Vref_A

VCCB

EN

200 k

A1

A2

B1

B2

GND

LSF0108-Q1

Vref_B

3.3 V

Device

3.3 V

RB2

RB1

0.1 µF

RA1

RA2

R1

R2

1.8 V –

V

1.8 V –

V

Device

5

5

LSF010x-Q1

Figure 9-5. Single Supply Translation with 3.3 V Supply

The steps to select the resistor values for R1 and R2 are as follows:

1. Select a value for R1. Typically, 1 MΩ is used to reduce current consumption.

2. Plug in values for your system into the following equation. Note that Vref_A is the lowest voltage in the

system. VCCB is the primary supply and R1 is the selected value from step 1.

R2 =  200 103 × R1 × VREFA

200 103 + R1 VCCB − VREFA − 0.85 × R1 

(4)

The single supply used must be at least 0.8 V larger than the lowest desired translation voltage. The voltage at

Vref_A must be selected as the lowest voltage to be used in the system. The LSF evaluation module (LSF-EVM)

contains unpopulated pads to place R1 and R2 for single supply operation testing. For an example single supply

translation schematic and details, see the Single Supply Translation with the LSF Family video.

LSF0102-Q1

SDLS969B – MAY 2018 – REVISED MAY 2023

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