Preliminary
3 Channels Constant Current LED Driver With
Protocol and Differential Interface
MY9931
MY-Semi
Cascade DMX512
General Description
Features
The MY9931, 3 channels constant current LED driver with ✦ R.G.B applications
14bits grayscale APDM (Adaptive Pulse Density Modulation)
control, supports standard DMX512 protocol and fully
differential interface suited for long distance cascade
applications. The distinctive DMX512 decoding approach
could decode precisely a standard DMX512 signal. The
differential interface provides wide common-mode range to
support long distance transmission without common-ground
power systems.
✦ 7V to 40V Operating supply voltage
✦ 60mA Maximum constant current output (Per channel)
✦ Current setting by 3 external resistors
✦ 40V Rated output channels for long LED strings
✦ ±1.5% (typ.) LED Current accuracy between channels
✦ ±3% (typ.) LED Current accuracy between chips
✦ Auto-addressing cascade architecture
The device operates over 7V to 40V input voltage
range and provides 3 open-drain constant current sinking
outputs that are rated to 4 0 V and delivers up to 60mA
of high accuracy current to each string of LED. The current at
each output is programmable by means of three external
current setting resistors. The MY9931 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.
✦ Standard DMX512 protocol decoder (USITT DMX512-A)
✦ Distinctive differential output corresponding with
DMX512 format for long distance cascade
✦ Wide common-mode range for differential input signals
✦ Non-polarity connection for differential data input
✦ 14bits grayscale resolution with Adaptive Pulse Density
Modulation
✦ Gamma, 2.2, to transform 8bits DMX to 14bits APDM data
✦ 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)
✦ Built-in oscillator for grayscale control and DMX512
decoder
The POL function makes MY9931 as a PWM generator to
support driving high power LEDs. MY9931 is available in
SOP16 packages and specified over the -40°C to +85°C
ambient temperature range.
✦ -40°C to +85°C Ambient temperature range
Applications
Order information
❑ Standard DMX512 protocol system
❑ Full Color Mesh Display
PART
PIN PACKAGE
MY9931SD
SOP16-150mil-1.27mm
2500 pcs/Reel
❑ Architectural and Decorative Lighting
Typical Operating Circuits
Pin Configuration
Apr. 2012 Ver. 0.3
MY-Semi Inc.
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For pricing, delivery, and ordering information, pleases contact MY-Semi Inc. at +886-3-560-1668,
or email to INFO@MY-Semi.com.tw or visit MY-Semi’s website at www.MY-Semi.com.tw
