V25W Mide Technology Corporation, V25W Datasheet - Page 22

• Manufacturer Part Number: V25W
• Description: PIEZOELECTRIC ENERGY HARVESTER
• Manufacturer: Mide Technology Corporation
• Series: Volture™r

Specifications of V25W

• Sensor Type: Acceleration
• Sensing Range: 60Hz ~ 140Hz
• Output Type: Analog
• Operating Temperature: -40°C ~ 90°C
• Features: Piezoelectric Vibration Energy Harvesting, Hermetically Sealed
• Package / Case: Cantilever Piezo Film (Wafer)
• Mounting Type: Through Hole
• Termination: PC Pins
• Lead Free Status / RoHS Status: Lead free by exemption / RoHS compliant by exemption

APPLICATIONS INFORMATION -
as the comparator will be ON when approaching this
point. Solving for R3,
The addition of R3 will slightly affect the actual center
voltage; however, this change will typically not be
significant in comparison with the size of the hysteresis
band. For a typical V
be lowered. As indicated by Figure 5, however, driving
the piezo to moderately higher open-circuit voltages
than optimal does not have an excessive impact on
efficiency.
Check: Actual V
Once all resistor values are chosen, the actual upper
and lower trip points will be defined by:
R3
V
V
h
h
R1 Vth R2 Vth R2 VL
l
and V
1.182
1.182
c
R1 R2 VL Vth
(>3.3V), the final value of V
l
R1 R3 R2
R2 R3 R1
R2 R3
R2
REVISION N0. 001
LOAD ISOLATION EXAMPLE
c
will
REVISION DATE: 06-03-2010
Latch-Up Consideration
If diode D8 is removed, the designer must pay attention
to D6, which is necessary to prevent latch-up of the
LT1474’s output switch if the voltage at its SW pin is
held up while V
occur in an application where the load is powered by
multiple sources or includes a storage element, such
as supercapacitor or battery, whose voltage drops
more slowly than that of C1 when no harvested power
is available. The user must then choose D6 so that the
voltage at SW cannot exceed the voltage at V
0.6V required for latch-up. Particularly at high C1
voltages, the designer must also take steps to ensure
that reverse leakage over D6 will not allow the voltages
at the V
ratings at no load.
FB
and SW pins to float above their maximum
IN
drops. This situation may easily
IN
by the
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