Texas Instruments LSF0102DCTR

Overview

LSF0102DCTR from Texas Instruments is a 2-channel auto-bidirectional multi-voltage level translator for open-drain and push-pull interfaces, supporting 0.95V ↔ 1.8/2.5/3.3/5V translation, ≤30pF load up to 100MHz down/100MHz+ up translation, 8-pin SM8 package, and −40°C to 125°C operation - deployed in I²C, SMBus, and MDIO interconnects between mixed-voltage SoCs and peripherals.

For engineers reviewing the LSF0102DCTR datasheet, LSF0102DCTR pinout, LSF0102DCTR application, or LSF0102DCTR equivalent, key selection concerns include bidirectional voltage translation without direction control, Vref_A/Vref_B biasing requirements, EN pin connection to Vref_B via 200kΩ resistor, R_ON ≤10Ω at 1.8V→5V, and thermal resistance (R_θJA = 220.0°C/W) in SM8 packaging.

Technical Context

The LSF0102DCTR implements a passive MOSFET-based switch architecture-not buffered-enabling true auto-bidirectional translation with no DIR pin. Its dual-reference design uses Vref_A (0.95–5.5V) and Vref_B (1.8–5.5V) to define low- and high-side voltage domains independently per channel.

Translation direction is determined dynamically by signal polarity: when A or B is LOW, the internal pass transistor turns ON, creating a low-impedance path; when both are HIGH, the switch is OFF and outputs are clamped to their respective reference voltages. EN must be tied directly to Vref_B and pulled up to VCCB (not Vref_A) via 200kΩ for proper biasing and enable functionality.

Key Specifications

Pinout & Package

LSF0102DCTR uses the DCT (SM8) 8-pin surface-mount package: 2.95mm × 4.0mm footprint, exposed pad optional, compatible with standard reflow profiles. Pin numbering follows TI's top-view convention with pin 1 at bottom-left corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TXS0102DSGR and PCA9306DCUR, LSF0102DCTR uniquely delivers 5V-tolerant I/O, EN-controlled Hi-Z state, and seamless open-drain compatibility - making it the only option for telecom MDIO and industrial PMBus where direction pins are unavailable and 5V peripherals coexist.

Availability

LSF0102DCTR is available at Aetrix Electronics and suitable for industrial sensor hubs, telecom MDIO interfaces, server PMBus monitoring, and USB-C power delivery systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LSF0102DCTR 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 50 years of innovation in precision analog and interface solutions.

The LSF family was designed specifically for auto-bidirectional multi-voltage translation in open-drain and push-pull systems - targeting I²C, SMBus, PMBus, MDIO, and GPIO interconnects in telecom, industrial, and enterprise infrastructure.

FAQ

What is the correct way to connect the EN pin on LSF0102DCTR?

The EN pin on LSF0102DCTR must be tied directly to the Vref_B pin and pulled up to the high-side supply (VCCB) through a 200kΩ resistor. This configuration allows Vref_B to regulate EN and properly bias the internal pass transistors. Driving EN directly with a push-pull output violates the bias requirement and causes translation failure. The LSF0102DCTR datasheet explicitly prohibits this in Section 7.3.2 and Figure 7-1.

Can LSF0102DCTR translate between 1.2V and 5V?

Yes, LSF0102DCTR supports 1.2V ↔ 5V translation per its specified 0.95V ↔ 5V range. Vref_A must be set to 1.2V and Vref_B to 5V, with EN tied to Vref_B and pulled up to 5V. The device achieves ≤10Ω R_ON at this combination (per Table 5.5), maintaining valid LOW levels. However, ensure downstream 1.2V receivers tolerate 5V-tolerant I/O leakage - confirmed in LSF0102DCTR's I_OH/I_OL specs.

Does LSF0102DCTR require external pull-up resistors on both sides?

LSF0102DCTR requires pull-up resistors on the high side (B ports) for up-translation and open-drain operation. Pull-ups on the low side (A ports) are optional - only needed if the A-side receiver has leakage >1µA or uses open-drain drivers. For push-pull A-side drivers, no A-side pull-up is required. This flexibility is documented in Section 7.4.1.2 and Table 8-3 of the LSF0102DCTR datasheet.

What is the maximum capacitive load LSF0102DCTR can drive at 100MHz?

LSF0102DCTR supports ≥100MHz translation only at ≤30pF total capacitive load (including trace, probe, and receiver capacitance). At 50pF, maximum speed drops to 40MHz. These values are measured per Figure 6-1 test conditions and appear in Sections 5.6–5.9 of the LSF0102DCTR datasheet. Exceeding 30pF at 100MHz causes timing violations and signal integrity loss.

How does LSF0102DCTR handle mixed-voltage translation across its two channels?

LSF0102DCTR supports independent voltage translation per channel: A1/B1 and A2/B2 operate with the same Vref_A and Vref_B references but can interface different peripheral pairs (e.g., A1/B1 for 1.8V↔3.3V I²C, A2/B2 for 1.2V↔5V GPIO). No cross-talk occurs because each channel uses isolated pass transistors - verified in the functional block diagram (Figure 7-2) and Section 7.4 of the LSF0102DCTR datasheet.