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參數(shù)資料
| 型號： | AAT3131 |
| 廠商： | Advanced Analogic Technologies, Inc. |
| 英文描述： | High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications |
| 中文描述： | 高效率電荷泵分數(shù)電荷泵白光LED應(yīng)用 |
| 文件頁數(shù)： | 11/14頁 |
| 文件大小： | 329K |
| 代理商： | AAT3131 |
different efficiency values. One should refer to the
following two sections for explanations for each
operational mode.
Load Switch Mode Efficiency
The AAT3131 load switch mode is operational at all
times and functions alone to enhance device power
conversion efficiency when the condition exists
where VIN is greater then voltage across the load
connected to the constant current source outputs.
When in "Load Switch" mode, the voltage conver-
sion efficiency is defined as output power divided
by input power:
The expression to define the ideal efficiency (
η
)
can be rewritten as:
-or-
Charge Pump Section Efficiency
The AAT3131 contains a fractional charge pump
which will boost the input supply voltage in the
event where V
IN
is less than the voltage required
on the constant current source outputs. The effi-
ciency (
η
) can be simply defined as a linear voltage
regulator with an effective output voltage that is
equal to one and a half times the input voltage.
Efficiency (
η
) for an ideal 1.5x charge pump can
typically be expressed as the output power divided
by the input power.
In addition, with an ideal 1.5x charge pump, the
output current may be expressed as 2/3 of the
input current. The expression to define the ideal
efficiency (
η
) can be rewritten as:
For a charge pump with an output of 5 volts and a
nominal input of 3.5 volts, the theoretical efficiency is
95%. Due to internal switching losses and IC quies-
cent current consumption, the actual efficiency can
be measured at 93%. These figures are in close
agreement for output load conditions from 1mA to
100mA. Efficiency will decrease as load current
drops below 0.05mA or when level of V
IN
approach-
es V
OUT
. Refer to the Typical Characteristics section
for measured plots of efficiency versus input voltage
and output load current for the given charge pump
output voltage options.
Capacitor Selection
Careful selection of the four external capacitors
C
IN
, C1, C2, C
OUT
is important because they will
affect turn on time, output ripple and transient per-
formance. Optimum performance will be obtained
when low ESR (<100m
) ceramic capacitors are
used. In general, low ESR may be defined as less
than 100m
. A capacitor value of 1μF for all four
capacitors is a good starting point when choosing
capacitors. If the LED current sources are only
programmed for light current levels, then the
capacitor size may be decreased.
Capacitor Characteristics
Ceramic composition capacitors are highly recom-
mended over all other types of capacitors for use with
the AAT3131. Ceramic capacitors offer many advan-
tages over their tantalum and aluminum electrolytic
counterparts. A ceramic capacitor typically has very
low ESR, is lowest cost, has a smaller PCB footprint
and is non-polarized. Low ESR ceramic capacitors
help maximize charge pump transient response.
Since ceramic capacitors are non-polarized, they are
not prone to incorrect connection damage.
η
(%) = 100
V
OUT
1.5V
IN
η
= P
OUT
= V
OUT
×
I
OUT
= V
OUT
P
IN
V
IN
1.5I
OUT
1.5V
IN
η
= P
OUT
P
IN
η
(%) = 100
V
OUT
V
IN
η
= P
OUT
= V
OUT
×
I
OUT
= V
OUT
P
IN
V
IN
×
I
OUT
V
IN
η
= P
OUT
P
IN
AAT3131
High Efficiency 1X/1.5X Fractional
Charge Pump for White LED Applications
3131.2004.08.1.1
11
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AAT3131ITP-T1 | High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications |
| AAT3132 | High Efficiency 1.5X Fractional Charge Pump for White LED Applications |
| AAT3132A | High Efficiency 1.5X Fractional Charge Pump for White LED Applications |
| AAT3132AITP-1-T1 | High Efficiency 1.5X Fractional Charge Pump for White LED Applications |
| AAT3132ITP-1-T1 | High Efficiency 1.5X Fractional Charge Pump for White LED Applications |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AAT3131_08 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications |
| AAT3131ITP-T1 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications |
| AAT3132 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:High Efficiency 1.5X Fractional Charge Pump for White LED Applications |
| AAT3132A | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:High Efficiency 1.5X Fractional Charge Pump for White LED Applications |
| AAT3132AITP-1-T1 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:High Efficiency 1.5X Fractional Charge Pump for White LED Applications |
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