MP1517DR

MP1517 MPS | Alldatasheet

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Technical content

3A, 25V, 1.1MHz Step-Up Converter MP1517 Rev. 1.4 www.MonolithicPower.com 1 4/28/2006 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. The Future of Analog IC Technology

DESCRIPTION

The MP1517 is a 3A, fixed frequency step-up converter ideal for medium-to-high current step-up, flyback and SEPIC applications. The high 1.1MHz switching frequency allows for smaller external components producing a compact solution for size constrained cameras, PDAs and cell phones. The low 0.7V feedback voltage offers higher efficiency in white LED driver applications including cell phone camera flash. The MP1517 regulates the output voltage up to 25V with efficiencies as high as 95%. Soft-start, cycle-by-cycle current limiting, and input under voltage lockout prevent overstressing or damage to sensitive external circuitry at startup and output short-circuit conditions. Current-mode regulation and external compensation components allow the MP1517 control loop to be optimized over a wide variety of input voltage, output voltage, and load current conditions. The MP1517 is available in the thermally enhanced QFN16 (4mm x 4mm) package. EVALUATION BOARD REFERENCE Board Number Dimensions EV0043 2.5”X x 2.0”Y x 0.4”Z

FEATURES

• 4A Peak Current Limit
• Low 700mV Feedback Threshold
• Internal 150m Ω Power Switch
• Input Range of 2.6V to 25V
• Up to 95% Efficiency
• Zero Current Shutdown Mode
• Under Voltage Lockout Protection
• Open Load Protection
• Soft-Start Operation
• Thermal Shutdown
• Tiny 4mm x 4mm 16-Pin QFN Package

APPLICATIONS

• Boost and SEPIC Regulators
• Handheld Computers
• Cell Phone Camera Flash, PDAs
• Digital Still and Video Cameras “MPS” and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION MP1517 IN COMP FB SW 9, 10 SGND PGND 5, 13 11, 12 EN SS BP OLS 10nF 10nF 10nF OPTIONAL OFF ON VIN MBR320 VOUT 12V MP1517_TAC_S01 100 EFFICIENCY (%) LOAD CURRENT (mA) MP1517-EC01 Efficiency vs Load Current 1 10 100 1000 VIN = 5V VOUT = 12V VOUT = 18V

MP1517 – 3A, 25V, 1.1MHz STEP-UP CONVERTER MP1517 Rev. 1.4 www.MonolithicPower.com 2 4/28/2006 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. PACKAGE REFERENCE MP1517_PD01-QFN16 TOP VIEW EXPOSED PAD CONNECT TO PIN 13 PIN 1 IDENTIFICATION COMP NC BP EN PGND PGND SW SW 13141516 8765 INOLSNCSGND SGNDNCSSFB Part Number* Package Temperature MP1517DR QFN16 (4mm x 4mm) –40°C to +85°C * For Tape & Reel, add suffix –Z (eg. MP1517DR–Z) For Lead Free, add suffix –LF (eg. MP1517DR–LF–Z) ABSOLUTE MAXIMUM RATINGS (1) Voltage at All Other Recommended Operating Conditions (2) Thermal Resistance (3) θJA θJC Notes: 1) Exceeding these ratings may damage the device. 2) The device is not guaranteed to function outside of its operating conditions. 3) Measured on approximately 1” square of 1 oz. Copper.

ELECTRICAL CHARACTERISTICS

VIN = 5.0V, TA = +25°C, unless otherwise noted. Parameter Symbol Condition Min Typ Max Units IN Shutdown Supply Current VEN ≤ 0.3V 0.5 1.0 µA IN Operating Supply Current V EN > 2V, VFB = 0.8V 0.9 1.2 mA BP Voltage V IN = 2.6V to 25V 2.4 V IN Undervoltage Lockout Threshold V IN Rising 2.10 2.40 V IN Undervoltage Lockout Hysteresis 100 mV EN Input Low Voltage 0.4 V EN Input High Voltage 1.5 V EN Input Hysteresis 100 mV EN Input Bias Current 1 µA SW Switching Frequency f SW 0.9 1.1 1.3 MHz SW Maximum Duty Cycle V FB = 0.6V 85 93 % Error Amplifier Voltage Gain (4) A VEA 400 V/V Error Amplifier Transconductance G EA 350 µA/V COMP Maximum Output Current Sourcing and Sinking 30 µA FB Regulation Threshold 679 700 721 mV FB Input Bias Current V FB = 0.7V 1 µA SS Charging Current During Soft-Start 2 µA

MP1517 – 3A, 25V, 1.1MHz STEP-UP CONVERTER MP1517 Rev. 1.4 www.MonolithicPower.com 3 4/28/2006 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. ELECTRICAL CHARACTERISTICS (continued) VIN = 5.0V, TA = +25°C, unless otherwise noted. Parameter Symbol Condition Min Typ Max Units V IN = 5V 150 m Ω SW On Resistance (4) V IN = 3V 225 m Ω SW Current Limit (4) 3.0 4.0 A SW Leakage Current V SW = 25V 0.5 µA Thermal Shutdown (4) 160 °C Open Load Shutdown Threshold Measured at OLS Pin 27 V Note: 4) Guaranteed by design. TYPICAL PERFORMANCE CHARACTERISTICS 91.8 91.7 91.6 91.5 91.4 91.3 91.2 91.1 DUTY CYCLE (%) TEMPERATURE (°C) MP1517-TPC03 Maximum Duty Cycle vs Temperature 1.15 1.10 1.05 1.00 FREQUENCY (MHz) -50 0 50 100 150 TEMPERATURE (°C) MP1517-TPC02 Frequency vs Temperature 715 710 705 700 695 690 685 FEEDBACK VOLTAGE (mV) -50 0 50 100 150 TEMPERATURE (°C) MP1517-TPC01 Feedback Voltage vs Temperature -50 0 50 100 150 100 EFFICIENCY (%) LOAD CURRENT (mA) MP1517-EC01 Efficiency vs Load Current 1 10 100 1000 10000 VIN = 12V VOUT = 18V VOUT = 22V

MP1517 – 3A, 25V, 1.1MHz STEP-UP CONVERTER MP1517 Rev. 1.4 www.MonolithicPower.com 4 4/28/2006 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. TYPICAL PERFORMANCE CHARACTERISTICS (continued) 4.8 4.6 4.4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 CURRENT LIMIT (A) TEMPERATURE (°C) MP1517-TPC06 Current Limit vs Temperature 2.43 2.42 2.41 2.40 2.39 2.38 2.37 2.36 BP VOLTAGE (V) TEMPERATURE (°C) MP1517-TPC05 BP Voltage vs Temperature 940 920 900 880 860 840 820 -50 0 50 100 150 TEMPERATURE (°C) MP1517-TPC04 Operating Supply Current vs Temperature -50 0 50 100 150 -50 0 50 100 150 PIN FUNCTIONS Pin # Name Description 1 COMP Compensation: Error Amplifier Output. Connect to a series RC network to compensate the regulator control loop. 2, 6, 14 NC No Connect 3 BP Output of the Internal 2.4V Low Dropout Regulator. Connect a 10nF bypass capacitor between BP and SGND. Do not apply an external load to BP. 4 EN Regulator On/Off Control Input. A logic high input (VEN > 1.5V) turns on the regulator, a logic low puts it into low current shutdown mode. The EN pin cannot be left floating. 5, 13 SGND Signal Ground 7 OLS Open Load Shutdown Pin. OLS senses r egulator output voltage to protect IC during open load operation. When this pin’s voltage exceeds 27V, the output switch is shut off. The device then restarts in soft-start mode until it is disabled. 8 IN Input Supply Pin. This pin can be connected to the regulator’s input supply or to the output for boot-strapped operation. 9, 10 SW Output Switch Node. SW is the drain of the internal N-Channel MOSFET. Connect the inductor and rectifier to SW to complete the step-up converter. 11, 12 PGND Power Ground 15 SS Soft-Start Input. Connect a 10nF to 22nF capacitor from SS to SGND to set the soft-start time. SS sources 2µA to an external soft-start capacitor during startup. As the voltage at SS increases to 0.55V, the voltage at COMP is clamped to 0.7V above the voltage at SS limiting the startup current. The external capacitor at SS is discharged to ground when under voltage lockout, thermal shutdown occurs or open load shutdown occurs. 16 FB Regulation Feedback Input. The regulation threshold is 0.7V.

MP1517 – 3A, 25V, 1.1MHz STEP-UP CONVERTER MP1517 Rev. 1.4 www.MonolithicPower.com 6 4/28/2006 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. Internal Low-Dropout Regulator The internal power to the MP1517 is supplied from the IN pin through an internal 2.4V low- dropout linear regulator, whose output is BP. Bypass BP to SGND with a 10nF or greater capacitor to insure the MP1517 operates properly. The internal regulator can not supply any more current than is required to operate the MP1517, therefore do not apply any external load to BP. Soft-Start The MP1517 includes a soft-start timer that limits the voltage at COMP during startup to prevent excessive current at the input. This prevents premature termination of the source voltage at startup due to input current overshoot. When power is applied to the MP1517, and enable is asserted, a 2µA internal current source charges the external capacitor at SS. As the capacitor charges, the voltage at SS rises. The MP1517 internally clamps the voltage at COMP to 700mV above the voltage at SS. This limits the inductor current at startup, forcing the input current to rise slowly to the current required to regulate the output voltage. Open Load Shutdown The MP1517 includes an open load detect that will stop the output from switching. In a fault condition where the connection to the LED’s is open, V OUT will rise up. Once V OUT exceeds 27V, the MP1517 will stop switching and the output will stop rising. When the output falls below 27V the MP1517 will restart in soft-start mode and switches until the OLS threshold is exceeded again. This will continue until the part is disabled. To disable the open load shutdown feature, connect the OLS pin to GND.

APPLICATION INFORMATION

Setting the Output Voltage Set the output voltage by selecting the resistive voltage divider ratio. Use 10k Ω to 50k Ω for the low-side resistor R2 of the voltage divider. Determine the high-side resistor R1 by the equation: FB FBOUT V V - V2R1R ×= where VOUT is the output voltage. For R2 = 10kΩ and VFB = 0.7V, then R1 (kΩ) = 14.29kΩ (VOUT – 0.7V). Selecting the Inductor The inductor is required to force the higher output voltage while being driven by the input voltage. A larger value inductor results in less ripple current, resulting in lower peak inductor current and reducing stress on the internal N-Channel. MOSFET switch. However, the larger value inductor has a larger physical size, higher series resistance, and/or lower saturation current. Choose an inductor that does not saturate under the worst-case load transient and startup conditions. A good rule for determining the inductance is to allow the peak-to-peak ripple current to be approximately 30% to 50% of the maximum input current. Make sure that the peak inductor current is below 3A to prevent loss of regulation due to the current limit. Calculate the required inductance value by the equation: IfV ) V- (VVL SWOUT INOUTIN ∆×× IN )MAX(LOADOUT )MAX(IN V IV I ( ) )MAX(INI%50%30I ×−=∆ Where V IN is the input voltage, SWf is the switching frequency, I LOAD(MAX) is the maximum load current, ∆I is the peak-to-peak inductor ripple current and η is the efficiency. Selecting the Input Capacitor An input capacitor is required to supply the AC ripple current to the inductor, while limiting noise at the input source. A low ESR capacitor is required to keep the noise at the IC to a minimum. Ceramic capacitors are preferred, but tantalum or low-ESR electrolytic capacitors may also suffice.

MP1517 – 3A, 25V, 1.1MHz STEP-UP CONVERTER MP1517 Rev. 1.4 www.MonolithicPower.com 7 4/28/2006 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. Use an input capacitor value greater than 10µF. The capacitor can be electrolytic, tantalum or ceramic. However since it absorbs the input switching current it requires an adequate ripple current rating. Use a capacitor with RMS current rating greater than the inductor ripple current. To insure stable operation place the input capacitor as close to the IC as possible. Alternately a smaller high quality ceramic 0.1µF capacitor may be placed closer to the IC with the larger capacitor placed further away. If using this technique, it is recommended that the larger capacitor be a tantalum or electrolytic type. All ceramic capacitors should be placed close to the MP1517. Selecting the Output Capacitor The output capacitor is required to maintain the DC output voltage. Low ESR capacitors are preferred to keep the output voltage ripple to a minimum. The characteristic of the output capacitor also affects the stability of the regulation control system. Ceramic, tantalum, or low ESR electrolytic capacitors are recommended. In the case of ceramic capacitors, the impedance of the capacitor at the switching frequency is dominated by the capacitance, and so the output voltage ripple is mostly independent of the ESR. The output voltage ripple is calculated as: ( ) SWUTO INUTOLOAD RIPPLE f2CV VVIV ×× −×= Where VRIPPLE is the output ripple voltage, VIN and VOUT are the DC input and output voltages respectively, ILOAD is the load current, f SW is the switching frequency, and C2 is the capacitance of the output capacitor. In the case of tantalum or low-ESR electrolytic capacitors, the ESR dominates the impedance at the switching frequency, and so the output ripple is calculated as: ⎡ ×+×× −×= IN OUTESR SWOUT INOUT LOADRIPPLE V VR 2CfV )VV(IV Where RESR is the equivalent series resistance of the output capacitors. Choose an output capacitor to satisfy the output ripple and load transient requirements of the design. Place the output capacitor close to SW to minimize the AC loop and switching noise. Selecting the Diode The output rectifier diode supplies current to the inductor when the internal MOSFET is off. To reduce losses due to diode forward voltage and recovery time, use a Schottky diode. Choose a diode whose maximum reverse voltage rating is greater than the maximum output voltage. The rated average forward current needs to be equal to or greater than the load current. Selecting the Soft-Start Capacitor The soft-start period is determined by the equation: C4 0.275 tSS ×= Where C SS (in nF) is the soft-start capacitor from SS to SGND, and t SS (in ms) is the soft-start period. Determine the capacitor required for a given soft-start period by the equation: SSt 3.64 C4 ×= It is recommended that values between 10nF and 22nF for CSS be used to set the soft-start period. Compensation The output of the transconductance error amplifier (COMP) is used to compensate the regulation control system. The system uses two poles and one zero to stabilize the control loop. The poles are f P1 set by the output capacitor and load resistance and f P2 set by the compensation capacitor C3. The zero f Z1 is set by the compensation capacitor C3 and the compensation resistor R3. These are determined by the equations: fP1 = LOADR C2 ××π fP2 = VEA EA A C3 2 G ××π× fZ1 = R3 C3 2 ××π× Where R LOAD is the load resistance, G EA is the error amplifier transconductance, and A VEA is the error amplifier voltage gain.

MP1517 – 3A, 25V, 1.1MHz STEP-UP CONVERTER MP1517 Rev. 1.4 www.MonolithicPower.com 8 4/28/2006 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. The DC loop gain is: AVDC = 2 OUT FBLOADIN VEA V V R V A7 ×××× Where VFB is the feedback regulation threshold. There is also a right-half-plane zero (f RHPZ) that exists in the continuous conduction mode (inductor current does not drop to zero on each cycle) step-up converters. The frequency of the right-half plane zero is: f RHPZ = 2 OUT LOAD IN VL2 R V ××π× To stabilize the regulation control loop, the crossover frequency (The frequency where the loop gain drops to 0dB or a gain of 1) should be less than half of f RHPZ and should be at most 75KHz. f RHPZ is at its lowest frequency at maximum output load current. In some cases, an output capacitor with a high capacitance and high equivalent series resistance (ESR) is used, then a second compensation capacitor (from COMP to SGND) is required to compensate for the zero introduced by the output capacitor ESR. The extra capacitor is required if the ESR zero is less than 4x the crossover frequency. The ESR zero frequency is: f ZESR = ESRR C2 2 ××π× If this is the case, calculate the second compensation capacitor by the equation: C6 = 3R RC2 ESR× For most applications C6 is not required. Typical values for the compensation components are: C3 = 10nF R3 = 2.2kΩ SEPIC CONVERTER COMPONENT SELECTION Selecting the Input Capacitor An input capacitor is required to supply the AC ripple current to the inductor, while limiting noise at the input source. The input capacitor selection is the same as that in the General Purpose Component Selection section above. Selecting the Inductors The SEPIC converter inductors (refer to Figure 4) are required to store energy, and generate an output voltage that is less than or greater than the input voltage. If a coupled inductor is used in a SEPIC converter, then the mutual inductance of each winding forces each inductor to become twice the original inductance. Therefore smaller inductance can be used with a coupled inductor. But the core saturation of the coupled inductors is related to the sum of both inductor currents. There are two current paths to the internal N-Channel MOSFET switch in a SEPIC converter. One is from L1 and the other is from L2. Each inductor’s ripple current can be defined as: I f D V1L SW IN I f D) 1( V2L SW UTO −×= INDOUT DOUT VVV V VD ++ Where VD is the voltage drop on diode D1, and ∆I is the peak to peak inductor ripple current. Set ∆I to approximately 20% of the maximum switch current. Each inductor’s peak current is: IN DOUT LOAD)PEAK(1L V VVI2 II +×+∆= IN DIN LOAD)PEAK(2L V VVI2 II +×+∆= The total of these two currents is the total switch current, and should be less than the minimum device current limit of 3A.

MP1517 – 3A, 25V, 1.1MHz STEP-UP CONVERTER MP1517 Rev. 1.4 www.MonolithicPower.com 12 4/28/2006 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. MP1517 IN COMP FB SW SGND PGND EN SS BP OLS 10nF 10nF 47nF OFF ON VIN MBRS130 VP1-0059 VERSA-PAC STANDARD MULTI-WINDING XFMR VOUT1 12V/0.2A VOUT2 -12V/0.2A MP1517_F06 MBRS130 9, 10 5, 13 11, 12 Figure 6—±12V SEPIC Application Circuit

MP1517 – 3A, 25V, 1.1MHz STEP-UP CONVERTER NOTICE: The information in this document is subject to change wi thout notice. Please contact MPS for current specifications. Users should warrant and guarantee that third party Intellectual Property rights ar e not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. MP1517 Rev. 1.4 www.MonolithicPower.com 13 4/28/2006 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved.

PACKAGE INFORMATION

QFN16 (4mm x 4mm) SIDE VIEW TOP VIEW 1613 BOTTOM VIEW 3.90 4.10 2.15 2.45 3.90 4.10 2.15 2.45 0.65 BSC 0.25 0.35 0.80 1.00 0.00 0.05

0.20 REF

2.30 0.65 0.35 RECOMMENDED LAND PATTERN

3.80 NOTE:

1) ALL DIMENSIONS ARE IN MILLIMETERS. 2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH. 3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX. 4) JEDEC REFERENCE IS MO-220, VARIATION VGGC. 5) DRAWING IS NOT TO SCALE. PIN 1 ID SEE DETAIL A PIN 1 ID OPTION A 0.45x45º TYP. PIN 1 ID OPTION B R0.25 TYP. DETAIL A PIN 1 ID INDEX AREA 1.00 0.50 0.70