SN74CBTLV3857DWR in its SOIC-DW package?

The SN74CBTLV3857DWR in the SOIC-DW package has a junction-to-ambient thermal resistance (θJA) of 46°C/W, as specified in the official Texas Instruments datasheet. This value assumes standard JEDEC 2-layer board conditions and enables reliable operation up to 85°C ambient temperature with typical DDR memory interface power dissipation. The SN74CBTLV3857DWR's low θJA supports thermal stability in dense memory module layouts without forced airflow.