LT8500

Obsolete

48-Channel LED PWM Generator with 12-Bit Resolution and 50MHz Cascadable Serial Interface

Data Sheet (Rev. C) Product Selection Table

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Overview

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 (6mm × 6mm × 0.78mm) TLA QFN Package

The LT8500 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.

Applications

Large Screen Display LED Backlighting
Mono-, Multi-, Full-Color LED Displays
LED Billboards and Signboards
Motor Control
Industrial Control
Automated Test Equipment
Robotics

Documentation

Data Sheet 1

LT8500: 48-Channel LED PWM Generator with 12-Bit Resolution and 50MHz Cascadable Serial Interface Data Sheet (Rev.C) 06/08/2016

User Guide 1

DC1552A - Demo Manual 01/25/2012

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Evaluation Kits

LT8500EUHH/LT3595AEUHH Demo Board | 48-Channel LED Driver (3× LT3595A) with PWM Generator (LT8500) and Serial Interface

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Product Details

Demonstration circuit 1552 showcases the LT8500, a 48-channel PWM generator and serial interface. It operates from a 30V to 45V input power supply and drives 48 channels of LED strings at 30mA and up to 32V each, although it can be adjusted for 50mA per string. The LT8500 drives 48 PWM channels that are tied directly to the PWM inputs of three separate LT3595A 16-channel step-down LED drivers. Each LED Driver can operate up to 45V input and provide up to 50mA LED current per channel.

The input to the LT8500 is a serial interface that can run up to 50MHz. The DC1552A has both an input and output connector and can be cascaded in a chain of two or more while being driven from a single serial interface.