General Description

The MY9942, 4 channels constant current LED driver with

14bits grayscale APDM (Adaptive Pulse Density Modulation)

control, supports standard / 4X DMX512 protocol and fully

differential interface suited for long distance parallel

applications. The distinctive DMX512 decoding approach

could decode precisely a standard DMX512 signal. And each

device loads one/two/three/four grayscale data according to

two slot selection pins and nine address setting pins (512

addresses). The differential interface provides wide

common-mode range to support long distance transmission

without common-ground power systems.

The device operates over 7V to 40V input voltage

range and provides 4 open-drain constant current sinking

outputs that are rated to 5 0 V and delivers up to 350mA

of high accuracy current to each string of LED. The current at

each output is programmable by means of four external

current setting resistors. The MY9942 provides the gamma

correction, gamma value is 2.2, to transform 8bits DMX data

to 14bits APDM data in order to enhance brightness contract.

The 14bits adaptive pulse density modulation makes sure

that the frame refresh rate is higher than 2KHz. And an

accurate oscillator is built in for free running APDM grayscale

control and DMX512 decoder.

Furthermore, MY9942 could drive High Power LED directly

by shorting the output channels and changing the slot data

number. The POL function makes MY9942 as a PWM

generator to support driving high power LEDs. MY9942 is

available in 28-pin SSOP/TSSOP packages and specified

over the -40°C to +85°C ambient temperature range.

Applications

❑ Standard DMX512 protocol system

❑ Full Color Mesh Display

❑ Architectural and Decorative Lighting

Features

✦ White / CW.WW / R.G.B / R.G.B.W applications

✦ One / Two / Three / Four slots data selection for different

LED configuration applications

✦ 7V to 40V Operating supply voltage

✦ 350mA maximum constant current output (Per channel)

✦ Current setting by 4 external resistors

✦ 50V Rated output channels for long LED strings

✦ ±1.5 (typ.) LED Current accuracy between channels

✦ ±3 (typ.) LED Current accuracy between chips

✦ Standard DMX512 protocol decoder (USITT DMX512-A)

✦ 4X DMX512 protocol selection (Baud rate=1MHz)

✦ Wide common-mode range for differential input signals

✦ Gamma, 2.2, to transform 8bits DMX to 14bits APDM data

✦ 14bits grayscale resolution with Adaptive Pulse Density

Modulation

✦ Frame refresh rate > 2000Hz as a LED driver

Frame refresh rate > 120Hz as a PWM generator

✦ Traditional non-scramble constant current waveform for

high power LED applications (PWM generator only)

✦ 512 addresses set by 9 external pins

✦ Built-in oscillator for grayscale control and DMX512

decoder

✦ -40°C to +85°C Ambient temperature range