3572

LT3572 LINER

Document overview

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Technical content

FEATURES

APPLICATIONS

DESCRIPTION

Dual Full-Bridge Piezo Driver with 900mA Boost Converter 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. Dual Piezo Driver ■ 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 ■ Piezo Motor Drive , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. SHDN SHDNA SHDNB PWMA PWMB SYNC PGOOD RT SS V IN VIN 3V TO 5V SW 10μH GND L T3572 10nF 4.7μF 15pF 10μF VOUT 30V 50mA 100k 576k 24.3k

3572 TA01a

OUTB42.2k VOUT Response Driving Piezo Motor at 70kHz VOUTA 20V/DIV VOUTA 20V/DIV PWMA 2V/DIV 2μs/DIV

3572 TA01b

PIN CONFIGURATIONABSOLUTE MAXIMUM RATINGS Operating Temperature Range (Note 2).... –40°C to 85°C (Note 1) 20 19 18 17 16 6 7 8 TOP VIEW UF PACKAGE 20-LEAD (4mm s 4mm) PLASTIC QFN 9 10 15SW VIN SYNC RT GND PGOOD SS FB SHDNB SHDNA GND OUTA OUTA OUTB OUTB PWMB PWMA V OUT GND SHDN TJMAX = 125°C, θJA = 37°C/W EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION

ELECTRICAL CHARACTERISTICS

PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Operating Voltage ● 2.5 2.7 V VIN Quiescent Current VFB = 1.3V 3.4 4 mA VIN Shutdown Current VSHDN = VSHDNA = VSHDNB = 0V 0 1 μA 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 VSHDN = 5V, VSHDNA = 0V, VSHDNB = 0V VSHDN = 0V, VSHDNA = 0V, VSHDNB = 0V 0.1 μA μA SHDNA Pin Bias Current VSHDN = 0V, VSHDNA = 5V, VSHDNB = 0V VSHDN = 0V, VSHDNA = 0V, VSHDNB = 0V 0.1 μA μA SHDNB Pin Bias Current V SHDN = 0V, VSHDNA = 0V, VSHDNB = 5V VSHDN= 0V, VSHDNA = 0V, VSHDNB = 0V 0.1 μA μA The ● denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = 5V, VSHDNA= VSHDNB = VSHDN = 5V, unless otherwise noted. 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/

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. 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, VSHDNA= VSHDNB = VSHDN = 5V, unless otherwise noted. 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) ● 1.12 1.16 1.19 V PGOOD Falling Threshold (Note 4) ● 1.01 1.04 1.065 V PGOOD Resistance ● 13 k Ω Switching Frequency RT = 75.0k Ω RT = 13.0kΩ 425 1.9 500 2.25 575 2.6 kHz MHz Maximum Duty Cycle RT = 75.0k Ω RT = 13.0kΩ Synchronization Frequency 575 2500 kHz SYNC Pin Thresholds (Note 5) 0.3 1.5 V SS Current 4.5 μA FB Pin Voltage

• 1.195 1.225 1.255 V FB Pin Voltage Line Regulation V IN = 2.5V to 10V 0.01 0.05 %/V FB Pin Bias Current V FB = 1.225V (Note 6) 50 200 nA SW Current Limit (Note 7) 0.9 1.3 1.7 A SW V CESAT ISW = 800mA 310 450 mV SW Leakage Current SW = 40V 0.2 5 μA OUTx Rise Time C = 2.2nF, V OUT = 30V (Note 8) 120 ns OUTx Fall Time C = 2.2nF, V OUT = 30V (Note 8) 120 ns 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.

TYPICAL PERFORMANCE CHARACTERISTICS Feedback Pin Voltage vs Temperature Oscillator Frequency vs Temperature SS Pin Current vs Temperature Quiescent Current vs Temperature SHDN Pin Current vs Temperature SW Current Limit vs Temperature SW Saturation Voltage vs Temperature Start-Up TEMPERATURE (°C) –50 FEEDBACK VOL TAGE (V) 1.23 1.24 1.25 25 75 150

3572 G01

1.22 1.21 1.20 –25 0 50 100 125 TEMPERATURE (°C) –50 FREQUENCY (MHz) 1.5 2.0 2.5 25 75 150

3572 G02

1.0 0.5 –25 0 50 100 125 RT = 13k RT = 35k TEMPERATURE (°C) –50 SS PIN CURRENT (μA) 150

3572 G03

0 50 100–25 25 75 125 TEMPERATURE (°C) –50 QUIESCENT CURRENT (mA) 2.0 3.0 150

3572 G04

1.0 0 50 100–25 25 75 125 4.0 1.5 2.5 0.5 3.5 TEMPERATURE (°C) –50 SHDN PIN CURRENT (μA) 0 50 75

3572 G05

–25 25 100 125 150 VSHDN = 5V VSHDN = 2.5V TEMPERATURE (°C) –50 PEAK CURRENT (A) 0.8 1.2 150

3572 G06

0.4 0 50 100–25 25 75 125 1.6 0.6 1.0 0.2 1.4 TEMPERATURE (°C) –50 SWITCH SATURATION VOLTAGE (V)0.05 0.15 0.20 0.25 0.50 0.35 0 50 75

3572 G07

0.10 0.40 0.45 0.30 –25 25 100 125 150 ISW = 800mA ISW = 400mA IIN 200mA/DIV VOUT 20V/DIV VOUTA 20V/DIV PGOOD 5V/DIV 200μs/DIV 3572 G08

SW (Pin 1): Switch Node. This pin connects to the col- lector of an internal NPN power switch. VIN (Pin 2): Input Supply Pin. This pin must be locally bypassed with a capacitor. SYNC (Pin 3): Synchronization Pin. This pin is used to synchronize the internal oscillator to an external signal. The synchronizing range is 15% above the free running frequency set by the RT pin up to 2.5MHz. If not used, this pin must be tied to GND. RT (Pin 4): Frequency Set Pin. Place a resistor to GND to set the internal frequency. The range of oscillation is 500kHz to 2.25MHz. GND (Pins 5, 9, 20): Ground. PWMB (Pin 6): Logic Input for the Driver. A high signal on this input sets OUTB high and OUTB low. PWMA (Pin 7): Logic Input for the Driver. A high signal on this input sets OUTA high and OUTA low. V OUT (Pin 8): Output for the Switching Regulator and the Input Supply for the Drivers. SHDN (Pin 10): Shutdown Pin. Tie to 1.5V or more to enable the switcher. Pull low to disable the switcher. SHDNA (Pin 11): Shutdown Pin. Tie to 1.5V or more to enable OUTA and OUTA. Pull low to place OUTA and OUTA in a high impedance state. SHDNB (Pin 12): Shutdown Pin. Tie to 1.5V or more to enable OUTB and OUTB. Pull low to place OUTB and OUTB in a high impedance state. FB (Pin 13): Feedback Pin. The LT3572 regulates this pin to 1.225V. Connect the feedback resistors to this pin to set the output voltage for the switching regulator. SS (Pin 14): Soft-Start Pin. Place a soft-start capacitor here. A capacitor on the soft-start pin slowly ramps the current limit of the part from 0A to 1.3A. PGOOD (Pin 15): This pin is an open-drain output that pulls low when the FB pin is within 95% of its regulation value. OUTB (Pin 16): The Output Driver. This node switches between V OUT and GND and is inverted from OUTB. OUTB (Pin 17): The Output Driver. This node switches between VOUT and GND. OUTA (Pin 18): The Output Driver. This node switches between VOUT and GND . OUTA (Pin 19): The Output Driver. This node switches between VOUT and GND and is inverted from OUTA. Exposed Pad (Pin 21): Ground. The Exposed Pad of the package provides both electrical contact to ground and good thermal contact to the printed circuit board. The Exposed Pad must be soldered to the circuit board for proper operation.

19 OUTA

17 OUTB

3572 F01

Figure 1. Block Diagram

The LT3572 uses a constant frequency, current mode, control scheme to provide excellent line and load regulation for the output drivers. Operation can be best understood by referring to the Block Diagram in Figure 1. A pulse from the oscillator sets the RS fl ip-fl op, A4, and turns on the internal NPN bipolar power switch, Q1. Current in Q1 and the external inductor, L1, begins to increase. When this current exceeds a level determined by the voltage at the output of the error amplifi er A1, comparator A2 resets A4, turning Q1 off. The current in L1 fl ows through the external Schottky diode D1 and begins to decrease. The cycle begins again at the next pulse from the oscillator. In this way, the voltage at the output of the error amplifi er controls the current through the indictor to the output. The soft-start capacitor, C2, clamps the output of the error amplifi er causing the current limit to slowly increase. This helps reduce overshoot on the output and helps minimize inrush current on the input. Output Drivers The function of the driver section is to level shift the input of the PWM pins to the voltage of the V OUT pin. The drivers operate in an H-bridge fashion, where the OUTA and OUTB pins are the same polarity as the PWMA and PWMB pins respectively and the OUTA and OUTB are inverted from PWMA and PWMB respectively. The OUT pins will be high impedance until the FB pin is within 95% of its regulated voltage. The OUT pins will follow PWMA and PWMB as long as FB stays within 85% of the regulated voltage. If FB drops below 85%, the OUT pins will go high impedance.

drawn from the supply during start-up. Figure 2. RT Resistance vs Switching Frequency

3572 F02

inversely to the equivolent capacitance of the motor. losses. Table 1 lists several inductor manufacturers. Table 1. Inductor Manufacturers

3572 BD LAYOUT

3572 TA02

Table 2. Ceramic Capacitor Manufacturers A Schottky diode is recommended for use with the LT3572. paid to the PCB board layout and component placement. as short as possible. Note the vias under the Exposed Pad.

Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. PACKAGE DESCRIPTION 20-Lead Plastic QFN (4mm × 4mm) (Reference LTC DWG # 05-08-1710 Rev A) 4.00 p 0.10 4.00 p 0.10 NOTE: 1. DRAWING IS PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGGD-1)—TO BE APPROVED 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE PIN 1 TOP MARK (NOTE 6) 0.40 p 0.10 2019 BOTTOM VIEW—EXPOSED PAD

2.00 REF

2.45 p 0.10 0.75 p 0.05 R = 0.115 TYP R = 0.05 TYP 0.25 p 0.05

0.50 BSC

0.200 REF

0.00 – 0.05 (UF20) QFN 01-07 REV A RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 0.70 p0.05 0.25 p0.05 2.00 REF 2.45 p 0.05 3.10 p 0.05 4.50 p 0.05 PACKAGE OUTLINE PIN 1 NOTCH R = 0.20 TYP OR 0.35 s 45o CHAMFER 2.45 p 0.10 2.45 p 0.05

Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2007 LT 0408 REV A • PRINTED IN USA RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1160 Half-/Full-Bridge N-Channel MOSFET Driver V IN: 10V to 15V, VOUT(MAX) = 60V, 24-Lead SO Package LT3469 Piezo Microactuator Driver with Boost Regulator V IN: 2.5V to 16V, VOUT = 35V Maximum, 40mA Current Limit for Piezo Microactuator LT3479 3A, Full Featured DC/DC Converter with Soft-Start and Inrush Current Protection VIN: 2.5V to 24V, VOUT(MAX) = 40V, IQ = Analog/PWM, ISD < 1μA, DFN, TSSOP Packages LT3580 42V, 2A, 2.5MHz High Effi ciency Step-Up DC/DC Converter V IN: 2.5V to 32V, VOUT(MAX) = 40V, IQ = 1mA, ISD < 1μA, 3mm × 3mm DFN8 and MS8E Packages