LSF0101 datasheet(11/39 Pages) TI1

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Vref_A

Vref_B

GND

LSF0108

LSF0101, LSF0102, LSF0108

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SDLS966G – DECEMBER 2013 – REVISED FEBRUAURY 2016

Product Folder Links: LSF0101 LSF0102 LSF0108

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Functional Block Diagrams (continued)

Figure 5. LSF0108 Functional Block Diagram

8.3 Feature Description

The LSF family are bidirectional voltage level translators operational from 0.95 to 4.5 V (Vref_A) and 1.8 to 5.5 V

(Vref_B). This allows bidirectional voltage translations between 1 V and 5 V without the need for a direction pin in

open-drain or push-pull applications. LSF family supports level translation applications with transmission speeds

greater than 100 Mbps for open-drain systems using a 30-pF capacitance and 250-

Ω pullup resistor.

When the An or Bn port is LOW, the switch is in the ON-state and a low resistance connection exists between

the An and Bn ports. The low Ron of the switch allows connections to be made with minimal propagation delay

and signal distortion. Assuming the higher voltage is on the Bn port when the Bn port is HIGH, the voltage on the

An port is limited to the voltage set by Vref_A. When the An port is HIGH, the Bn port is pulled to the drain pull-

up supply voltage (Vpu#) by the pull-up resistors. This functionality allows a seamless translation between higher

and lower voltages selected by the user without the need for directional control.

The supply voltage (Vpu#) for each channel can be individually set up with a pull-up resistor. For example, CH1

can be used in up-translation mode (1.2 V

↔ 3.3 V) and CH2 in down-translation mode (2.5 V ↔ 1.8 V).

When EN is HIGH, the translator switch is on, and the An I/O is connected to the Bn I/O, respectively, allowing

bidirectional data flow between ports. When EN is LOW, the translator switch is off, and a high-impedance state

exists between ports. The EN input circuit is designed to be supplied by Vref_B. To ensure the high-impedance

state during power-up or power-down, EN must be LOW.

8.4 Device Functional Modes

Table 1 expresses the functional modes of the LSF devices.

(1)

EN is controlled by Vref_B logic levels and should be at least 1 V

higher than Vref_A for best translator.

Table 1. Function Table

INPUT EN(1) PIN

FUNCTION

An = Bn

H-Z

LSF0101 Datasheet(PDF) 11 Page - Texas Instruments