LT3572EUF#PBF Linear Technology, LT3572EUF#PBF Datasheet - Page 9

• Manufacturer Part Number: LT3572EUF#PBF
• Description: IC DRIVER PIEZO DUAL 20-QFN
• Manufacturer: Linear Technology

Specifications of LT3572EUF#PBF

• Applications: Piezo Motor Driver
• Number Of Outputs: 2
• Voltage - Load: 5 V ~ 40 V
• Voltage - Supply: 2.7 V ~ 10 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -

PWM
The LT3572 can PWM the output drivers at a very high
frequency. The limitation on the frequency is determined
by the internal rise in die temperature that occurs when
driving the motor. The power delivered to the piezo motor
is propotional to V
the PWM frequency. When any of these are increased the
power dissipated in the part increases causing the internal
die temperature to increase. Driving two 2.2nF capacitors
with V
less than 80 kHz. The LT3572 can run at a higher frequency
but either V
needs to be lowered. A piezo motor has an associated
capacitance that cannot be reduced so the output voltage
must be lowered. Since the power is proportional to V
reduction of V
run at a maxim frequency of 115 kHz. If a different motor is
used the maximum PWM frequency will need to be adjusted
inversely to the equivolent capacitance of the motor.
Inductor Selection
A 10μH inductor is recommended for most LT3572 ap-
plications. Choose an inductor that will handle at least
APPLICATIONS INFORMATION
OUT
at 30V, the maximum PWM frequency should be
OUT
OUT
needs to be reduced or the capacitance
to 25V from 30V will allow the LT3572 to
OUT
2
, the capacitance of the motor, and
C3
L1
D1
R4
SYNC
GND
SW
V
RT
IN
1
2
3
4
5
C1
PWMB
OUT
PWMA
OUTA
2
OUTA
V
a
GND
OUT
OUTB
1A without saturating, and ensure that the inductor has a
low DCR (copper-wire resistance) to minimize I
losses. Table 1 lists several inductor manufacturers.
Table 1. Inductor Manufacturers
Sumida
TDK
Murata
FDK
Capacitor Selection
The small size of ceramic capacitors makes them ideal
for LT3572 applications. Only X5R or X7R types should
be used because they retain their capacitance over wider
voltage and temperature ranges than other types such as
Y5V or Z5U. A 4.7μF to 15μF output capacitor is suffi cient
for stable transient response, however, more output ca-
pacitance can help limit the voltage droop on V
transients.
Ceramic capacitors also make a good choice for the input
decoupling capacitor, which should be placed as close as
possible to the LT3572. A 1μF to 4.7μF input capacitor
is suffi cient for most applications. Table 2 shows a list
SHDN
OUTB
15
14
13
12
11
PGOOD
SS
FB
SHDNB
SHDNA
[phone]
[phone]
[phone]
[phone]
C
C2
R2
R1
FF
3572 BD LAYOUT
www.sumida.com
www.tdk.com
www.murata.com
www.tdk.co.jp
LT3572
OUT
2
R power
during
3572fa
9