- 您现在的位置：买卖IC网 > Sheet目录1213 > EHE004 (Mide Technology Corporation)BOARD ENERGY HARVESTING
APPLICATIONS INFORMATION - SWITCHED CAPACITOR BOOST CIRCUIT
R ln o
Goals
Allow intermittently operating circuits to be
powered from extremely weak vibration sources,
C
1
T d
1
V
V
or moderate vibration sources at frequencies sig-
nificantly different from the energy harvester's res-
onant frequency (Figure 3)
Equation 1: Capacitance needed for
a given runtime (F)
Physically disconnect the load during periods of
insufficient voltage to avoid "over-the-hump" prob-
T d
R C ln
V o
V
lems of cold circuit start-up from harvested power
Maximize chances of success where vibration
source's characteristics (amplitude and frequency
Equation 2: Runtime for a given
capacitance (sec.)
content) cannot be known in advance.
W
1
2
C V 0
2
V
2
Simple “One-Shot” Application
A simple usage scenario is an embedded sensor with
Equation 3: Energy per discharge
(Joules or watt-seconds)
data storage/transmission capability, which takes one
set of measurements each time it is powered up
(relying on the loss and subsequent re-application of
P
T c
W
T d
power to start the next measurement). In this case, the
measurement frequency is variable and depends on the
vibration amplitude. To operate the sensor directly from
the boost circuit requires:
Estimation (or measurement of) the run-time and
power consumption of your application within its
voltage limits
Sizing the CP out according to worst-case usage,
allowing some headroom
For such one-shot sensors, it is recommended to
create a large load (e.g. drive an LED or GPIO pin tied
to ground) after completing the task in order to ensure
the power output cycles in high-vibration conditions.
A typical microcontroller sensor application’s load
profile will be “bursty”, complicating the task of
estimating the required value of CP out . However, if the
load can be approximated in terms of a resistive load,
the following equations can be used to estimate the
required capacitance, available runtime, energy per
discharge or power stored.
Equation 4: Average Power (Watts)
In the equations above, T d is the runtime or discharge
time in seconds, T c is the charge time in seconds, R is
the equivalent load resistance in ohms, V 0 is the
starting output voltage (2.4), V is the final output
voltage (1.8V or the minimum operating voltage of the
sensor, whichever is greater), and C is the capacitance
in Farads. Likewise, the output voltage can be modeled
as a simple RC time constant, V = V 0 e -T/RC .
Continuously-Powered Application with
Input-Dependent Triggering
Sometimes it may be advantageous to incorporate
vibration-powered battery maintenance and/or
triggering into a continuously-running circuit. For
example, a sensor may require low-level continuous
power to maintain a realtime clock, but measurement
tasks are only needed when a piece of machinery is
known to be operating. Alternately, it may be desired to
dynamically adjust the measurement rate based on the
incoming power to maintain a given power budget. In
REVISION N0. 002
REVISION DATE: 01-23-2013
15
发布紧急采购，3分钟左右您将得到回复。
相关PDF资料
EHFW2BPKG
CONN EEE1394 FMALE T/H BLK 4-40
EHFWX2X
CONN FIREWIRE FEEDTHROUGH
EHHD15FF
CONN DSUB 15PIN FMAL-FMAL NICKEL
EHLC2M
CONN FIBER OPTIC LC/LC MULT MODE
EHSC2M
CONN FIBER OPTIC ST2 DUAL MODE
EHST2
CONN FIBER OPTIC ST2 SINGLE MODE
EHUSBABBX
CONN USB A FEMALE TO B FEMALE
EHUSBBABX
CONN EH USB B-A BLACK
相关代理商/技术参数
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
EHF-10301-F-D-SM
制造商:SAMTEC 制造商全称:Samtec, Inc 功能描述:.050 EJECTOR HEADER ASSEMBLY
EHF-10301-FM-D-RA
制造商:SAMTEC 制造商全称:Samtec, Inc 功能描述:.050 EJECTOR HEADER ASSEMBLY
EHF-10301-FM-D-SM
制造商:SAMTEC 制造商全称:Samtec, Inc 功能描述:.050 EJECTOR HEADER ASSEMBLY