Texas Instruments LSF0102DDFR

Overview

LSF0102DDFR from Texas Instruments is a 2-channel auto-bidirectional multi-voltage level translator for open-drain and push-pull interfaces, supporting up to 100MHz down translation and 40MHz up/down translation at 50pF load, with voltage translation between 0.95V ↔ 1.8/2.5/3.3/5V, 1.2V ↔ 1.8/2.5/3.3/5V, and other combinations, used in I²C, SMBus, PMBus, and MDIO signal bridging in telecom infrastructure.

For engineers reviewing the LSF0102DDFR datasheet, LSF0102DDFR pinout, LSF0102DDFR application, or LSF0102DDFR equivalent, key selection considerations include its directionless operation, 8-pin DDF (SOT-23) package, 1.8–5.5V Vref_A/Vref_B range, <10Ω on-resistance at 64mA, and EN-controlled high-impedance state for power sequencing.

Technical Context

The LSF0102DDFR implements a passive MOSFET-based switch architecture-no internal buffers or direction control logic-enabling true bidirectional translation by dynamically biasing internal pass transistors via Vref_A and Vref_B. Its EN pin must be tied directly to Vref_B and pulled up to VCCB via 200kΩ to enable translation; when EN is low, all I/Os enter high-impedance state.

Down translation occurs when the B-side (higher voltage) drives LOW, turning on the switch to pull the A-side LOW; up translation occurs when the A-side (lower voltage) is HIGH, disabling the switch and allowing external pull-up on B-side to define the HIGH level. Signal integrity depends on external pull-up resistor sizing, capacitive load ≤50pF, and proper decoupling of Vref_B with 0.1µF.

Key Specifications

Pinout & Package

LSF0102DDFR uses the DDF package: 8-pin SOT-23, 2.9mm × 2.8mm body, with flow-through pinout optimized for compact PCB routing and minimal trace stubs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TXS0102DSGR and PCA9306DCUR, the LSF0102DDFR uniquely combines auto-bidirectional operation, EN-controlled Hi-Z, push-pull/open-drain flexibility, and wide Vref_A/Vref_B ranges-making it the only option supporting mixed-mode translation (e.g., 1.8V↔3.3V and 1.8V↔5V on same device) without external logic.

Availability

LSF0102DDFR is available at Aetrix Electronics and suitable for telecom infrastructure, industrial sensor hubs, and enterprise server power management requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for LSF0102DDFR 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 specializing in analog and embedded processing technologies, with leadership in interface, power management, and signal chain solutions.

The LSF family-including LSF0102DDFR-is designed specifically for seamless, pin-efficient voltage translation in multi-rail systems where open-drain and push-pull interfaces coexist, targeting telecom, industrial, and computing applications demanding zero-direction-pin operation.

FAQ

What is the correct way to connect the EN pin on the LSF0102DDFR?

The EN pin on the LSF0102DDFR must be tied directly to the Vref_B pin and pulled up to the high-side supply (VCCB) via a 200kΩ resistor. This configuration allows Vref_B to regulate EN and properly bias internal switches. Driving EN directly with a push-pull output violates the bias requirement and risks malfunction. The LSF0102DDFR will not translate correctly if EN is left floating or connected to a fixed logic level independent of Vref_B.

Can the LSF0102DDFR translate between 1.0V and 5V?

Yes-the LSF0102DDFR supports 1.0V ↔ 5V translation, as confirmed in its datasheet's voltage pair table under "0.95V ↔ 1.8/2.5/3.3/5V" and electrical characteristics showing operation down to Vref_A = 1.0V with Vref_B = 5V. At this combination, R_ON is 10Ω (typical) at 10mA, ensuring reliable LOW-level conduction. The LSF0102DDFR maintains full functionality across its specified Vref_A (0.95–5.5V) and Vref_B (1.8–5.5V) ranges.

Does the LSF0102DDFR require external pull-up resistors on both sides?

Yes-external pull-up resistors are mandatory on the B-side (high-voltage side) for up translation, and recommended on the A-side for open-drain receivers with leakage >1µA. For push-pull-to-push-pull configurations, A-side pull-ups may be omitted only if both drivers are actively controlled and never simultaneously drive opposite states. The LSF0102DDFR itself contains no internal pull-ups; all pull-up current flows through external resistors, and their values must be sized per TI's Equation 3 to limit pass-transistor current to ≤15mA.

How does the LSF0102DDFR handle mixed-voltage translation across its two channels?

The LSF0102DDFR supports mixed-voltage translation per channel using shared Vref_A and Vref_B pins-e.g., Channel 1 can translate 1.8V ↔ 3.3V while Channel 2 translates 1.8V ↔ 5V, provided both B-side pull-ups connect to their respective VPU supplies. Vref_A sets the low-side clamp voltage for both channels; Vref_B biases the EN and internal switches. This capability makes the LSF0102DDFR suitable for heterogeneous bus architectures where multiple voltage domains converge on a single controller.

What thermal considerations apply to the LSF0102DDFR in a 2.9mm × 2.8mm SOT-23 package?

In its DDF (SOT-23) package, the LSF0102DDFR has a junction-to-ambient thermal resistance (R_θJA) of 243.3°C/W. At 64mA per channel and 8Ω R_ON, worst-case power dissipation is ~33mW-resulting in <8°C junction rise above ambient. No heatsinking is required, but a minimum 25mm² copper pour connected to GND improves thermal performance. The LSF0102DDFR is rated for operation up to +125°C ambient, with derating unnecessary below 100mW total dissipation.