Texas Instruments TXB0108NMER

Overview

TXB0108NMER from Texas Instruments is an 8-bit bidirectional voltage-level translator with auto-direction sensing, supporting 1.2V–3.6V on the A port and 1.65V–5.5V on the B port (VCCA ≤ VCCB), ±15kV HBM ESD protection on the B port, 4μA max ICC, and Ioff partial-power-down capability. It enables seamless logic-level translation between mixed-voltage domains in mobile processor-peripheral interfaces.

For engineers reviewing the TXB0108NMER datasheet, TXB0108NMER pinout, TXB0108NMER application, or TXB0108NMER equivalent, key selection criteria include VCCA/VCCB supply compatibility, auto-direction operation without control lines, high-impedance state behavior during power sequencing, and package-specific thermal performance for compact handheld PCBs.

Technical Context

The TXB0108NMER implements a buffered, edge-rate-accelerated architecture with one-shot circuits to enhance data rate without external direction control. Its dual-rail design isolates A-port logic (VCCA-referenced) from B-port logic (VCCB-referenced), enabling true bidirectional translation across non-overlapping voltage domains.

VCC isolation ensures all outputs enter high-impedance when either VCCA or VCCB is at GND; OE is referenced solely to VCCA and forces 3-state when low. The device supports push-pull CMOS only - open-drain signals require TXS-series alternatives.

Key Specifications

Pinout & Package

nFBGA-20 package, 2.50 mm × 3.00 mm body size, 0.5-mm pitch, bottom-side ball grid array with exposed thermal pad connected to GND per TI layout guidelines.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage-level translation applications.

Compared with TXB0108NMER, TXB0104NMER reduces footprint and cost for 4-signal use cases but lacks channel count for parallel interfaces, while TXS0108EVMR adds open-drain flexibility at the expense of speed, power efficiency, and VCC isolation - making TXB0108NMER optimal for high-density, high-speed, mixed-rail push-pull applications.

Availability

TXB0108NMER is available at Aetrix Electronics and suitable for smartphone, tablet, and handheld device designs requiring stable component supply, automotive infotainment module integration, and industrial HMI controller development.

Supply support for TXB0108NMER 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 specializing in analog, embedded processing, and connectivity technologies, with over 90 years of innovation in power management and signal chain solutions.

The TXB0108 product line delivers auto-direction voltage translation for portable electronics, designed specifically to simplify mixed-voltage SoC-peripheral interfacing while meeting stringent ESD, power, and timing requirements.

FAQ

What is the maximum allowable voltage difference between VCCA and VCCB for reliable operation of the TXB0108NMER?

The TXB0108NMER requires VCCA ≤ VCCB at all times. While VCCA may range from 1.2V to 3.6V and VCCB from 1.65V to 5.5V, the absolute constraint is that VCCA must never exceed VCCB. For example, 3.3V on VCCA mandates VCCB ≥ 3.3V - using 3.3V on both rails is valid, but 3.3V on VCCA with 2.5V on VCCB violates the specification and risks malfunction or damage. This condition is enforced by internal comparator design.

Does the TXB0108NMER support open-drain or wired-OR bus topologies like I²C?

No, the TXB0108NMER is designed exclusively for push-pull CMOS logic translation and does not support open-drain configurations. Its output drivers lack weak pull-up capability and cannot tolerate bus contention from external pull-ups. For I²C, SMBus, or 1-wire applications, TI recommends the TXS0108E series instead. Using TXB0108NMER on an open-drain bus will result in incorrect logic levels and potential signal integrity failure.

How does the OE pin behave during power-up, and what is the recommended biasing strategy for TXB0108NMER?

The OE pin is referenced to VCCA and must be held low during power-up to ensure all A/B ports remain in high-impedance until both VCCA and VCCB are stable. TI specifies tying OE to GND via a pulldown resistor; minimum value depends on driver strength but 10 kΩ is commonly used. Leaving OE floating risks metastability, unintended translation, or bus contention - especially critical in systems where VCCA and VCCB power up at different rates.

What thermal considerations apply to the TXB0108NMER in its nFBGA-20 (NME) package?

The TXB0108NMER in nFBGA-20 has RθJA = 131.4°C/W and RθJB = 83.2°C/W. To maintain junction temperature ≤125°C at 85°C ambient, average power dissipation must stay below ~320 mW. TI mandates soldering the exposed thermal pad directly to a solid GND plane with ≥4 thermal vias (0.3-mm diameter) to achieve specified RθJB. Without proper thermal pad connection, junction temperature rise exceeds safe limits under sustained 100 Mbps operation.

Can the TXB0108NMER translate signals between a 1.2V FPGA bank and a 5V microcontroller peripheral?

Yes - the TXB0108NMER explicitly supports 1.2V on VCCA (A port) and 5V on VCCB (B port), satisfying the voltage range requirement. However, signal integrity must be verified: at 5V VCCB, VOLB is guaranteed ≤0.4V and VOHB ≥ VCCB – 0.4V = 4.6V, ensuring noise margins >0.4V for standard TTL thresholds. Data rate is limited to 20 Mbps in this configuration per TI's switching characteristics tables, not the 100 Mbps maximum achievable at matched rails.