ADJD-J823 查看數據表（PDF） - Avago Technologies
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ADJD-J823 Datasheet PDF : 18 Pages
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High Level Description
A hardware reset (by asserting XRST) should be performed
before starting any operation. It is assumed that factory
calibration was performed prior deployment of ADJD-J823.
Calibration is discussed at the end of this section.
The user controls and configures the device by program-
ming a set of internal registers through a serial interface. At
the start of application, the following register data must be
written to it:
• Frequency registers
• Setup data
• Calibration data
• Bright and color input registers.
The register data is usually gathered during a calibration
process which is performed once in manufacturing. Factory
calibration is needed at a system level to map the integrated
tri-color sensor’s reading (device dependent) with a standard
device independent color space.
Once the register data is entered, the feedback operation
begins; the device starts to sample the RGB sensor using
the internal ADC. That data is compared to a user-controlled
color point target. The PWM duty factor for each channel is
adjusted in response to any error signal generated by that
comparison operation.
Thus, the actual color produced by the LEDs is maintained
close to the target.
There are three methods to operate the device. They are
differentiated by the technique in which the register data
is stored and used. The three figures below describe the
methods. NVPROM stands for Non-Volatile Programmable
Read-Only Memory such as an EEPROM.
Independent NVPROM
The NVPROM is independent from the device. During
factory calibration, the host must read the register data
from the device and write it to the NVPROM. At the start
of application, the host must read the register data from
the NVPROM and write it back to the device, after which
the device will wait for further instructions in normal
mode.
NVPROM
HOST
CONTROLLER
SDASLV
SCLSLV
DEVICE
Dedicated NVPROM in Interactive Mode
A dedicated NVPROM is connected to the device. During
factory calibration, the host can instruct the device to
upload the register data to the NVPROM. At the start of
application, the host can instruct the device to download
the register data from the NVPROM, after which the de-
vice will wait for further instructions in normal mode. The
serial interface protocol between device and NVPROM
is hard coded. A standard NVPROM such as a serial I2C
EEPROM with address 0x50 (7-bit) must be used.
HOST
CONTROLLER
SDASLV
SDAPROM
SCLSLV DEVICE SCLPROM NVPROM
Dedicated NVPROM in Standalone Mode
A dedicated NVPROM is connected to the device. During
factory calibration, the host can instruct the device to
upload the register data to the NVPROM. The difference
versus Interactive Mode is that, in application, the device
itself will download the register data and immediately
after, enter normal mode. Then, it will start driving the
PWM channels to achieve a default target color point.
The default color point is programmed after factory
calibration. A host controller is not necessary during ap-
plication. The serial interface protocol between device
and NVPROM is hard coded. So, a standard NVPROM
such as a serial I2C EEPROM with address 0x50 (7-bit)
must be used.
DEVICE
SDAPROM
SCLPROM
NVPROM
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