AN-CM-382 Low-Voltage Bidirectional Level Shifter

Oct 22, 2026

Describes how to design and operate a bidirectional low-voltage level shifter with enable functionality for I2C communication up to 1 MHz using Renesas GreenPAK dual-supply devices, specifically SLG47528 and SLG47525. Explains the need for level shifting across different VDD ranges, highlights oscillator features and package/pin differences, and outlines configuration rules for universal pins versus pins with restrictions, including OE-based input/output behavior.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages9

Reading Time23 min

AccessFree to download

References

Terms and Definitions

Introduction

Design Operation

Conclusion

Revision History

Contents 1. References...................................................................................................................................................... 1 2. Terms and Definitions ................................................................................................................................... 1 3. Introduction .................................................................................................................................................... 2 4. Design Operation ........................................................................................................................................... 3 5. Conclusion ..................................................................................................................................................... 7 6. Revision History ............................................................................................................................................ 8 1. References For related documents and software please visit GreenPAK™ Programmable Mixed-Signal Products | Renesas Download our free Go Configure Software Hub [1] to open configuration ( .gp) files [2], review and edit the proposed circuit design. Use GreenPAK development tools [3] to evaluate the configuration on the development board or to program an IC and use it in a circuit. Find out more in a complete library of application notes [4] featuring design examples as well as explanations of features and blocks within the GreenPAK IC. Download SLG47528 [5] and SLG47525 [6] datasheets to get more details on each IC features and parameters. [1] Go Configure Software Hub , Software download and user guide [2] AN-CM-382 [Low_Voltage_Bidirectional_Level_Shifter.gp5](Low_Voltage_Bidirectional_Level_Shifter.gp5), GreenPAK design file [3] GreenPAK Development Tools , GreenPAK development tools webpage [4] GreenPAK Application Notes , GreenPAK application notes library [5] SLG47528 Datasheet [6] SLG47525 Datasheet [7] Dual Supply GreenPAK , Dual supply VDD GreenPAK webpage 2. Terms and Definitions I2C Inter-integrated circuit (bus) IC Integrated circuit IO Input/output LUT Look-up table 3. Introduction Modern systems are increasingly becoming more complex in order to satisfy the needs of the user, to be competitive on the market , and to provide their products with unique functions. In most cases, this leads to the use of various elements, among which there may be those that work in different voltage ranges. This may be due to better technical performance in a particular voltage range, lower current consumption, less noise, lower IC price, etc. Level Shifters are needed to provide communication between circuit elements operating between different supply voltages. They are based on dual VDD chips that have pins with switching thresholds corresponding to VDD1 and VDD2 . We remind you the Renesas portfolio includes GreenPAK ICs with dual VDD supply operation. More information about these devices can be found in link [7] in the References section. A new generation dual supply GreenPAK ICs , which includes the SLG47528 and SLG47525, is characterized by their wide voltage ranges of VDD1: 1.71 V – 5.50 V and VDD2: 0.95 V – 1.98 V. This feature makes them unique, making it possible to work with low voltages. A block diagram of a level shifter based on SLG47528 or SLG47525 ICs is shown in Figure 1. Figure 1 : Typical Block Diagram for Bidirectional Level Shifting The SLG47525 is a smaller version of the SLG47528 . These ICs are very similar in terms of functionality and internal components. One of the main differences is the size of the package and number of pins: 2 mm x 2.2 mm 14-pin (SLG47525) and 2 mm x 3 mm 20-pin (SLG47528) . The SLG47525 , unlike the SLG47528, does not have a temperature sensor. Both chips , in addition to having a 25 kHz / 2 MHz oscillator, also have a built-in 25 MHz oscillator that m

FAQs

Why are level shifters needed in these systems?

Level shifters provide communication between circuit elements operating at different supply voltages, enabling reliable signal transfer across VDD1 and VDD2 ranges.

What distinguishes SLG47528 and SLG47525 for the bidirectional level shifter?

They are functionally similar, but differ in package size and pin count, and SLG47525 lacks a temperature sensor present in SLG47528.

How does the enable function control IO direction in the design?

When the OE input receives a logic 0, the IO operates as an input; when it receives a logic 1, the IO operates as an output. Pins without OE must be preconfigured as input or output.

Oct 22, 2026

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