Sponsored by: Texas Instruments. Battery-supply voltage variations can wreak havoc in automotive LED-backlight driver designs, but drivers leveraging the SEPIC topology help overcome those challenges.

Use of electronic displays continues to expand in automotive applications (Fig. 1). Behind the wheel, they’re replacing individual electromechanical instruments as well as complete instrument clusters. In infotainment, applications include radios, navigation displays, and headrest displays for rear passengers.

Augmented reality (AR) is another application. A head-up display superimposes an image on the windshield to give the driver key information while they’re concentrating on the road ahead.

Automotive displays such as these predominantly use liquid-crystal-display (LCD) technology. The illumination source is provided by multiple light-emitting diodes (LEDs) placed around the edge of the flat-panel display screen. This arrangement is known as an LED-backlit LCD.

The number of LEDs depends on application parameters such as the required brightness, the width of the display, and its resolution. The trend is toward displaying more information with larger, higher-resolution units. A 12-in. display with FHD (1920 × 1080) resolution, for example, might require up to 40 LEDs for a brightness of 1000 nits (candelas per square meter).

The LCD panel manufacturer determines the LED configuration. A single string of many LEDs in series is one option, but a more usual configuration is several shorter series strings arranged in parallel.

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LED Driver Fundamentals

The goal of the LED backlight driver is to keep the LED brightness at the desired value independent of changes in temperature, supply voltage, or other variables. The brightness of an LED is proportional to its forward current when the device is biased with a forward voltage (VF). VF varies with color: for backlight white LEDs, VF ≈ 3.0 V at 80 mA @25°C. The forward voltage is also temperature-dependent—1 mV/°C is typical—and process variations can add another 200 mV.

Over a −40 to 125°C operating range, an 8-in. LCD with 15 LEDs arranged in three strings of five therefore requires an LED supply voltage of between 14.175 and 16 V.

The simplest LED driver circuit consists of a power source, the LED string, and a series resistor to limit the current. However, more sophisticated backlight drivers typically regulate the current with a constant-current sink and add the capability to control the brightness.

Many LED backlight drivers in non-automotive applications can rely on a stable power supply. For example, notepads and cellphones use one or more 3.7-V Li-Ion battery cells, and an industrial application might have a system power supply of 36 V or 48 V. Check out Texas Instruments’ portfolio of LED drivers for more information.

In an automotive application, though, the power source originates with the vehicle battery, not exactly a stable, well-regulated power source. The voltage on the battery line (VBATT) is nominally 12 V, but this can vary widely during the operational life of the vehicle. There are several reasons for this variation, such as normal battery charging, transient events, faults, and mistakes.

Other equities research analysts have also recently issued reports about the company. Robert W. Baird reaffirmed a buy rating and set a $46.00 price objective on shares of Methode Electronics in a research note on Tuesday. ValuEngine upgraded Methode Electronics from a hold rating to a buy rating in a report on Saturday, September 30th. FBR & Co reiterated a buy rating on shares of Methode Electronics in a report on Thursday, August 31st. B. Riley reiterated a buy rating and set a $49.00 target price on shares of Methode Electronics in a report on Wednesday, June 28th. Finally, BidaskClub lowered Methode Electronics from a buy rating to a hold rating in a report on Tuesday, June 20th. One analyst has rated the stock with a sell rating and five have issued a buy rating to the company. The stock has an average rating of Buy and an average price target of $48.50.

Shares of Methode Electronics (MEI) traded up 1.66% during midday trading on Wednesday, hitting $46.05. The stock had a trading volume of 296,717 shares. Methode Electronics has a one year low of $29.85 and a one year high of $46.40. The firm’s 50-day moving average price is $41.89 and its 200-day moving average price is $41.10. The firm has a market capitalization of $1.70 billion, a PE ratio of 18.72 and a beta of 0.76.

Methode Electronics (NYSE:MEI) last announced its quarterly earnings data on Thursday, August 31st. The electronics maker reported $0.60 EPS for the quarter, topping analysts’ consensus estimates of $0.48 by $0.12. Methode Electronics had a return on equity of 18.11% and a net margin of 11.16%. The business had revenue of $201.20 million during the quarter, compared to analysts’ expectations of $189.40 million. During the same period in the previous year, the firm earned $0.57 earnings per share. The firm’s quarterly revenue was up 4.8% compared to the same quarter last year. On average, equities analysts predict that Methode Electronics will post $2.58 EPS for the current year.

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The company also recently declared a quarterly dividend, which will be paid on Friday, October 27th. Stockholders of record on Friday, October 13th will be issued a $0.09 dividend. The ex-dividend date of this dividend is Thursday, October 12th. This represents a $0.36 dividend on an annualized basis and a dividend yield of 0.78%. Methode Electronics’s dividend payout ratio (DPR) is 14.63%.

Institutional investors have recently modified their holdings of the company. Acrospire Investment Management LLC lifted its holdings in shares of Methode Electronics by 22.2% in the second quarter. Acrospire Investment Management LLC now owns 2,751 shares of the electronics maker’s stock valued at $113,000 after purchasing an additional 500 shares in the last quarter. Meeder Asset Management Inc. bought a new stake in shares of Methode Electronics in the second quarter valued at about $122,000. Riverhead Capital Management LLC lifted its holdings in shares of Methode Electronics by 87.3% in the second quarter. Riverhead Capital Management LLC now owns 2,996 shares of the electronics maker’s stock valued at $123,000 after purchasing an additional 1,396 shares in the last quarter. Tower Research Capital LLC TRC bought a new stake in shares of Methode Electronics in the second quarter valued at about $132,000. Finally, Ameritas Investment Partners Inc. bought a new stake in shares of Methode Electronics in the first quarter valued at about $135,000. Institutional investors own 89.82% of the company’s stock.

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