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參數(shù)資料
| 型號(hào)： | LP3944ISQ |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 顯示驅(qū)動(dòng)器 |
| 英文描述： | RGB/White/Blue 8-LED Fun Light Driver |
| 中文描述： | LED DISPLAY DRIVER, QCC24 |
| 文件頁數(shù)： | 6/12頁 |
| 文件大小： | 249K |
| 代理商： | LP3944ISQ |
Application Notes
THEORY OF OPERATION
The LP3944 takes incoming data and feed them into several
registers that control the frequency and the duty cycle of the
LEDs. Two prescaler registers and two PWM registers pro-
vide two individual rates to dim or blink the LEDs (for more
information on these registers, refer to
Table 1. LP3944
REGISTER
TABLE
).
The
microprocessor can program each LED to be in one of four
states—on, off, DIM0 rate or DIM1 rate. One read-only
registers provide status on all 8 LEDs. The LP3944 can be
used to drive RGB LEDs and/or single-color LEDs to create
a colorful, entertaining, and informative setting. This is par-
ticularly suitable for accessory functions in cellular phones
and toys. Any LED pins not used to drive LED can be used
for General Purpose Parallel Input/Output (GPIO) expan-
sion.
baseband
controller/
The LP3944 is equipped with Power-On Reset that holds the
chip in a reset state until V
reaches V
during power up.
Once V
is achieved, the LP3944 comes out of reset and
initializes itself to the default state.
To bring the LP3944 into reset, hold the RST pin LOW for a
period of TW. This will put the chip to its default state. The
LP3944 can only be programmed after RST signal is HIGH
again.
I
2
C DATA VALIDITY
The data on SDA line must be stable during the HIGH period
of the clock signal (SCL). In other words, state of the data
line can only be changed when CLK is LOW.
I
2
C START AND STOP CONDITIONS
START and STOP bits classify the beginning and the end of
the I
2
C session. START condition is defined as SDA signal
transitioning from HIGH to LOW while SCL line is HIGH.
STOP condition is defined as the SDA transitioning from
LOW to HIGH while SCL is HIGH. The I
2
C master always
generates START and STOP bits. The I
2
C bus is considered
to be busy after START condition and free after STOP con-
dition. During data transmission, I
2
C master can generate
repeated START conditions. First START and repeated
START conditions are equivalent, function-wise.
TRANSFERRING DATA
Every byte put on the SDA line must be eight bits long with
the most significant bit (MSB) being transferred first. The
number of bytes that can be transmitted per transfer is
unrestricted. Each byte of data has to be followed by an
acknowledge bit. The acknowledge related clock pulse is
generated by the master. The transmitter releases the SDA
line (HIGH) during the acknowledge clock pulse. The re-
ceiver must pull down the SDA line during the 9th clock
pulse, signifying an acknowledge.Areceiver which has been
addressed must generate an acknowledge after each byte
has been received.
After the START condition, a chip address is sent by the I
2
C
master. This address is seven bits long followed by an eighth
bit which is a data direction bit (R/W). The LP3944 hardwires
bits 7 to 4 and leaves bits 3 to 1 selectable, as shown in
Figure 3
. For the eighth bit, a “0” indicates a WRITE and a
“1” indicates a READ. The LP3944 supports only a WRITE
during chip addressing. The second byte selects the register
to which the data will be written. The third byte contains data
to write to the selected register.
20085306
FIGURE 1. I
2
C Data Validity
20085307
FIGURE 2. I
2
C START and STOP Conditions
L
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相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LP3944ISQX | RGB/White/Blue 8-LED Fun Light Driver |
| LP3944 | RGB/White/Blue 8-LED Fun Light Driver |
| LP3945 | Battery Charge Management System |
| LP3945ILD | Battery Charge Management System |
| LP3945ILDX | Battery Charge Management System |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LP3944ISQ/NOPB | 功能描述:LED照明驅(qū)動(dòng)器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
| LP3944ISQEV | 功能描述:電源管理IC開發(fā)工具 LP3944 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LP3944ISQEV/NOPB | 制造商:Texas Instruments 功能描述:Evaluation Board For LED Driver 8Segment 2.5V/3.3V/5V T/R |
| LP3944ISQX | 功能描述:LED照明驅(qū)動(dòng)器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
| LP3944ISQX/NOPB | 功能描述:LED照明驅(qū)動(dòng)器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
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