QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 630
PIEZOCERAMIC MICROACTUATOR DRIVER WITH BOOST REGULATOR
1
LT3469ETS8
DESCRIPTION
Demonstration circuit 630 is a g
m
amplifier circuit using the
LT
®
3469ETS8 and can drive an output up to 34V at 25mA
from 5V or 12V supply. An internal Boost converter of the
LT3469 generates a supply voltage up to 36V for the g
m
amplifier. This regulator switches at 1.5MHz, allowing the
use of a tiny external inductor and capacitor. The 36V output
capability of the switching regulator along with the high
supply voltage of the amplifier combine to allow the wide
output voltage range needed to drive a piezoceramic
microactuator.
Design files for this circuit board are available. Call the
LTC factory.
LT is a trademark of Linear Technology Corporation
QUICK START PROCEDURE
Demonstration circuit 630 is easy to set up to evaluate the
performance of the LT3469ETS8. Refer to Figure 1 for proper
measurement equipment setup and follow the procedure
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 V
IN
or V
OUT
and GND terminals. See Figure 2 for proper
scope probe technique.
1.
With power off, connect the input power source V
IN
to the
VIN and GND terminals, connect Vinput to INPUT+ and
GND terminals.
2.
Apply V
IN
=4.75V, Vinput=1V, and Iout=0mA (no load).
Check the boost regulator output Vcc=34.8V±5%, and
input current Iin within the range of 21mA to 35mA.
3.
Apply V
IN
=4.75V, Vinput=1V, and Iout=2mA (2mA load at
V
OUT
). Check the boost regulator output Vcc=34.6V±5%,
and the input current Iin within the range of 34mA to
50mA.
4.
Apply V
IN
=16V, Vinput=1V, and Iout=0A (no load). Verify
the boost regulator output Vcc=35.2±5%.
5.
Apply V
IN
=5V, Vinput=0.1V, check the amplifier output
V
OUT
= within the range of 0.87V to 1.12V.
6.
Apply V
IN
=5V, Vinput=3V, check the amplifier output
V
OUT
= 33V±2%,
7.
Apply V
IN
=5V and pulsed square wave input that swings
from 0.1V to 2.8V and has period of 300µs to Vinput, and
apply 27nF capacitor load to the output. Verify V
OUT
and
Iout as shown in Figure 3.
