24-Output PWM LED Drivers
for Message Boards
The serial interface uses the continuously running
clock, CLKI, to synchronously transfer and latch data
(33MHz max). The MAX6974/MAX6975 sample inputs
DIN and LOADI on the rising edge of CLKI and update
outputs DOUT and LOADO on the rising edge of CLKI.
The MAX6974/MAX6975 specifications guarantee that
cascaded devices observe setup and hold timing from
device to device, making external buffers and clock
trees unnecessary, even in very large systems.
The high-speed CLKI, CLKO, DIN, and DOUT signals
use low-voltage differential signaling (LVDS), and the
less frequently changing control signals, LOADI and
LOADO, use standard CMOS. The differential signals
are generally referred to in unipolar shorthand; for
example, the statement “CLKI rising edge” means that
CLKI+ is rising, and CLKI- is falling.
The MAX6974/MAX6975 use LVDS drivers with differential
signaling (300mV nominal logic swing around a +1.2V
bias) and cascaded CMOS control signals to minimize
signal-path EMI and simplify interface timing and print-
ed-circuit board (PCB) layout. Note the differential
inputs for the first driver can be driven from +3.3V
CMOS using LVDS level translators, such as the
MAX9112 terminated with 110 Ω (see Figure 12).
A 25MHz to 33MHz clock frequency is recommended
to keep the display refresh rate high. When using the
MAX6975 in reduced global-intensity mode (GLB4 = 1
in configuration register), the recommended clock
frequency range is 6MHz to 33MHz.
Serial-Interface Protocol Structure
The MAX6974/MAX6975 serial interface transfers all
data and control functions using a protocol structure
consisting of header, data, and optional tail segments
transmitted in this sequence. The header and tail
CLKI+
CLKI-
t PD-CLKO
CLKO+
CLKO-
t SU-DIN
DIN+
t HD-DIN
DIN-
t PD-DOUT
DOUT+
DOUT-
t SU-LOADI
t HD-LOADI
LOADI
t PD-LOADO
LOADO
Figure 6. Serial-Interface Timing
16
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MAX6974ATL+T 功能描述:LED照明驱动器 24-Output PWM LED Driver RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N
MAX6974ATL-T 制造商:Maxim Integrated Products 功能描述:24-OUTPUT PWM LED DRIVERS FOR MESSA - Tape and Reel
MAX6974EVKIT 功能描述:LED 照明开发工具 MAX6974 Evaluation Kit RoHS:否 制造商:Fairchild Semiconductor 产品:Evaluation Kits 用于:FL7732 核心: 电源电压:120V 系列: 封装:
MAX6974EVKIT+ 功能描述:LED 照明开发工具 MAX6974 Evaluation Kit RoHS:否 制造商:Fairchild Semiconductor 产品:Evaluation Kits 用于:FL7732 核心: 电源电压:120V 系列: 封装:
MAX6975ATL 功能描述:LED显示驱动器 RoHS:否 制造商:Micrel 数位数量:5 片段数量: 安装风格:SMD/SMT 封装 / 箱体:PLCC-44 工作电源电压:4.75 V to 11 V 最大电源电流:10 mA 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装:Tube
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