MP1584数据手册(MP1584).pdf-资料库

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MP1584 3A, 1.5MHz, 28V Step-Down Converter FEATURES  Wide 4.5V to 28V Operating Input Range  Programmable Switching Frequency from 100kHz to 1.5MHz  High-Efficiency Pulse Skipping Mode for Light Load  Ceramic Capacitor Stable   Internal Soft-Start Internally Set Current Limit without a Current Sensing Resistor  Available in SOIC8E Package. APPLICATIONS  High Voltage Power Conversion  Automotive Systems   Distributed Power Systems  Battery Powered Systems “MPS” and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. Industrial Power Systems The Future of Analog IC Technology DESCRIPTION The MP1584 is a high frequency step-down switching regulator with an integrated internal high-side high voltage power MOSFET. It provides 3A output with current mode control for fast loop response and easy compensation. The wide 4.5V to 28V input range accommodates a variety of step-down applications, including those in an automotive input environment. A 100µA operational quiescent current allows use in battery-powered applications. High power conversion efficiency over a wide load range is achieved by scaling down the switching frequency at light load condition to reduce the switching and gate driving losses. The frequency foldback helps prevent inductor thermal current runaway during startup and shutdown provides fault tolerant operation. By switching at 1.5MHz, the MP1584 is able to prevent EMI (Electromagnetic Interference) noise problems, such as those found in AM radio and ADSL applications. The MP1584 is available in a thermally enhanced SOIC8E package. reliable, TYPICAL APPLICATION C4 100nF SW FB 8 BST MP1584 VIN EN FREQ COMP GND 5 1 4 3 7 2 6 D1 C3 220pF C6 NS VOUT 3.3V ) % ( I Y C N E C F F E I Efficiency Curve (fSW=500kHz) 100 90 80 70 60 50 40 30 20 10 0 0.01 VIN=12V VIN=24V 0.1 1 OUTPUT CURRENT (A) 10 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. www.MonolithicPower.com © 2011 MPS. All Rights Reserved. VIN EN MP1584 Rev. 1.0 8/8/2011 1

MP1584 – 3A, 1.5MHz, 28V STEP-DOWN CONVERTER ORDERING INFORMATION Part Number* MP1584EN Package SOIC8E Top Marking MP1584EN Free Air Temperature (TA) –20C to +85C * For Tape & Reel, add suffix –Z (e.g. MP1584EN–Z); For RoHS Compliant Packaging, add suffix –LF. (e.g. MP1584EN–LF–Z) PACKAGE REFERENCE TOP VIEW SW EN COMP FB 1 2 3 4 8 7 6 5 BST VIN FREQ GND ABSOLUTE MAXIMUM RATINGS (1) Supply Voltage (VIN) ..................... –0.3V to +30V Switch Voltage (VSW) ............ –0.3V to VIN + 0.3V BST to SW ..................................... –0.3V to +6V All Other Pins ................................. –0.3V to +6V Continuous Power Dissipation (TA = +25°C)(2) ............................................................. 2.5W Junction Temperature ............................... 150C Lead Temperature .................................... 260C Storage Temperature .............. –65°C to +150C Recommended Operating Conditions (3) Supply Voltage VIN ........................... 4.5V to 28V Output Voltage VOUT ......................... 0.8V to 25V Operating Junct. Temp (TJ) ..... –20C to +125C Thermal Resistance (4) SOIC8E .................................. 50 ...... 10 ... C/W θJC θJA Notes: 1) Exceeding these ratings may damage the device. 2) The maximum allowable power dissipation is a function of the maximum junction temperature TJ(MAX), the junction-to- ambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD(MAX)=(TJ(MAX)- TA)/ θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. 3) The device is not guaranteed to function outside of its operating conditions. 4) Measured on JESD51-7, 4-layer PCB. MP1584 Rev. 1.0 8/8/2011 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. www.MonolithicPower.com © 2011 MPS. All Rights Reserved. 2

MP1584 – 3A, 1.5MHz, 28V STEP-DOWN CONVERTER GCS VFB 4.5V < VIN < 28V RDS(ON) VBST – VSW = 5V Symbol Condition VEN = 0V, VSW = 0V, VIN = 28V ELECTRICAL CHARACTERISTICS VIN = 12V, VEN = 2.5V, VCOMP = 1.4V, TA= +25C, unless otherwise noted. Parameter Feedback Voltage Upper Switch On Resistance Upper Switch Leakage Current Limit COMP to Current Sense Transconductance Error Amp Voltage Gain (5) Error Amp Transconductance Error Amp Min Source current Error Amp Min Sink current VIN UVLO Threshold VIN UVLO Hysteresis Soft-Start Time (5) Oscillator Frequency Shutdown Supply Current Quiescent Supply Current Thermal Shutdown Thermal Shutdown Hysteresis Minimum Off Time (5) Minimum On Time (5) EN Up Threshold EN Hysteresis Note: 5) Guaranteed by design. ICOMP = ±3µA VFB = 0.7V VFB = 0.9V 0V < VFB < 0.8V RFREQ = 100kΩ VEN = 0V No load, VFB = 0.9V Min 0.776 4.0 40 2.7 1.35 MP1584 Rev. 1.0 8/8/2011 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. www.MonolithicPower.com © 2011 MPS. All Rights Reserved. 0.824 Typ Max Units V 0.8 mΩ 150 μA 1 4.7 A 9 200 60 5 –5 3.0 0.35 1.5 900 12 100 150 15 100 100 1.5 300 80 3.3 20 125 1.65 A/V V/V µA/V µA µA V V ms kHz µA µA C C ns ns V mV 3

MP1584 – 3A, 1.5MHz, 28V STEP-DOWN CONVERTER PIN FUNCTIONS SOIC Pin # Name Description 1 SW 2 3 4 5 6 7 8 Switch Node. This is the output from the high-side switch. A low forward drop Schottky diode to ground is required. The diode must be close to the SW pins to reduce switching spikes. Enable Input. Pulling this pin below the specified threshold shuts the chip down. Pulling it up above the specified threshold or leaving it floating enables the chip. EN COMP Compensation. This node is the output of the error amplifier. Control loop frequency compensation is applied to this pin. Feedback. This is the input to the error amplifier. The output voltage is set by a resistive divider connected between the output and GND which scales down VOUT equal to the internal +0.8V reference. FB GND Exposed Ground. It should be connected as close as possible to the output capacitor to shorten the high current switch paths. Connect exposed pad to GND plane for optimal thermal performance. Pad FREQ Switching Frequency Program Input. Connect a resistor from this pin to ground to set the switching frequency. Input Supply. This supplies power to all the internal control circuitry, both BS regulators and the high-side switch. A decoupling capacitor to ground must be placed close to this pin to minimize switching spikes. VIN BST Bootstrap. This is the positive power supply for the internal floating high-side MOSFET driver. Connect a bypass capacitor between this pin and SW pin. MP1584 Rev. 1.0 8/8/2011 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. www.MonolithicPower.com © 2011 MPS. All Rights Reserved. 4

MP1584 – 3A, 1.5MHz, 28V STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS VIN = 12V, VOUT=5V, C1 = 10µF, C2 = 22µF, L1= 10µH, TA = +25C, unless otherwise noted. Oscillating Frequency vs. Rfreq ) Z H k ( Y C N E U Q E R F G N T A L L C S O I I 1600 1400 1200 1000 800 600 400 200 0 10 100 1000 10000 Steady State IOUT=0.1A, fSW=500kHz Steady State IOUT=1A, fSW=500kHz Steady State IOUT=2A, fSW=500kHz VOUT AC Coupled 10mV/div. VSW 10V/div. IL 1A/div. 1 v. VOUT AC Coupled 10mV/div. VSW 10V/div. IL 1A/div. VOUT AC Coupled 10mV/div. VSW 10V/div. IL 2A/div. 2 v. 2 v. MP1584 Rev. 1.0 8/8/2011 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. www.MonolithicPower.com © 2011 MPS. All Rights Reserved. 5

MP1584 – 3A, 1.5MHz, 28V STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 12V, C1 = 10µF, C2 = 22µF, L1 = 10µH, fSW=500kHz, and TA = +25C, unless otherwise noted. Startup IOUT = 0.1A Shutdown IOUT = 0.1A Startup IOUT = 1A VEN 5V/div. VOUT 2V/div. VSW 10V/div. IL 1A/div. VEN 5V/div. VOUT 2V/div. VSW 10V/div. IL 1A/div. VOUT 2V/div. IL 1A/div. VEN 5V/div. VOUT 2V/div. VSW 10V/div. IL 1A/div. VEN 5V/div. VOUT 2V/div. VSW 10V/div. IL 1A/div. 5ms/div. 1ms/div. 5ms/div. Shutdown IOUT = 1A Startup IOUT = 2A Shutdown IOUT = 2A VEN 5V/div. VOUT 2V/div. VSW 10V/div. IL 2A/div. 5ms/div. VEN 5V/div. VOUT 2V/div. VSW 10V/div. IL 2A/div. Short Circuit Entry IOUT = 0.1A to Short Short Circuit Recovery IOUT = Short to 0.1A VOUT 2V/div. IL 1A/div. MP1584 Rev. 1.0 8/8/2011 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. www.MonolithicPower.com © 2011 MPS. All Rights Reserved. 6

BLOCK DIAGRAM MP1584 – 3A, 1.5MHz, 28V STEP-DOWN CONVERTER VIN VIN EN VOUT FB REFERENCE UVLO/ THERMAL SHUTDOWN INTERNAL REGULATORS + -- --+ 5V 2.6V SW 1.5ms SS SS Gm Error Amp SS 0V8 -- + ISW -- + Level Shift COMP OSCILLATOR CLK BST SW ISW COMP GND FREQ Figure 1—Functional Block Diagram VOUT is a variable step-down OPERATION frequency, The MP1584 non-synchronous, switching regulator with an integrated high-side high voltage power MOSFET. It provides a highly efficient solution with current mode control for fast loop response and easy compensation. It features a wide input voltage range, internal soft-start control and precision current limiting. low operational quiescent current Its very makes it suitable for battery powered applications. PWM Control At moderate to high output current, the MP1584 operates in a fixed frequency, peak current control mode to regulate the output voltage. A PWM cycle is initiated by the internal clock. The power MOSFET is turned on and remains on until its current reaches the value set by the COMP voltage. When the power switch is off, it remains off for at least 100ns before the next cycle starts. If, in one PWM period, the current in the power MOSFET does not reach the COMP set current value, the power MOSFET remains on, saving a turn-off operation. MP1584 Rev. 1.0 8/8/2011 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. www.MonolithicPower.com © 2011 MPS. All Rights Reserved. 7

MP1584 – 3A, 1.5MHz, 28V STEP-DOWN CONVERTER Error Amplifier The error amplifier compares the FB pin voltage with the internal reference (REF) and outputs a current proportional to the difference between the two. This output current is then used to charge the external compensation network to form the COMP voltage, which is used to control the power MOSFET current. During operation, the minimum COMP voltage is clamped to 0.9V and its maximum is clamped to 2.0V. COMP is internally pulled down to GND in shutdown mode. COMP should not be pulled up beyond 2.6V. Internal Regulator Most of the internal circuitries are powered from the 2.6V internal regulator. This regulator takes the VIN input and operates in the full VIN range. When VIN is greater than 3.0V, the output of the regulator is in full regulation. When VIN is lower than 3.0V, the output decreases. Enable Control The MP1584 has a dedicated enable control pin (EN). With high enough input voltage, the chip can be enabled and disabled by EN which has positive logic. Its falling threshold is a precision 1.2V, and its rising threshold is 1.5V (300mV higher). When floating, EN is pulled up to about 3.0V by an internal 1µA current source so it is enabled. To pull it down, 1µA current capability is needed. When EN is pulled down below 1.2V, the chip is put into the lowest shutdown current mode. When EN is higher than zero but lower than its rising threshold, the chip is still in shutdown mode but increases slightly. Under-Voltage Lockout (UVLO) Under-voltage lockout (UVLO) is implemented to protect the chip from operating at insufficient supply voltage. The UVLO rising threshold is about 3.0V while its falling threshold is a consistent 2.6V. the shutdown current the chip starts, Internal Soft-Start The soft-start is implemented to prevent the from overshooting converter output voltage during startup. When the internal circuitry generates a soft-start voltage (SS) ramping up from 0V to 2.6V. When it is lower than the internal reference (REF), SS overrides REF so the error amplifier uses SS as the reference. When SS is higher than REF, REF regains control. Thermal Shutdown Thermal shutdown is implemented to prevent the chip from operating at exceedingly high temperatures. When the silicon die temperature is higher than its upper threshold, it shuts down the whole chip. When the temperature is lower than its lower threshold, the chip is enabled again. Floating Driver and Bootstrap Charging The floating power MOSFET driver is powered by an external bootstrap capacitor. This floating driver has its own UVLO protection. This UVLO’s rising threshold is 2.2V with a threshold of 150mV. The bootstrap capacitor is charged and regulated to about 5V by the dedicated internal bootstrap regulator. When the voltage between the BST and SW nodes is lower than its regulation, a PMOS pass transistor connected from VIN to BST is turned on. The charging current path is from VIN, BST and then to SW. External circuit should provide enough voltage headroom to facilitate the charging. As long as VIN is sufficiently higher than SW, the bootstrap capacitor can be charged. When the power MOSFET is ON, VIN is about equal to SW so the bootstrap capacitor cannot be charged. When the external diode is on, the difference between VIN and SW is largest, thus making it the best period to charge. When there is no current in the inductor, SW equals the output voltage VOUT so the difference between VIN and VOUT can be used to charge the bootstrap capacitor. MP1584 Rev. 1.0 8/8/2011 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. www.MonolithicPower.com © 2011 MPS. All Rights Reserved. 8

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