Linear Technology Launches 48-Channel PWM Generator
12-bit resolution LED dynamic control / Provides 48 DAC outputs

August 2, 2011 – Linear Technology Korea (CEO Hong Sa-kwak, www.linear.com ) announced the release of the Pulse Width Modulation (PWM) generator (Product Name: LT8500) featuring four independent channels. Each channel is equipped with an individually adjustable 12-bit (4,096-step) PWM register and a 6-bit (64-step) +50% correction register. All control is programmable via a simple TTL/CMOS 50 MHz serial data interface. The LT8500 can be used for a wide range of PWM-intensive applications, such as LED control, industrial, and robotics applications. For example, the LT8500 can be used in conjunction with three LT3595A (16-channel LED drivers) to provide 48 independently dimmable LED strings for locally dimmable LED backlights for large LCD displays. The correction register enables matching lighting outputs for each LED string.

The LT8500 operates over an input range of 3V to 5.5V, enabling operation on a wide range of standard power buses. For LED applications, each channel features individual 6-bit dot-compensated current regulation and 12-bit grayscale PWM dimming capabilities. The LT8500's 40ns on-time provides a very wide range of dynamic contrast ratios. Compensation and grayscale dimming are accessible via a serial interface for TTL/CMOS logic. The LT8500 provides two diagnostic flags to diagnose synchronization errors and LED open circuits. These flags are provided along with additional status information via the serial data interface during status readbacks. The 50MHz cascadable serial data interface, including buffering and skew balancing, facilitates design for PWM-intensive applications such as large-screen LCD dynamic backlights. The combination of minimal external components and a 5mm x 9mm QFN package provides a very compact solution footprint for multi-channel PWM applications.

The LT8500EUHH is available in a 56-pin 5mm x 9mm QFN package, with pricing starting at $2.95 per 1,000 units. The extended temperature version, the LT8500IUHH or Grade I, is also currently available, with pricing starting at $3.25 per 1,000 units. All versions are currently available for purchase. For more information, please visit www.linear.com/product/LT8500 .

Photo Caption: 48-channel PWM generator with 12-bit resolution and 50MHz serial interface

Product Features: LT8500

• 3V ~ 5.5V input voltage
• 48 independent PWM outputs
• TTL/CMOS logic 50MHz serial data interface
• 12-bit (4096 steps) PWM width resolution
• 6-bit (64-step) PWM correction (±50% of programmed PWM width)
• Maximum 6.1kHz PWM frequency (PWMCK = 25MHz)
• Phase switching option to reduce switching noise
• Directly control three 16-channel LED drivers LT3595A
• Diagnostic Information: Synchronization Error/Open LED Flag
• 56-pin (5mm × 9mm × 0.75mm) QFN package