参数资料
| 型号： | EHE004 |
| 厂商： | Mide Technology Corporation |
| 文件页数： | 20/24页 |
| 文件大小： | 0K |
| 描述： | BOARD ENERGY HARVESTING |
| 产品培训模块： | EHE004 Piezoelectric Energy Harvesting Conditioning Circuit |
| 特色产品： | Energy Harvesting Power Products |
| 标准包装： | 1 |
| 系列： | Volture™ |
| 主要目的： | 电源管理，能量收集 |
| 嵌入式： | 否 |
| 已用 IC / 零件： | LTC3588 |
| 主要属性： | 用户可选择的输出电压 |
| 次要属性： | 最多 100mA 输出 |
| 已供物品： | 板 |
APPLICATIONS INFORMATION - LOAD ISOLATION EXAMPLE
Considerations for Conversion Efficiency
Converter efficiency is defined as the output power
divided by the input power times 100%.
The losses from the circuit’s front-end components
(leakage across the storage capacitor, comparator, and
R1-R3) will be small (uA) and largely proportional to
the C1 voltage setpoint. Minimizing losses here is
straightforward by appropriate component selection of
C1 and suitably large values of R1 – R3. These small
losses will occur for the entire time that voltage is
present on C1.
The remaining controllable losses will occur in the
step-down converter section and, apart from the
LT1474’s shutdown current, occur only during the ON-
time of the output. The main losses will come from
three sources: V IN current, I 2 R losses, and catch diode
losses.
V IN
The V IN current of the LT1474 is due to two
components: the DC bias current and the gate charge
current of its internal P-channel switch. Both are
proportional to V IN ; however, at load currents > 1mA,
the DC bias current (from 9uA at no load to 100uA in
continuous mode) is negligible compared to the gate
charge losses. Each time the gate is switched on and
off, a packet of charge dQ moves from V IN to ground.
In continuous mode, I GATE = fQp where Qp is the gate
charge of the internal switch and f is the switching
frequency. Since V IN is pre-set according to piezo
efficiency considerations, the best way to minimize this
loss is to keep the output duty cycle low.
Resistive (I 2 R) Losses
The resistances in the current path (The ON-resistance
of the internal switch, current sense resistor, and
inductor) contribute resistive losses. At low values of
V IN , switch losses will dominate, and can be minimized
by using a suitably large inductor and low I PEAK . At
higher supply voltages, these losses are proportional to
load.
Catch Diode Losses
The catch diode, D7, introduces a loss (V*I) as it
conducts during the switch off-time, proportional to its
forward voltage, and more pronounced at high supply
voltage where the switch on-time is shorter. Again, V IN
is fixed for piezo efficiency reasons, so this loss is best
minimized by minimizing the diode V f and converter
duty cycle. By lowering the duty cycle, a reduction in V f
of the catch diode will improve efficiency even though
low-V f diodes tend to have much higher reverse
leakage currents, which will produce loss during the
switch ON-time. In any event, the catch diode must be
sized to safely handle I PEAK at nearly 100% duty cycle
(worst-case condition; output shorted).
The selection of 100uH inductor should be considered
a minimum, for use in conjunction with high I PEAK
values. Particularly in applications where space is not
constrained or I PEAK must be reduced, inductors as
large as 1000uH may be required for maximum
efficiency. The ideal range of inductor size at a given
I MAX is a trade-off between the increased resistance of
higher-value inductors and the increased switching
rates required for lower-value inductors.
At light loads, the output duty cycle will rise and losses
in the conversion stage (leakage, switching and catch
diode losses) will accrue. This may or may not be a
problem; it could simply mean that more power is
available than the load can use.
REVISION N0. 002
REVISION DATE: 01-23-2013
20
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相关代理商/技术参数 |
参数描述 |
|---|---|
| EHEA 1PR | 制造商:Nexans 功能描述:CABLE SCRN 1CORE 7/0.2MM 100M 制造商:NEXANS 功能描述:CABLE, SCRN, 1CORE, 7/0.2MM, 100M 制造商:Nexans 功能描述:SHLD MULTICOND CABLE, 1COND, 24AWG, 328FT, 250V; Reel Length (Imperial):328ft; Reel Length (Metric):100m; No. of Conductors:1; Conductor Size AWG:24AWG; Voltage Rating:250V; No. of Strands x Strand Size:7 x 0.2mm; Cable Type:Shielded;RoHS Compliant: Yes |
| EHEA 2PR BLACK | 制造商:Nexans 功能描述: |
| EHEALTH-GW-SDK | 制造商:Bluegiga Technologies Inc 功能描述:EHEALTH SOFTWARE DEVELOPMENT KIT (SDK) LICENSE* |
| EHF-103-01-F-D | 制造商:Samtec Inc 功能描述:.050 EJECTOR HEADER ASSEMBLY - Bulk |
| EHF-10301-F-D-RA | 制造商:SAMTEC 制造商全称:Samtec, Inc 功能描述:.050 EJECTOR HEADER ASSEMBLY |
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