Texas Instruments 74CBTLV3857DBQRG4

Overview

74CBTLV3857DBQRG4 from Texas Instruments is a 10-bit FET bus switch designed for 3.0–3.6 V operation with SSTL_2-compatible enable input, 7–13 Ω on-state resistance, 0.25 ns propagation delay, and integrated 10-kΩ B-port pulldowns-optimized for DDR SDRAM data-path termination in high-speed memory interfaces.

For engineers reviewing the 74CBTLV3857DBQRG4 datasheet, 74CBTLV3857DBQRG4 pinout, 74CBTLV3857DBQRG4 application, or 74CBTLV3857DBQRG4 equivalent, key selection criteria include rail-to-rail switching capability, Ioff partial-power-down support, flow-through package layout, and compatibility with 200 Mbit/s double-data-rate signaling environments.

Technical Context

This device implements a passive FET-based bidirectional switch architecture with no internal logic or level-shifting circuitry. Each of the ten A–B channels operates as an analog pass gate controlled solely by the OE signal, enabling direct connection or high-impedance isolation between ports without voltage translation or timing overhead.

It features dedicated internal 10-kΩ pulldown resistors on all B-port terminals and a 50-kΩ pullup on OE, eliminating external bias components in SSTL_2 systems. The VREF pin provides a 0.38×VCC reference for AC-coupled control thresholding, supporting both DC and AC input level detection per JEDEC SSTL_2 specifications.

Key Specifications

Pinout & Package

74CBTLV3857DBQRG4 is housed in a 24-pin SSOP (Shrink Small Outline Package) with 0.65 mm pitch and flow-through pin arrangement optimized for straight PCB routing between memory controller and DDR SDRAM devices.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTLV3245APWRE4 and 74CBTLV3244DBQR, the 74CBTLV3857DBQRG4 uniquely integrates VREF generation, SSTL_2 OE compatibility, and 10-kΩ B-port pulldowns-making it the only single-package solution for 10-bit DDR DQ termination without external bias components.

Availability

74CBTLV3857DBQRG4 is available at Aetrix Electronics and suitable for DDR SDRAM memory interfaces, high-speed data bus isolation, and partial-power-down embedded systems requiring stable component supply and long-term industrial availability.

Supply support for 74CBTLV3857DBQRG4 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 and embedded processing solutions for industrial, automotive, communications, and computing markets.

The CBTLV logic family targets high-speed, low-voltage bus switching applications-specifically engineered for DDR memory subsystems, where signal integrity, power efficiency, and integration of biasing functions are critical design constraints.

FAQ

What is the function of the VREF pin on the 74CBTLV3857DBQRG4?

The VREF pin on the 74CBTLV3857DBQRG4 outputs a precision 0.38×VCC voltage used to set the AC input thresholds for the OE signal. This enables compliant SSTL_2 interface behavior, where VIH(AC) = VREF + 350 mV and VIL(AC) = VREF − 350 mV-ensuring reliable enable/disable timing in DDR clock domains. The 74CBTLV3857DBQRG4 does not require external reference circuitry.

Does the 74CBTLV3857DBQRG4 support hot-plug or partial-power-down operation?

Yes, the 74CBTLV3857DBQRG4 supports partial-power-down operation via its Ioff feature. When VCC = 0 V, the device blocks current flow between A and B ports-even if signals remain active on either side-preventing damage from backfeed. This makes the 74CBTLV3857DBQRG4 suitable for DDR modules requiring dynamic power gating or hot-swap capability.

Can the 74CBTLV3857DBQRG4 replace series termination resistors in DDR designs?

Yes, the 74CBTLV3857DBQRG4 is explicitly designed to eliminate external series termination resistors in SSTL_2 DDR data paths. Its typical on-state resistance of 7–13 Ω matches standard DDR termination requirements, and its rail-to-rail switching preserves signal amplitude-making the 74CBTLV3857DBQRG4 a functional and layout-efficient replacement for discrete 22-Ω resistors.

What are the key differences between the 74CBTLV3857DBQRG4 and SN74CBTLV3245APWRE4?

The 74CBTLV3857DBQRG4 offers 10-bit switching, integrated VREF, SSTL_2-compatible OE input, and 10-kΩ B-port pulldowns-features absent in the 8-bit SN74CBTLV3245APWRE4. While both are low-voltage bus switches, only the 74CBTLV3857DBQRG4 meets full DDR DQ interface requirements without external bias components.

Is the 74CBTLV3857DBQRG4 pin-compatible with other packages in the same family?

No-the 74CBTLV3857DBQRG4 uses the DBQ (SSOP-24) package with a specific flow-through pinout. It shares functional equivalence but not mechanical or electrical pin compatibility with DW (SOIC-24), PW (TSSOP-24), or DGV (TVSOP-24) variants due to differing pin assignments and thermal characteristics. Layout reuse requires package-specific footprint validation.