LM4570LQ

LM4570 Single-Ended Input Motor Driver April 2006 LM4570 Single-Ended Input Motor Driver General Description The LM4570 is a single supply motor driver for improved sensory experience in mobile phones and other handheld devices. The LM4570 is capable of driving up to 192mA while operating from a 3V supply. Near rail-to-rail output swing under load ensures sufficient voltage drive for most DC motors, while the differential output drive allows the voltage polarity across the motor to be reversed quickly. Reversing the voltage gives the LM4570 the ability to drive a motor both clock-wise and counter clock-wise from a single supply. The LM4570 features fast turn on time, and a wide input voltage range for precise speed control. A low power shutdown mode minimizes power consumption. Thermal and output short circuit protection prevents the device from being damaged during fault conditions. Key Specifications j High Output Current @ VDD = 3V j Fast Turn On Time @ 3V j Quiescent Power Supply Current @ 3V j Shutdown Current 192mA 2.4ms 1.9mA 0.1µA (typ) Features n n n n n n n n Output Short Circuit Protection High Output Current Capability Wide Output Voltage Range Fast Turn on Time Output Short Circuit Protection Low Power Shutdown Mode Minimum external components Available in space-saving LLP package Applications n Mobile Phones n PDAs n Video Game Systems Typical Application 20186326 FIGURE 1. Typical Motor Driver Application Circuit © 2006 National Semiconductor Corporation DS201863 www.national.com LM4570 Connection Diagrams Leadless Leadframe Package (LLP) LQ Package 20186325 Top View Order Number LM4570LQ See NS Package Number LQB08A LLP Marking 20186327 Top View X - One digit date code TT - Lot traceability G - Boomer Family C8 - LM4570LQ www.national.com 2 LM4570 Absolute Maximum Ratings (Note 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage (Note 1) Storage Temperature Voltage at Any Input Pin Power Dissipation (Note 3) ESD Susceptibility (Note 4) ESD Susceptibility (Note 5) 6.0V −65˚C to +150˚C −0.3V ≥ to VDD +0.3V Internally Limited 2000V 200V Junction Temperature (TJMAX) Thermal Resistance θJA (LLP) 150˚C 140˚C/W Operating Ratings Temperature Range TMIN ≤ TA ≤ TMAX Supply Voltage −40˚C ≤ TA ≤ 85˚C 2.4V ≤ VDD ≤ 5.5V Electrical Characteristics VDD = 5V (Notes 1, 2) The following specifications apply for VDD = 5V, AV-BTL = 6dB unless otherwise specified. Limits apply for TA = 25˚C. LM4570 Symbol Parameter Conditions VIN = 0V, IL = 0A, No Load VIN = 0V, IL = 0A, RL = 30Ω VSD = GND Typical (Note 6) IDD ISD VIH VIL VOS IOUT TWU VOH VOL Quiescent Power Supply Current Shutdown Current Logic Input High Logic Input Low Output Offset Voltage Output Current Wake-up time Output High Voltage Output Low Voltage RL = 30Ω specified as |VDD - VOH| RL = 30Ω specified as |GND + VOH| VOH, VOL ≤ 250mV 5 268 2.5 146 106 200 200 2.5 2.6 0.1 Limit (Notes 7, 8) 5.5 5.5 1.5 1.4 0.4 Units (Limits) mA (max) µA (max) V (min) V (max) mV (max) mA ms (max) mV (max) mV (max) ± 35 Electrical Characteristics VDD = 3V (Notes 1, 2) The following specifications apply for VDD = 3V, AV-BTL = 6dB unless otherwise specified. Limits apply for TA = 25˚C. LM4570 Symbol Parameter Conditions VIN = 0V, IL = 0A, No Load VIN = 0V, IL = 0A, RL = 30Ω VSD = GND Typical (Note 6) IDD ISD VIH VIL VOS IOUT TWU VOH VOL Quiescent Power Supply Current Shutdown Current Logic Input High Logic Input Low Output Offset Voltage Output Current Wake-up time Output High Voltage Output Low Voltage RL = 30Ω specified as |VDD - VOH| RL = 30Ω specified as |VDD - VOH| VOH, VOL ≤ 200mV 5 192 2.4 90 63 110 110 1.9 1.95 0.1 Limit (Notes 7, 8) 4 4 1.0 1.4 0.4 Units (Limits) mA (max) µA (max) V (min) V (max) mV (max) mA ms (max) mV (max) mV (max) ± 35 3 www.national.com LM4570 Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified. Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is given; however, the typical value is a good indication of device performance. Note 3: The maximum power dissipation must be de-rated at elevated temperatures and is dictated by TJMAX, θJC, and the ambient temperature TA. The maximum allowable power dissipation is PDMAX = (TJMAX –TA)/ θJA or the number given in the Absolute Maximum Ratings, whichever is lower. For the LM4570, TJMAX = 150˚C and the typical θJA for the LLP package is 140˚C/W. Note 4: Human body model, 100pF discharged through a 1.5kΩ resistor. Note 5: Machine Model, 220pF–240pF discharged through all pins. Note 6: Typicals are measured at 25˚C and represent the parametric norm. Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level). Note 8: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis. Note 9: Shutdown current is measured in a normal room environment. Exposure to direct sunlight will increase ISD by a maximum of 2µA. www.national.com 4 LM4570 Typical Performance Characteristics Output Low Voltage vs Load Current VDD = 3V Output Low Voltage vs Load Current VDD = 5V 20186313 20186312 Output High Voltage vs Load Current VDD = 3V Output High Voltage vs Load Current VDD = 5V 20186311 20186310 Output Voltage vs Input Voltage VDD = 3V, RL = 20Ω Output Voltage vs Input Voltage VDD = 3V, RL = 30Ω 20186314 20186315 5 www.national.com LM4570 Typical Performance Characteristics Output Voltage vs Input Voltage VDD = 5V, RL = 20Ω (Continued) Output Voltage vs Input Voltage VDD = 5V, RL = 30Ω 20186316 20186317 Power Dissipation vs Supply Voltage Supply Current vs Supply Voltage 20186320 20186321 Slew Rate vs Supply Voltage RL = 30Ω Shutdown Supply Current vs Supply Voltage 20186319 20186323 www.national.com 6 LM4570 Typical Performance Characteristics Output Transition High to Low, Low to High VDD = 3V, 1V/div, 400ns/div (Continued) Output Transition High to Low, Low to High VDD = 5V, 1V/div, 1µs/div 20186306 20186307 Turn-Off Time VDD = 5V, 2V/div, 1ms/div Turn-On Time VDD = 5V, 2V/div, 1ms/div 20186308 20186309 7 www.national.com LM4570 Application Information BRIDGE CONFIGURATION EXPLANATION The LM4570 uses a bridged architecture that drives a load differentially. The BTL design offers several advantages over a single-ended design. The the device outputs, VO1 and VO2, both source and sink current, which means that the polarity of the voltage across the motor can be reversed quickly (Figure 2). A single-ended device would need to operate from split supplies to achieve this behavior. The ability to reverse the voltage polarity is necessary in applications where a negative (reverse polarity) pulse is used to quickly stop the motor. If the drive voltage is just removed from the motor (not reversed) then the motor will continue to spin until the residual energy stored in the windings has dissipated. The output voltage of the LM4570 is determined by the difference between the input voltage and VREF1 , as well as the differential gain of the device. The output voltage is given by the following: VO1–VO2 = AVD(VIN–VREF1) For input voltages that are less than the reference voltage, the differential output voltage is negative. For input voltages that are greater than the reference voltage, the differential output voltage is positive. For example, when operating from a 5V supply (VREF1 = 2.5V) and with a differential gain of 6dB, with a 1V input, the voltage measured across VO1 and VO2 is -3V, with a 4V input, the differential output voltage is +3V. 20186302 FIGURE 2. Voltage Polarity and Motor Direction www.national.com 8 LM4570 Application Information GAIN SETTING (Continued) The resistors RIN and RF set the gain of the LM4570, given by: VVD = 2 x (RF / RIN) Where AVD is the differential gain. AVD differs from singleended gain by a factor of 2. This doubling is due to the differential output architecture of the LM4570. Driving the load differentially doubles the output voltage compared to a single-ended output amplifier under the same conditions. POWER DISSIPATION The Power Dissipation vs. Supply Voltage graph in the Operating Curves section shows the power dissipation of the LM4570 with the input equal to the supply voltage, meaning the outputs swing rail-to-rail. This configuration results in the output devices of the LM4570 operating in the linear region, essentially very small resistors determined by the RDS(ON) of the output devices. Under these conditions, the power dissipation is dominated by the I*R drop associated with the output current across the RDS(ON) of the output transistors, thus the power dissipation is very low (60mW for a 800mW output). When the input voltage is not equal to GND or VDD, the power dissipation of the LM4570 increases (Figure 3). Under these conditions, the output devices operate in the saturation region, where the devices consume current in addition to the current being steered to the load, increasing the power dissipation. Power dissipation for typical motor driving applications should not be an issue since the most of the time the device outputs will be driven rail-to-rail. 20186328 FIGURE 3. Power Dissipation vs. Input Voltage EXPOSED-DAP MOUNTING CONSIDERATIONS The LM4570 is available in an 8-pin LLP package which features an exposed DAP (die attach paddle). The exposed DAP provides a direct thermal conduction path between the die and the PCB, improving the thermal performance by reducing the thermal resistance of the package. Connect the exposed DAP to GND through a large pad beneath the device, and multiple vias to a large unbroken GND plane. For best thermal performance, connect the DAP pad to a GND plane on an outside layer of the PCB. Connecting the DAP to a plane on an inner layer will result in a higher thermal resistance. Ensure efficient thermal conductivity by plugging and tenting the vias with plating and solder mask, respectively. POWER SUPPLY BYPASSING Good power supply bypassing is critical for proper operation. Locate both the REF1 and VDD bypass capacitors as close to the device as possible. Typical applications employ a regulator with a 10µF tantalum or electrolytic capacitor and a ceramic bypass capacitor which aid in supply stability. This does not eliminate the need for bypass capacitors near the LM4570. Place a 1µF ceramic capacitor as close to VDD as possible. Place a 0.1µF capacitor as close to REF1 as possible. Smaller values of CREF1 may be chosen for decreased turn on times. SHUTDOWN FUNCTION The LM4570 features a low power shutdown mode that disables the device and reduces quiescent current consumption to 0.1µA. Driving /SD Low disables the amplifiers and bias circuitry, and drives VREF1and the outputs to GND. Connect /SD to VDD for normal operation. 9 www.national.com LM4570 Application Information DEMO BOARD LAYOUT (Continued) 20186324 www.national.com 10 LM4570 Revision History Rev 1.0 Date 04/13/06 Description Initial release 11 www.national.com LM4570 Single-Ended Input Motor Driver Physical Dimensions inches (millimeters) unless otherwise noted LLP Package Order Number LM4570LQ NS Package Number LQB08A National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. For the most current product information visit us at www.national.com. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. BANNED SUBSTANCE COMPLIANCE National Semiconductor manufactures products and uses packing materials that meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. Leadfree products are RoHS compliant. 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