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參數(shù)資料
| 型號： | T6311A |
| 廠商： | TM Technology, Inc. |
| 英文描述： | Low-Dropout, Constant-Current White LED Bias Supply |
| 中文描述： | 低壓差，恒流白光LED偏置電源 |
| 文件頁數(shù)： | 6/9頁 |
| 文件大?。?/td> | 56K |
| 代理商： | T6311A |
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Functional Description
The T6311A provides constant current bias
supply for white LED designs. The T6311A
uses a single resistor to set the bias current for
up to three LEDs. LED bias currents are
matched to 0.3% by the T6311A current
matching architecture (Fig. 1). Supply current
(I
EN
) is a low 40uA in normal operation and
0.05uA when disabled. The T6311A offers
several advantages over using ballast resistors,
such as improved LED to LED brightness
matching, lower bias variation with supply
voltage changes, significantly lower dropout
voltage,
and
in
significantly
improved
T6311A achieves a 200mV dropout with a
9mA load on each output. For circuits
requiring only one or two LEDs, leave unused
LED outputs unconnected.
Enable Input
EN powers the input of the T6311A. Drive
EN high (> 2.5V) to enable the device; drive
EN low (< 2.2V) to disable the device. When
driven high, EN draws 40μA to power the IC.
Driving EN low forces LED1, LED2, LED3,
LED4 and SET into a high-impedance state.
Setting the Output Current
SET controls the LED bias current. Current
flowing into LED1, LED2, LED3 and LED4
is 240 times greater than the current flowing
into SET. Set the output current as follows:
I
LED
= 240 ( (V
CTRL
- V
SET
) / R
SET
)
where V
SET
= 1.2V, V
CTRL
is an external
voltage between 1.8V and 5.5V, and R
SET
is
the resistor connected between V
CTRL
and
SET (Fig. 1).
Preliminary Product spec. T6311A
TM Technology Inc. reserves the right
P.6
to change products or specifications without notice.
Publication Date: JUN. 2005
Revision: C
some
applications,
efficiency.
The
Applications Information
Very Low-Cost, High-Efficiency Solution
(Fig. 2). A battery (single Li+ or three NiMH
cells) powers the LEDs directly. This is the
least expensive and most efficient architecture.
Due to the high forward voltage of white
LEDs (3.3V), the LED brightness may dim
slightly at the end of battery life. The T6311A
current regulating architecture and low
dropout greatly minimize this effect compared
to using simple ballast resistors. The enable
function of the T6311A turns on and off the
LEDs. An existing low-dropout regulator is
used as V
CTRL
.
Brightness Adjustment Using a DAC
(Fig. 3). A DAC is used as V
CTRL
such that
the LED brightness may be dynamically
adjusted to eliminate factory calibration. A
battery (single Li+ or three NiMH cells) or a
regulated power source drives the LEDs.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| T6311A-D | Low-Dropout, Constant-Current White LED Bias Supply |
| T6311A-X | Low-Dropout, Constant-Current White LED Bias Supply |
| T6313A | Low Noise, High Efficiency WhiteLED Charge Pump |
| T6313A-AF | Low Noise, High Efficiency WhiteLED Charge Pump |
| T6313A-BF | Low Noise, High Efficiency WhiteLED Charge Pump |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| T6311A-D | 制造商:TMT 制造商全稱:TMT 功能描述:Low-Dropout, Constant-Current White LED Bias Supply |
| T6311A-X | 制造商:TMT 制造商全稱:TMT 功能描述:Low-Dropout, Constant-Current White LED Bias Supply |
| T6313A | 制造商:TMT 制造商全稱:TMT 功能描述:Low Noise, High Efficiency WhiteLED Charge Pump |
| T6313A-AF | 制造商:TMT 制造商全稱:TMT 功能描述:Low Noise, High Efficiency WhiteLED Charge Pump |
| T6313A-BF | 制造商:TMT 制造商全稱:TMT 功能描述:Low Noise, High Efficiency WhiteLED Charge Pump |
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