Semtech Brings Phase-Shifted LED Backlight Drive to the Panel for the First Time for Ultrabook and Ultra-Thin Notebooks

SC5010 uses tiny, 2.2µH, 1mm height inductors for displays as thin as 4mm with high efficiency.

The SC5010 delivers higher efficiency when using the same size inductors as existing phase-shifted LED drivers, but unlike these devices, the SC5010 can operate with inductors that are up to 10X smaller while maintaining high efficiency. This enables LED drivers to be designed directly into the panel, even in ultra-thin applications. This is due to the sophisticated control loop architecture, which allows the use of inductors as small as 2.2µH (1mm height). The phase-shifted technology in the SC5010 also minimizes demand on the input and output capacitance offering the high efficiency of conventional non-phase shifted switching regulators, with significantly lower noise, less EMI (electromagnetic interference), and no need for noise filtering components.

“Now, for the first time, Ultrabook PC manufacturers can place efficient, phase-shifted LED drivers where they prefer them – next to the display, which, until now, has been a roadblock for Ultrabook and other very small form factor PCs,” said Athar Zaidi, Director of Marketing in Semtech’s Power Management Group. “The SC5010 offers a superior phase-shifted LED driver approach that significantly reduces the tradeoffs between inductor size and display efficiency.”

The SC5010 is an 8--channel boost LED driver that can power up to 112 LEDs, with currents up to 30mA per channel. The integrated control loop architecture of the device allows programmable switching frequencies as fast as 2.2MHz and is the key to enabling phase-shifted dimming using very small, low-profile inductors. Additionally, this approach reduces BOM size and cost by eliminating external compensation and noise filtering components.

Semtech’s innovative loop architecture also prevents display flicker and shutdown caused by line transients that can occur in automotive applications. This is achieved via the ultra-fast transient response of the SC5010, which allows it to handle line transients up to 10V/µs.

The SC5010 LED driver brings to market a rich feature set for the next generation of displays, including the flexibility of I2C and three PWM dimming control modes. It features a wide PWM input dimming range of 5000:1 at 200Hz and a dimming frequency range from 100Hz to 30kHz. The SC5010 also provides user-selectable 9 or 10 bit dimming resolution and a 5-bit analog dimming register that can be used in conjunction with PWM to increase the dimming resolution.
The phase shifted PWM dimming turns the LED strings on and off at the same frequency and the same duty cycle, but at different and equally spaced, automatically calculated phases. This reduces demand on the input/output capacitance to decrease radiated switching current, which improves EMI performance and dimming linearity.

The SC5010 delivers accurate backlight color te
mperature and uniform brightness across the entire display, with +/-1% channel-to-channel current matching and accuracy of +/-1.5%. Full protection functions include open LED and programmable shorted LED, adjustable over-voltage (OVP), and over-temperature protections; as well as under-voltage lock out (UVLO) shutdown.

Key Features of
• Wide VIN range: 4.5V to 27V; High VOUT range: up to 50V
• Uses ultra-thin, 2.2µH inductors (1mm height)
• 8 channel LED driver, up to 30mA per channel, drives up to 112 white LEDs
• String-by-string phase-shifted PWM dimming
• Fast transient response handles line transients up to 10V/µs
• High efficiency up to 92%
• Programmable switching frequency from 200kHz to 2.2MHz
• Low-profile 28-pin MLPQ package with exposed thermal pad: 4 x 4 x 0.6mm

Applications
The SC5010 is ideal for LCD backlighting in LCD monitor applications, including:
Automotive: Audio/Video Module, Seatback Infotainment, Instrument Cluster
Consumer Electronics: LCD Display Backlight
Ultrabook PC, Ultra-Mobile PC, Notebook PC, Tablet PC: LCD Display and Backlight