|
Linear 公司的LT8500是具有12位分辨率和解0MHz級聯串口的48路LED PWM發生器,輸入電壓3V-5.5V,有48個單獨的PWM輸出,高達6.1kHz的PWM頻率(PWMCK = 25MHz),主要用在大屏顯示器LED背光,單色,多色和全色LED顯示器,馬大哈控制,工業控制,ATE和機器人.本文介紹了LT8500主要特性,方框圖以及多種應用電路. 48-Channel LED PWM Generator with 12-Bit Resolution and 50MHz Cascadable Serial Interface The LTR8500 is a pulse width modulation (PWM) generator with 48 independent channels. Each channel has an individually adjustable 12-bit (4096-step) PWM register and a 6-bit (64-step) ±50% correction register. All controls are programmable via a simple serial data interface. Three banks of 16-channels each can be configured such that they operate 120° out-of-phase with each other. The LT8500 features two diagnostic information flags: synchronization error and open LED. The flags are sent, with additional state information, on the serial data interface during status read back. The 50MHz cascadable serial data interface includes buffering and skew-balancing, making the chip suitable for PWM intensive applications such as large screen LCD dynamic backlighting and mono-,multi- and full-color LED displays. The LT8500 is also ideally suited to control three LT3595A LED drivers. LT8500主要特性: 3V to 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 Steps) PWM Correction (±50% of Programmed PWM Width) Up to 6.1kHz PWM Frequency (PWMCK = 25MHz) Phase-Shift Option Reduces Switching Noise Directly Controls Three LT3595A 16-Channel LED Drivers Diagnostic Information: Sync Error/Open LED Flags 56-Pin (5mm × 9mm × 0.75mm) QFN Package LT8500應用: Large Screen Display LED Backlighting Mono-, Multi-, Full-Color LED Displays LED Billboards and Signboards Motor Control Industrial Control Automated Test Equipment Robotics 
圖1.LT8500方框圖
圖2.LT8500串行接口拓撲圖
圖3.LT8500采用5引腳拓撲驅動LT3595A的菊花鏈框圖
圖4.LT8500采用4引腳拓撲驅動LT3595A的菊花鏈框圖
圖5.單個LT8500驅動電阻鎮流的48個LED串電路圖
圖6.單個LT8500實現48個DAC通路圖 詳情請見: http://cds.linear.com/docs/Datasheet/8500f.pdf |
