LT3572
1
DESCRIPTION
Demonstration circuit 1197 features
LT3572 in a 800kHz step-up con-
verter circuit, designed for 30V
output from a 3V to 5V input. The
high output voltage is then used by
the dual full-bridge drivers. The
LT3572 is capable of independently
driving two Piezo motors with two
input PWM signals. The motors re-
spond accordingly based on the duty
cycle and the frequency of the PWM
signals. The drivers operate in an
H-bridge fashion, where the OUTA
and OUTB pins are the same polarity
as the PWMA and PWMB pins respec-
tively and the OUTA and OUTB are
inverted from PWMA and PWMB respec-
tively. A PGOOD pin indicates when
the output of the step-up converter
is in regulation and the Piezo
drivers can start switching. The
step-up converter and both Piezo
drivers have their own shutdown
control.
The LT3572 datasheet gives a com-
plete description of the part, op-
eration and application informa-
tion. The datasheet must be read in
conjunction with this quick start
guide for demo circuit 1197.
Design files for this circuit board
are available. Call the LTC fac-
tory.
, LTC and LT are registered trademarks of Linear Technol-
ogy Corporation. ThinSOT and PowerPath are trademarks of Lin-
ear Technology Corporation.
Performance Summary for Piezo Driver ( TA = 25oC )
PARAMETER CONDITION VALUE
Minimum Input Voltage 3V
Maximum Input Voltage 5V (Note 1)
Output Voltage VOUT 30V +/-3%
Typical Load 2 TULA50 Piezo Motors
Typical Switching Frequency 800kHz
Note 1: Maximum input voltage of the demo circuit is limited by the voltage rating of the input
capacitor.
DEMO CIRCUIT 119
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QUICK START GUID
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LT357
2
Dual Full-Bridge Piezo Drive
r
With 900mA Boost Converte
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LT3572
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QUICK START PROCEDURE
Demonstration circuit 1197 is easy
to set up to evaluate the perform-
ance of the LT3572. Refer to
Figure 1 for proper measurement
equipment setup and follow the pro-
cedure below:
NOTE.
When measuring the input or
output voltage ripple, care must be
taken to avoid a long ground lead
on the oscilloscope probe. Measure
the input or output voltage ripple
by touching the probe tip directly
across the Vin or Vout and GND ter-
minals. See Figure 2 for proper
scope probe technique.
1. Place JP3, JP4 and JP5 on the
ON position:
2. Connect the two TULA50 Piezo
Motors to JP1 and JP2.
3. With power off, connect the in-
put power supply to Vin and GND.
4. Turn on the power at the input.
NOTE.
Make sure that the input
voltage does not exceed the maxi-
mum input voltage.
5. Check for the proper output
voltage.
6. Apply PWM signals, typically
switching between 0V and 2V, to
the PWMA and PWMB pins.
7. Adjust the duty cycles of the
input PWM signals and observe
the movement of the motors.
LT3572
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Figure 1. Proper Measurement Equipment Setup
VIN
GND
Figure 2. Measuring Input or Output Ripple
LT3572
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