MP2115DQ

MP2115 MPS | Alldatasheet

Document overview

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Technical content

2A Synchronous Step-Down Converter with Programmable Input Current Limit MP2115 Rev. 1.0 www.MonolithicPower.com 1 2/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. The Future of Analog IC Technology

DESCRIPTION

The MP2115 is a high frequency, current mode, PWM step-down converter with integrated input current limit switch. The step-down converter integrates a main switch and a synchronous rectifier for high efficiency without an external Schottky diode. The input average current limit can be externally programmed. It is ideal for powering portable equipment that is powered by an USB port. The MP2115 can supply 2A of load current from a 2.8V to 6V input voltage. The output voltage can be regulated as low as 0.6V. The MP2115 is available in a space-saving 10-pin QFN package.

FEATURES

• High Efficiency: Up to 92%
• Programmable Switching Frequency from 0.7MHz-2MHz
• Programmable Input Current Limit
• 2A Available Load Current
• 2.8V to 6V Input Voltage Range
• Output Voltage as Low as 0.6V
• Current Mode Control
• Power Good Indicator
• Short Circuit Protection
• Thermal Fault Protection
• <0.1µA Shutdown Current
• Space Saving 3mm x 3mm QFN10 Package

APPLICATIONS

• USB Powered Devices
• Cellular and Smart Phones
• Microprocessors and DSP Core Supplies
• PDAs
• MP3 Players
• Digital Still and Video Cameras
• Portable Instruments For MPS green status, please visit MPS website under Quality Assurance. “MPS” and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION VIN 100k 100k 6TPE470MI x 3 USB Input VIN VSYS AGND FREG ILIM PGND FB SW EN PG MP2115DQ 86.6k 220pF 3.8V/2A 24.9k 51k 9.53k VSYS PG EN VOUT EFFICIENCY (%) Efficiency VOUT=3.8V, Freq=1.5MHz 100 LOAD CURRENT ( A ) VIN=5.0V VIN=5.5V

MP2115 – 2A, 6V SYNCHRONOUS STEP-DOWN CONVERTER MP2115 Rev. 1.0 www.MonolithicPower.com 2 2/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved.

ORDERING INFORMATION

Part Number* Package Top Marking Free Air Temperature (TA) MP2115DQ QFN10 (3mm x 3mm) 2X -40°C to +85°C * For Tape & Reel, add suffix –Z (e.g. MP2115DQ–Z). For RoHS compliant packaging, add suffix –LF (e.g. MP2115DQ–LF–Z) PACKAGE REFERENCE TOP VIEW EXPOSED PAD ON BACKSIDE CONNECT TO GND VIN ILIM FB GND FREQ PGND SW VSYS EN PG ABSOLUTE MAXIMUM RATINGS (1) VFB, VEN, PG, VSYS, ILIM to GND Continuous Power Dissipation (TA = +25°C) (2) Recommended Operating Conditions (3) Thermal Resistance (4) θJA θJC Notes: 1) Exceeding these ratings may damage the device. 2) The maximum allowable power dissipation is a function of the maximum junction temperature T J (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 P D (MAX) = (T J (MAX)-TA)/θJA. Exceeding the maximum allowable powe r 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.

MP2115 – 2A, 6V SYNCHRONOUS STEP-DOWN CONVERTER MP2115 Rev. 1.0 www.MonolithicPower.com 3 2/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. ELECTRICAL CHARACTERISTICS (5) VIN = VEN = 5.0V, TA = +25°C, unless otherwise noted. Parameter Symbol Condition Min Typ Max Units Supply Current V EN = VIN, VFB = 0.65V 800 1000 µA Shutdown Current V EN = 0V, VIN = 6V 0.10 1 µA IN Undervoltage Lockout Threshold Rising Edge 2.2 2.35 2.45 V IN Undervoltage Lockout Hysteresis 60 mV FB Input Bias Current V FB = 0.65V -50 0.5 +50 nA PFET On Resistance I SW = 100mA 0.1 Ω NFET On Resistance I SW = -100mA 0.1 Ω Load Switch PFET On Resistance 0.22 Ω Load Switch Current Set R ILIM=25kΩ 500 mA SW Leakage Current VEN = 0V, VIN = 6V, VSW = 0V or 6V -1 +1 µA PFET Current Limit （6） 3.5 A Oscillator Frequency f OSC R FREQ = 100kΩ 1.05 1.3 1.55 MHz Thermal Shutdown Trip Threshold 145 °C EN Input Low Voltage 0.3 1.32 1.45 V En Input High Voltage 1.65 1.75 2 V EN Input Current V IN = 0V to 6V -1 1 µA Power Good Ramp Up Threshold C5=220pF 80 % Power Good Ramp Down Threshold 70 % Soft Start Time 100 µs Power Good Sink Current Capability V PG Sink 4mA 0.5 V Power Good Leakage Current I PG LEAK V PG = 3.3V -50 50 nA Note: 5) 100% production test at +25°C. Spec ifications over the temperature range are guaranteed by design and characterization. 6）Guaranteed by design

MP2115 – 2A, 6V SYNCHRONOUS STEP-DOWN CONVERTER MP2115 Rev. 1.0 www.MonolithicPower.com 4 2/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. PIN FUNCTIONS Pin # Name Description 1 VIN Supply Input for the power stage. 2 ILIM Input Current Limit setting pin. A resistor from this pin to ground sets the input current limit. 3 FB Feedback Input. Connect FB to the center point of the external resistor divider. The feedback threshold voltage is 0.6V. 4 AGND Analog Ground. 5 FREQ Switching Frequency Program Input. Connect a resistor from this pin to ground to set the switching frequency. PGND Exposed Pad The exposed pad and PGND pin must be connected to the same ground plane. 7 SW Power Switch Output. Inductor connection to drains of the internal PFET and NFET switches. 8 VSYS Load switch output and switching regulator input. Us ually this pin connects to a large tantalum capacitor as energy reservoir. 9 EN On/Off Control Input. 10 PG Power good signal. When FB is less than 80% of 0.6V, PG is low. It is an open-drain output. Use a high value pull-up resistor externally to pull it up to system power supply.

MP2115 – 2A, 6V SYNCHRONOUS STEP-DOWN CONVERTER MP2115 Rev. 1.0 www.MonolithicPower.com 5 2/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. TYPICAL PERFORMANCE CHARACTERISTICS C1=10µF, C2=470µFx3, C4=220µF, C5=220pF, L= 4.7µH, TA = +25°C, unless otherwise noted. SWITCHING FREQUENCY (MHz) INPUT CURRENT (A) OUTPUT VOLTAGE (V) VINVOLTAGE(Y) Load Regulation Loop Gain with Phase Margin VIN = 5V, VOUT = 3.8V, IOUT = 0.5A FSW vs. Resistor V FB vs. Temperature VIN = 5V ILIMIT Resistor vs. Input Current Transient Response VIN = 5V, VOUT = 3.8V, IOUT = 0.7A/4.66ms FSW vs. Temperature VIN = 5V FREQUENCY (kHz) EFFICIENCY (%) LOAD CURRENT (A) LOAD CURRENT (A) Efficiency vs. Load Current VOUT = 3.8V, Freq=1.5MHz 3.860 3.862 3.864 3.866 3.868 3.870 -40 -30 -20 -10 0.1 1 10 100 1000 -180 -144 -108 -72 -36 108 144 180 0.4 0.8 1.2 1.6 2.0 50 100 150 200 250 300 350 400 VOUT 0.1V/div. IOUT 1A/div. VOUT 0.1V/div. IOUT 0.5A/div. 0.50 0.53 0.56 0.59 0.62 0.65 -40 -20 0 20 40 60 80 1 00 1.30 1.31 1.32 1.33 1.34 1.35 -40 -20 0 20 40 60 80 100 SWITCHING FREQUENCY (MHz) 100 VIN=5.0V VIN=5.5V

MP2115 – 2A, 6V SYNCHRONOUS STEP-DOWN CONVERTER MP2115 Rev. 1.0 www.MonolithicPower.com 6 2/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. TYPICAL PERFORMANCE CHARACTERISTICS (continued) C1=10µF, C2=470µFx3, C4=220µF, C5=220pF, L= 4.7µH, TA = +25°C, unless otherwise noted. VSYS 5V/div. VSW 5V/div. VOUT 2V/div. IL 0.5A/div. VSYS 5V/div. VPG 5V/div. VOUT 2V/div. IOUT 0.5A/div. VSYS 5V/div. VPG 5V/div. VOUT 2V/div. IOUT 0.5A/div. Steady State VIN = 5V, VEN put to VIN, VOUT = 3.8V, IOUT = 0.5A, Freq = 2MHz Power Ramp Up VIN = 5V, VEN put to VIN, VOUT = 3.8V, IOUT = 0.5A Power Ramp Down VIN = 5V, VEN put to VIN, VOUT = 3.8V, IOUT = 0.5A Steady State VIN = 5V, VEN put to VIN, VOUT = 3.8V, IOUT = 0.5A, Freq = 0.7MHz Enable Up VIN = 5V, VEN = 0-2V, VOUT = 3.8V, IOUT = 0.5A, Resistor Load Enable Down VIN = 5V, VEN = 2-0V, VOUT = 3.8V, IOUT = 0.5A, Resistor Load VOUT 2V/div. IL 5A/div. VOUT 2V/div. IL 2A/div. Short Circuit VIN = 5V, VEN put to VIN, VOUT = 3.8V Short Circuit Recovery VIN = 5V, VEN put to VIN, VOUT = 3.8V VSYS 5V/div. VSW 5V/div. VOUT 2V/div. IL 0.5A/div. VEN 2V/div. VSW 5V/div. VOUT 2V/div. IOUT 0.5A/div. VEN 2V/div. VSW 5V/div. VOUT 2V/div. IOUT 0.5A/div. IIN 0.1A/div. 0.5A

MP2115 – 2A, 6V SYNCHRONOUS STEP-DOWN CONVERTER MP2115 Rev. 1.0 www.MonolithicPower.com 7 2/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. FUNCTIONAL BLOCK DIAGRAM GND GND Input Current Limit ControlEN PG PGND FB ICS PWM ILIM OSCILLATOR Bias & Voltage Refernce PWM Control Logic 3.5A SW VIN VSYS ILIM ICS SLOP COMP EAO CC 17pF EAMP PWM COMP RZ 1M LIM FREQ AGND - + BG X10 FB 0. 6V DL DH OSC Figure 1—Functional Block Diagram

MP2115 – 2A, 6V SYNCHRONOUS STEP-DOWN CONVERTER MP2115 Rev. 1.0 www.MonolithicPower.com 8 2/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. OPERATION The MP2115 is a constant frequency current mode PWM step-down converter. The MP2115 is optimized for low voltage, USB port and Li- Ion battery powered applications where high efficiency and small size are critical. The MP2115 uses an external resistor divider to set the output voltage from 0.6V to 6V. The device integrates both a main switch and a synchronous rectifier, which provides high efficiency and eliminates an external Schottky diode. The MP2115 can achieve 100% duty cycle. The duty cycle D of a step-down converter is defined as: %100V V%100fTD IN OUT OSCON ×≈××= Where TON is the main switch on time, and f OSC is the oscillator frequency. Current Mode PWM Control Slope compensated current mode PWM control provides stable switching and cycle-by-cycle current limit for superior load and line response. This protects the internal main switch and synchronous rectifier. The MP2115 switch is programmable from 0.7MHz to 2MHz. During each cycle the PWM comparator modulates the power transferred to the load by changing the inductor peak current based on the feedback error voltage. During normal operation, the main switch is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, then switched off when the peak inductor current rises above the error voltage. When the main switch is off, the synchronous rectifier will turn on immediately and stay on until the next cycle starts. Dropout Operation The MP2115 allows the main switch to remain on for more than one switching cycle and increases the duty cycle when the input voltage drops close to the output voltage. When the duty cycle reaches 100%, the main switch continuously delivers current to the output up to the PFET current limit. The output voltage is the input voltage minus the voltage drop across the main switch and the inductor. Short Circuit Protection The MP2115 has short circuit protection. When the output is shorted to ground, the oscillator frequency is reduced to prevent the inductor current from increasing beyond the PFET current limit. The PFET current limit is also reduced to lower the short circuit current. The frequency and current limit will return to the normal values once the short circuit condition is removed and the feedback voltage reaches 0.6V. Maximum Load Current The MP2115 can operate down to a 2.8V input voltage; however the maximum load current decreases at lower input due to a large IR drop on the main switch and synchronous rectifier. The slope compensation signal reduces the peak inductor current as a function of the duty cycle to prevent sub-harmonic oscillations at duty cycles greater than 50%. Conversely the current limit increases as the duty cycle decreases. Programmable Input Current Limit The MP2115 has an input current limit protection function. It will insure that the input current doesn't exceed the maximum, when the input is supplied by the USB. Once the input current triggers the set current limit level, the output voltage will shut down and latch off until the input is reset. The input current limit resistor R5 value can be found from Table 1. Table 1—Resistor Selection vs. Input Current Setting VIN (V) VOUT (V) IOUT (A) R5 (kΩ) 5 3.8 0.2 47.2 0.3 33.3 0.4 25.75 0.45 23.29 0.5 24.9

MP2115 – 2A, 6V SYNCHRONOUS STEP-DOWN CONVERTER MP2115 Rev. 1.0 www.MonolithicPower.com 9 2/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved.

APPLICATION INFORMATION

The external resistor divider sets the output voltage (see Typical Application Circuit on page 1). The feedback resistor (R1) also sets the feedback loop bandwidth with the internal compensation capacitor (see Figure 1-Function Block Diagram). Choose R1 around 500k Ω for optimal transient response. R2 is then given by: 1V6.0 V 1R2R OUT − Table 2—Resistor Selection vs. Output Voltage Setting VOUT R1 R2 Inductor Selection A 1µH to 10µH inductor with DC current rating at least 25% higher than the maximum load current is recommended for most applications. For best efficiency, the inductor DC resistance shall be <200mΩ. See Table 3 for recommended inductors and manufacturers. For most designs, the inductance value can be derived from the following equation: OSCLIN OUTINOUT fIV VVV1L ×∆× −×= Where ∆IL is the Inductor Ripple Current. Choose inductor ripple current approximately 30% of the maximum load current, 2.5A. The maximum inductor peak current is: III L LOAD)MAX(L ∆+= Under light load conditions below 100mA, larger inductance is recommended for improved efficiency. Table 4 lists inductors recommended for this purpose. Table 3—Suggested Surface Mount Inductors Manufacturer Part Number Inductance ( µH) Max DCR ( Ω) Saturation Current (A) Dimensions LxWxH (mm3) Table 4—Inductors for Improved Efficiency at 25mA, 50mA, under 100mA Load. Manufacturer Part Number Inductance ( µH) Max DCR ( Ω) Saturation Current (A) IRMS (A) Coilcraft DO1605T-103MX 10 0.3 1.0 0.9 Murata LQH4C100K04 10 0.2 1.2 0.8 Sumida CR32-100 10 0.2 1.0 0.7 Sumida CR54-100 10 0.1 1.2 1.4

MP2115 – 2A, 6V SYNCHRONOUS STEP-DOWN CONVERTER MP2115 Rev. 1.0 www.MonolithicPower.com 10 2/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. Input Capacitor Selection The input capacitor (C1) reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency must be less than input source impedance to prevent high frequency switching current passing to the input. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. For most applications, a 10µF capacitor is sufficient. VSYS Capacitor Selection The VSYS capacitor C2 is used to supply the USB port and with the peak output current, such as during the TDM frame. That output peak current is about 2A. Use three 470 µF capacitors to avoid large voltage drops. Output Capacitor Selection The output capacitor (C4) keeps output voltage ripple small and ensures regulation loop stable. The output capacitor impedance should remain low at the switching frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended. The output ripple ∆ VOUT is approximately: ( ) −×≤∆ 2Cf8 1ESRLfV VVVV OSCOSCIN OUTINOUT OUT

MP2115 – 2A, 6V SYNCHRONOUS STEP-DOWN CONVERTER NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications. Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. MP2115 Rev. 1.0 www.MonolithicPower.com 11 2/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved.

PACKAGE INFORMATION

QFN10 (3mm x 3mm)