Munich, February 10, 2026 - There are various reasons why the display driving function of a product may need to be modified, but reducing the system's power consumption is one of the main motivations. An LCD display is always on in a device and is responsible for most of the energy consumption. Reducing the power consumption of the display driving function would greatly help to achieve a better energy budget in the long term. For battery-driven applications, new regulations often define new battery lifetimes for products that cannot be achieved with existing designs. In order to continue selling these products, customers must review the products' available energy budgets and take dedicated action. In addition, LCD contrast issues can also lead to redesigns when end customers complain about poor LCD performance due to poor display contrast.

 

Epson's 16-bit or 32-bit ARM Cortex M0+ microcontrollers, which utilise proven low-power technology, are the perfect solution for achieving high display driving performance with low power consumption. For this reason, many battery-driven applications use Epson microcontrollers as an "intelligent" LCD driver. It would also be possible to use Epson MCUs as the main MCU for the application. (Figure 1)

 

The lowest power consumption is achieved when the host MCU can be put into sleep mode for as long as possible. A system with an Epson 'intelligent' LCD driver can keep the host CPU in sleep mode for as long as possible, provided the application does not require it to handle tasks (e.g. sensor data handling) that cannot be supported by the LCD driver. An 'intelligent' LCD driver can take over application-specific tasks from the host CPU, such as storing look-up tables for LCD temperature compensation, which are usually stored in the host CPU memory. Another advantage is that Epson MCUs can still operate at 1.2 V for display control, even when the host CPU is inactive. Most SoCs only operate at a minimum supply voltage of 1.8 V. For display control functions, an 'intelligent' LCD driver can support several LCD memory pages, an auto-scroll/blinking function, or the storage of ASCII fonts or calibration data, while the host CPU can be put into sleep mode. The remaining RAM capacity can also be used as backup memory for the host CPU, and the Epson 'intelligent' LCD driver can detect the battery voltage level using the SVD (Supply Voltage Detection) circuit. A lot of Epson MCU sample software is available to facilitate the quick and smooth development of MCU LCD driver software. To save costs, Epson also offers the option of programming products in its own factory, which makes sense if the LCD driver firmware does not change.

 

       

 

 

 

Figure 1: Epson low power LCD driving concepts as Intelligent LCD driver (left picture) or as Main MCU (right picture)      

	Intelligent LCD driver	Main MCU
Display contrast	high
Display interface	direct
Power consumption (Display Update Mode)	5µA*
Power consumption (Display Driving Mode)	3µA*
Power consumption (Display OFF mode)	0.3µA
Running application	-	X

Note: *including Segment LCD 16SEG x 2COM where typ. power consumption for such a segment LCD can be estimated of around 2µA

 

To achieve the best LCD performance and lowest driving power consumption, there are a few key parameters that should match between the characteristics of the 'intelligent' LCD driver and the characteristics of the LCD liquid crystal. Therefore, it is sometimes necessary to consult with LCD suppliers regarding LCD characteristics to ensure the best possible match with LCD driver characteristics. The characteristics of LCD drivers vary depending on the panel load, i.e. the panel size, drive duty, the number of display pixels and the display contents. Recommendations from LCD suppliers on how to set parameters such as drive duty, bias or frame frequency are useful for selecting a suitable 'intelligent' LCD driver. Epson MCUs offer a wide range of integrated LCD drivers, from small 12 SEG x 4 COM segment LCDs to 128 SEG x 32 COM. They support drive duty from static to 1/32 and bias from ½ to 1/5. The final contrast and current consumption must be evaluated when the LCD panel is connected.

To achieve this, a stable V_LCD voltage level is mandatory, as is a low drive duty. Epson's 16-bit or 32-bit ARM Cortex M0+ microcontrollers offer, depending on the size of the panel, either the option of an external power supply or an internal voltage booster circuit to maintain a stable VLCD voltage level (see Figure 3). Using an internal voltage booster for smaller panels would eliminate the need for external components and reduce costs. However, for larger or more complex LCD panels, an external power supply may be more beneficial. 

       

         

 

Figure 3: LCD driver circuit with integrated voltage booster

 

 

In case V_LCD voltage level is unstable when supply voltage is decreasing LCD contrast is declining like showing in Figure 4 (right image).

 

Figure 4 : LCD display contrast with stable V_LCD (left image) or unstable V_LCD (right image)

The V_LCD varies with operating temperature (see the red curve in Figure 5). LCD datasheets often only specify the VLCD voltage at 25°C. In this case, the characteristics of the VLCD over temperature need to be checked with the LCD vendor to ensure that the internal LCD voltage booster can keep the V_LCD stable over the LCD's operating temperature range. Figure 5 shows an example of how the V_LCD can vary if the LCD needs to be operated from -20°C to +85°C. To compensate for a ΔVLCD drift over temperature, the VLCD can be adjusted using Epson's intelligent LCD drivers. (In Figure 5, this is marked as blue.)

 

In order to design low-power display systems, it is essential to understand the relationship between LCD duty, LCD bias, LCD frame frequency and LCD voltage behaviour. The duty cycle affects the brightness and flicker behaviour of the LCD, while biasing ensures the proper operation and longevity of the LCD liquid crystal. Proper management of these parameters is important for optimised LCD performance. With its long-standing experience in designing low-power LCD systems, Epson can support customers with its expertise. If you have any questions or need support in selecting a suitable 'intelligent' LCD driver product, please feel free to contact an Epson representative.

 

 

 

About Epson Europe Electronics GmbH
Epson Europe Electronics GmbH is a marketing, engineering and sales company and the European headquarter for electronic devices of the Seiko Epson Corporation, Japan. Since 1989 located in Munich/Germany with 50 employees, Epson Europe Electronics GmbH has several European sales representatives and a European-wide network of distributors. Epson Europe Electronics GmbH provides value added services for timing devices, semiconductors, sensors and sensing systems targeted to various markets like industrial, automotive, medical, and communication. Epson products are recognized for energy saving, low power, small form factors and rapid time to market. More information about Epson Europe Electronics GmbH is available on the internet under www.epson-electronics.de

About Epson
Epson is a global technology leader whose philosophy of efficient, compact and precise innovation enriches lives and helps create a better world. The company is focused on solving societal issues through innovations in home and office printing, commercial and industrial printing, manufacturing, visual and lifestyle. Epson’s goal is to become carbon negative and eliminate use of exhaustible underground resources such as oil and metal by 2050.
Led by the Japan-based Seiko Epson Corporation, the worldwide Epson Group generates annual sales of more than JPY 1 trillion.
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