LT8500_15 Datasheet, PDF (1/24 Pages) Linear Technology – 48-Channel LED PWM Generator with 12-Bit Resolution and 50MHz Cascadable Serial Interface

LT8500
48-Channel LED PWM Generator
with 12-Bit Resolution and 50MHz
Cascadable Serial Interface
Features
n _{3V to 5.5V Input Voltage}
n _{48 Independent PWM Outputs}
n _{TTL/CMOS Logic 50MHz Serial Data Interface}
n _{12-Bit (4096 Steps) PWM Width Resolution}
n _{6-Bit (64 Steps) PWM Correction}
(±50% of Programmed PWM Width)
n _{Up to 6.1kHz PWM Frequency (PWMCK = 25MHz)}
n _{Phase-Shift Option Reduces Switching Noise}
n _{Directly Controls Three LT3595A 16-Channel}
LED Drivers
n _{Diagnostic Information: Sync Error/Open LED Flags}
n _{56-Pin (5mm × 9mm × 0.75mm) QFN Package}
Applications
n _{Large Screen Display LED Backlighting}
n _{Mono-, Multi-, Full-Color LED Displays}
n _{LED Billboards and Signboards}
n _{Motor Control}
n _{Industrial Control}
n _{Automated Test Equipment}
n _Robotics
Description
The LT^®8500 is a pulse width modulation (PWM) genera-
tor 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.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Typical Application
48 PWM OUTPUTS
5-WIRE
SERIAL
DATA
INTERFACE
OSC
DIAGNOSTIC
CIRCUIT
•••••
PWM[48:1]
SDI
SDO
SCKI
SCK0
LDIBLANK
LT8500 (1)
PWMCK
OPENLED
48 PWM OUTPUTS
•••••
PWM[48:1]
SDI
SDO
SCKI
SCK0
LDIBLANK
LT8500 (2)
PWMCK
OPENLED
••••
••••
••••
••••
••••
48 PWM OUTPUTS
•••••
PWM[48:1]
SDI
SDO
SCKI
SCK0
LDIBLANK
LT8500 (N)
PWMCK
OPENLED
8500 TA01a
8500f
1