LSF0101 - 1-Bit Auto-Bidirectional Level Translator | Texas Instruments
MPN: LSF0101 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.28 | $0.28 |
| 10 | $0.24 | $2.40 |
| 100 | $0.15 | $15.00 |
| 500 | $0.12 | $60.00 |
| 1,000 | $0.09 | $90.00 |
LSF0101 Overview
A level translator (also called a voltage shifter or logic-level converter) is an interface IC that safely connects circuits operating at different supply voltages - for example a 1.8 V microcontroller communicating with a 3.3 V or 5 V peripheral. Level translators belong to the broader voltage translator / logic IC hierarchy within interface semiconductors, and the LSF0101 is the smallest, single-bit member of the TI/Nexperia LSF family.
Key features include automatic bidirectional operation with no DIR control signal, up-translation of up to 100 MHz and down translation of 100 MHz or more at a capacitive load of 30 pF or less, and 5 V tolerant I/O pins for TTL compatibility. According to the TI and Nexperia datasheets, the pass-gate (NFET) switch architecture delivers very low propagation delay and supports both open-drain two-wire buses and push-pull interfaces.
The reference-bias topology (VREF_A / VREF_B) defines the two voltage domains; the low-side reference is applied through the EN pin bias network and an analog pass switch connects the A and B pins. This makes the LSF0101 especially suitable for two-wire buses where direction changes asynchronously - something buffered push-pull translators cannot handle without a direction input.
Typical applications include I2C, SMBus, and PMBus level shifting, 1.8 V to 3.3 V or 5 V mixed-voltage MCU peripherals, industrial control buses, and mobile or wearable designs where the 1 x 0.8 mm X2SON footprint conserves board area.
Design consideration: the LSF family requires correct pull-up resistor sizing on open-drain buses to meet rise-time targets; the reference-side bias resistor (typically 200 kohm per TI datasheet guidance) sets translation speed, so verify its value against bus capacitance and data rate before production.
Drop-in alternatives for LSF0101 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LSF0101DTQR
✅ Drop-In📋 Reference alternative (not in catalog)
LSF0101GX
✅ Drop-In📋 Reference alternative (not in catalog)
LSF0102-Q1
⚡ Same Package✓ In Stock
Contact for price
View Datasheet →LSF0101 Specifications
| Function | 1-channel bidirectional multi-voltage level translator |
| Channels | 1 |
| Direction Control | Auto-bidirectional (no DIR pin) |
| Applications | Open-drain and push-pull |
| Up Translation Speed | Up to 100 MHz |
| Down Translation Speed | >= 100 MHz at <= 30 pF load |
| I/O Tolerance | 5 V tolerant I/O pins (TTL compatible) |
| Architecture | Pass-gate (NFET) switch, VREF_A / VREF_B bias |
| Package | 6-X2SON (1 x 0.8 mm) |
| Mounting Type | Surface Mount |
| Typical Bias Resistor | 200 kohm (reference-side, per TI datasheet guidance) |
| RoHS Status | Compliant |
| Lifecycle Status | Active |
LSF0101 Pin Configuration
| Pin 1 | VREF_B — B-side reference voltage (higher domain) |
| Pin 2 | B — B-side bidirectional I/O |
| Pin 3 | GND — Ground |
| Pin 4 | EN — Enable / low-side reference bias node (200 kohm to GND) |
| Pin 5 | A — A-side bidirectional I/O |
| Pin 6 | VREF_A — A-side reference voltage (lower domain) |
Typical Applications
LSF0101 is suitable for 6 applications: I2C Bus Level Shifting, PMBus Power Supply Management, Mixed-Voltage MCU Peripherals, Automotive Body and Control Modules, Wearables and Mobile Devices, Industrial Control and PLC I/O.
I2C Bus Level Shifting
The LSF0101's pass-gate NFET architecture is inherently bidirectional with no direction pin, matching the wired-AND open-drain behavior of I2C perfectly. Per the TI datasheet, it supports >= 100 MHz down-translation at <= 30 pF load, comfortably covering standard (100 kHz), fast (400 kHz), and fast-mode plus (1 MHz) I2C. Placed between a 1.8 V controller and a 3.3 V or 5 V sensor, each side pulls up through appropriately sized resistors; the 200 kohm reference-side bias resistor sets the translation speed, so verify it against bus capacitance and target data rate before production.
Recommended
PMBus Power Supply Management
PMBus power controllers and hot-swap monitors often run at 3.3 V while low-voltage microcontrollers and FPGAs operate at 1.8 V or lower. The LSF0101 bridges one PMBus line without a direction signal, essential because PMBus transactions change direction asynchronously at the protocol level. Its 5 V tolerant I/O covers legacy 5 V management buses, and its sub-1 mm X2SON footprint fits on crowded power-supply boards near POL converters. With 100 MHz class switching capability, PMBus speeds of 100-400 kHz see negligible propagation penalty, preserving bus timing margins across the voltage domain boundary.
Recommended
Mixed-Voltage MCU Peripherals
Microcontrollers such as the TI MSP430 and MSPM0 families running at 1.8 V frequently need to talk to 3.3 V EEPROMs, displays, and industrial sensors. The LSF0101 provides a single-line bridge with 5 V tolerant I/O, eliminating damage risk when a 5 V peripheral drives the B side. Because it also handles push-pull signals up to 100 MHz, it serves SPI chip-select, UART, and GPIO lines as well as open-drain buses. Reference the TI LSF datasheet bias network guidance: the low-side VREF through the EN pin and a 200 kohm resistor establish the low-domain switching threshold automatically.
Recommended
Automotive Body and Control Modules
The AEC-Q100 qualified LSF0102-Q1 family member extends LSF translation into automotive ECUs where 1.8 V MCUs interface with 3.3 V or 5 V sensors and LIN/CAN transceiver control lines. Using the same pass-gate architecture as the LSF0101, the family provides deterministic translation without direction pins - valuable in fault-tolerant automotive buses. TI reference designs pair LSF translators with TCAN and TLIN transceivers for body-domain modules. The X2SON package withstands standard AEC reflow profiles, and the 5 V tolerant I/O accommodates 5 V sensor outputs common in legacy vehicle platforms.
Recommended
Wearables and Mobile Devices
Space-constrained wearable and mobile designs benefit from the LSF0101's 6-X2SON package of just 1 x 0.8 mm - among the smallest level-shifter footprints in the industry. Battery-powered systems often mix a 1.2 V to 1.8 V application processor with 1.8 V or 3.3 V sensor hubs, touch controllers, and fuel gauges. The pass-gate switch adds essentially no static current path in the translated signal, helping standby power budgets, and no direction control line reduces both GPIO usage and firmware complexity on tightly pin-limited wearable MCUs handling I2C sensor buses.
Recommended
Industrial Control and PLC I/O
Industrial controllers mix legacy 5 V signaling with modern 3.3 V and 1.8 V logic. The LSF0101's 5 V tolerant I/O and TTL compatibility let one translated channel safely connect a low-voltage processor to 5 V proximity-sensor interface lines, optocoupler front ends, or SMBus-based power modules. The >= 100 MHz down-translation capability at <= 30 pF supports fast encoder or PWM feedback lines, not just slow buses. Per the TI datasheet, correct open-drain pull-up sizing keeps rise times within spec under the higher cable and connector capacitance typical of industrial backplanes, preserving noise margins in electrically noisy cabinets.
Recommended
Recommended Products Summary
Engineering reference data for LSF0101 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LSF0101DTQR | LSF0101GX | LSF0102-Q1 |
|---|---|---|---|---|
| Package | 6-X2SON (1 x 0.8 mm) | 6-X2SON (1 x 0.8 mm) - same | 6-X2SON (1 x 0.8 mm) - same | 6-X2SON (1 x 0.8 mm) - same package, different pinout (2-ch) |
| Brand | Texas Instruments | Texas Instruments | Nexperia | Texas Instruments |
| Channels | 1 | 1 | 1 | 2 |
| Direction Pin | Not required (auto-bidirectional) | Not required | Not required | Not required |
| Up Translation Speed | Up to 100 MHz | Up to 100 MHz | Up to 100 MHz | Up to 100 MHz |
| I/O Tolerance | 5 V tolerant (TTL compatible) | 5 V tolerant | 5 V tolerant | 5 V tolerant |
| Applications | Open-drain and push-pull | Open-drain and push-pull | Open-drain and push-pull | Open-drain and push-pull |
Key Differentiators
- True auto-bidirectional pass-gate with no DIR pin (vs SN74LVC1T45QDCKRQ1)
- Smallest footprint in the TI translator portfolio (vs TXS0102-Q1)
- Identical cross-brand second source available (vs LSF0101GX)
Design Notes
The reference-side bias resistor on the EN pin (typically 200 kohm per TI LSF datasheet guidance) sets the reference current that determines translation speed. Too large a value limits up-translation speed on capacitive buses; too small wastes current and can exceed EN node ratings. Always verify this value against your bus capacitance and target data rate, and never tie EN directly to a supply without the bias network.
The 6-X2SON (1 x 0.8 mm) package places its lands under the package body. Follow the TI datasheet land-pattern drawing exactly, use via-in-pad or short escape vias for the center connections, and keep A/B trace stubs under 10 mm for 100 MHz signals. Place the part within a few millimeters of the bus connector or IC pins to minimize added capacitance on open-drain lines.
On open-drain buses such as I2C, rise time is set by pull-up resistance and total bus capacitance, not by the LSF0101 itself. With <= 30 pF load the part supports >= 100 MHz down-translation, but a 4.7 kohm pull-up with 50 pF of bus capacitance will limit an I2C bus to standard-mode speeds. Compute RC rise time against the bus protocol rise-time limit and choose pull-ups accordingly per the TI LSF application guidance.
Compliance Information
RoHS compliant per TI product page. AEC-Q100 qualified versions exist in the family (LSF0102-Q1); the standard LSF0101 is not -Q1 qualified.
