LINEAR TECHNOLOGY LT3572 Technical data

LT3572

Dual Full-Bridge Piezo Driver

with 900mA Boost Converter

FEATURES

■

2.7V to 10V Input Voltage Range

■

900mA Boost Converter

■

Dual Full-Bridge Piezo Drivers

■

Programmable Switching Frequency from

500kHz to 2.25MHz

■

Synchronizable Up to 2.5MHz

■

Soft-Start

■

Separate Enable for Each Piezo Driver and Boost

Converter

■

Available in a 4mm × 4mm 20-Pin QFN Package

APPLICATIONS

■

Piezo Motor Drive

TYPICAL APPLICATION

DESCRIPTION

The LT®3572 is a highly integrated dual Piezo motor driver
capable of driving two Piezo motors at up to 40V from a
5V supply. Each Piezo driver can be independently turned
on or off along with the boost converter.

The boost regulator has a soft-start capability that limits the
inrush current at start-up. The boost regulator switching
frequency is set by an external resistor or the frequency can
be synchronized by an external clock. A PGOOD pin indicates
when the output of the boost converter is in regulation and
the Piezo drivers are allowed to start switching.

The LT3572 is available in a (4mm × 4mm) 20-pin QFN
package.

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.

V

3V TO 5V

Dual Piezo Driver

SHDN
SHDNA
SHDNB
PWMA
PWMB
SYNC
PGOOD

RT

SS

10nF

10μH

15pF

V

SW

GND

V

OUT

OUTA

OUTA

OUTB

OUTB

FB

IN

LT3572

576k

24.3k

IN

100k

4.7μF

42.2k

V
30V
50mA

10μF

3572 TA01a

OUT

Response Driving Piezo Motor at 70kHz

V

OUTA

20V/DIV

V

OUTA

20V/DIV

PWMA
2V/DIV

2μs/DIV

3572 TA01b

3572fa

1

LT3572

ABSOLUTE MAXIMUM RATINGS

(Note 1)

V

Voltage .............................................................40V

OUT

OUTA, OUTA, OUTB, OUTB Voltage ...........................40V

SW Voltage ...............................................................42V

RT, SS, SYNC ..............................................................2V

FB ............................................................................... 3V

All Other Pins ............................................................10V

Maximum Junction Temperature........................... 125°C

Operating Temperature Range (Note 2).... –40°C to 85°C

Storage Temperature Range ...................–65°C to 125°C

ORDER INFORMATION

PIN CONFIGURATION

TOP VIEW

GND

OUTA

OUTA

OUTB

20 19 18 17 16

1

SW

V

2

IN

SYNC

3

RT

4

GND

5

20-LEAD (4mm s 4mm) PLASTIC QFN

T

EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB

JMAX

21

6 7 8

PWMB

= 125°C, θJA = 37°C/W

OUT

V

PWMA

UF PACKAGE

9 10

GND

OUTB

SHDN

PGOOD

15

SS

14

FB

13

SHDNB

12

SHDNA

11

LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE

LT3572EUF#PBF LT3572EUF#TRPBF 3572 20-Lead (4mm × 4mm) Plastic DFN –40°C to 85°C

Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based fi nish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to: http://www.linear.com/tapeandreel/

ELECTRICAL CHARACTERISTICS

The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C. VIN = 5V, V

SHDNA

= V

SHDNB

= V

5V, unless otherwise noted.

SHDN =

PARAMETER CONDITIONS MIN TYP MAX UNITS

Minimum Operating Voltage

Quiescent Current VFB = 1.3V 3.4 4 mA

V

IN

Shutdown Current V

V

IN

SHDN

= V

SHDNA

= V

= 0V 0 1 μA

SHDNB

●

2.5 2.7 V

SHDN Pin Threshold 0.3 1.5 V
SHDNA Pin Threshold 0.3 1.5 V
SHDNB Pin Threshold 0.3 1.5 V
SHDN Pin Bias Current V

SHDNA Pin Bias Current V

SHDNB Pin Bias Current V

V

V

V

SHDN
SHDN

SHDN
SHDN

SHDN
SHDN

= 5V, V
= 0V, V

= 0V, V
= 0V, V

= 0V, V
= 0V, V

SHDNA
SHDNA

SHDNA
SHDNA

SHDNA

SHDNA

= 0V, V
= 0V, V

= 5V, V
= 0V, V

= 0V, V

= 0V, V

SHDNB
SHDNB

SHDNB
SHDNB

SHDNB

SHDNB

= 0V
= 0V

= 0V
= 0V

= 5V

= 0V

8

0.1

8

0.1

8

0.1

15

15

15

1

μA

μA

μA

1

μA

μA

1

μA

2

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LT3572

ELECTRICAL CHARACTERISTICS

The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T

PARAMETER CONDITIONS MIN TYP MAX UNITS

PWMA Pin Threshold 0.3 1.5 V

PWMB Pin Threshold 0.3 1.5 V

PGOOD Rising Threshold (Note 3)
PGOOD Falling Threshold (Note 4)
PGOOD Resistance

Switching Frequency RT = 75.0kΩ

Maximum Duty Cycle RT = 75.0kΩ

Synchronization Frequency 575 2500 kHz

SYNC Pin Thresholds (Note 5) 0.3 1.5 V

SS Current 4.5 μA

FB Pin Voltage

FB Pin Voltage Line Regulation V

FB Pin Bias Current V

SW Current Limit (Note 7) 0.9 1.3 1.7 A

SW V

CESAT

SW Leakage Current SW = 40V 0.2 5 μA

OUTx Rise Time C = 2.2nF, V

OUTx Fall Time C = 2.2nF, V

= 25°C. VIN = 5V, V

A

RT = 13.0kΩ

RT = 13.0kΩ

= 2.5V to 10V 0.01 0.05 %/V

IN

= 1.225V (Note 6) 50 200 nA

FB

ISW = 800mA 310 450 mV

= 30V (Note 8) 120 ns

OUT

= 30V (Note 8) 120 ns

OUT

SHDNA

= V

SHDNB

= V

5V, unless otherwise noted.

SHDN =

●

1.12 1.16 1.19 V

●

1.01 1.04 1.065 V

●

●

425

●

1.9

●

95

●

85

●

1.195 1.225 1.255 V

500

2.25

13 kΩ

575

2.6

kHz

MHz

%
%

Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.

Note 2: The LT3572 is guaranteed to meet specifi ed performance from
0°C to 70°C operating junction temperature. Specifi cations over the
–40°C to 85°C operating junction temperature range are assured by
design, characterization and correlation with statistical process controls.

Note 3: Rising threshold voltage on FB pin that pulls PGOOD low.
Note 4: Falling threshold voltage on FB pin that causes a high impedance

on PGOOD.

Note 5: Minimum pulse width is 100ns. Maximum off pulse width is 100ns.
Note 6: Current fl ows into the pin.
Note 7: Current limit guaranteed by design and/or correlation to static test.
Note 8: OUTx refers to OUTA, OUTA, OUTB, OUTB.

3572fa

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LT3572

TYPICAL PERFORMANCE CHARACTERISTICS

Feedback Pin Voltage vs
Temperature

1.25

1.24

1.23

1.22

FEEDBACK VOLTAGE (V)

1.21

1.20
–50

–25 0

25 75 150

TEMPERATURE (°C)

50

100 125

3572 G01

Oscillator Frequency vs
Temperature

2.5

2.0

1.5

1.0

FREQUENCY (MHz)

0.5

0

–50

–25 0

25 75 150

TEMPERATURE (°C)

RT = 13k

RT = 35k

50

Quiescent Current vs Temperature SHDN Pin Current vs Temperature

4.0

3.5

3.0

2.5

2.0

1.5

1.0

QUIESCENT CURRENT (mA)

0.5

0

–25

–50

0

25

TEMPERATURE (°C)

50

75

100

125

150

3572 G04

10

9

8

7

6

5

4

3

SHDN PIN CURRENT (μA)

2

1

0

–50

–25 25

0

TEMPERATURE (°C)

V

V

SHDN

SHDN

= 5V

= 2.5V

50

75

100 125

125

100

3572 G02

3572 G05

150

SS Pin Current vs Temperature

8

7

6

5

4

3

SS PIN CURRENT (μA)

2

1

0

–25

–50

0

50

25

TEMPERATURE (°C)

75

SW Current Limit vs Temperature

1.6

1.4

1.2

1.0

0.8

0.6

PEAK CURRENT (A)

0.4

0.2

0

–25

–50

0

50

25

TEMPERATURE (°C)

75

100

100

125

125

150

3572 G03

150

3572 G06

4

SW Saturation Voltage vs
Temperature

0.50

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

SWITCH SATURATION VOLTAGE (V)

0.05

0

–50

–25 25

ISW = 800mA

ISW = 400mA

0

50

TEMPERATURE (°C)

Start-Up

I

IN

200mA/DIV

V

OUT

20V/DIV

V

OUTA

20V/DIV

PGOOD

5V/DIV

200μs/DIV

125

100

75

150

3572 G07

3572 G08

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