MP1522 25V Step-Up Converter in a SOT23-5 Package The Future of Analog IC Technology DESCRIPTION FEATURES The MP1522 is a step up converter that generates up to a 25V output voltage from a 2.7V to 25V input. It uses a current limited Variable Frequency control algorithm to optimize efficiency and minimize external component size and cost. The internal 0.5Ω N-Channel MOSFET switch can withstand up to 28V allowing the MP1522 to produce high output voltage with high efficiency. • • • • • • • • The MP1522 includes input under voltage and over temperature protection. The MP1522 is available in tiny 5-pin SOT23 and 3x3 QFN6 packages. EVALUATION BOARD REFERENCE Board Number Dimensions EV0022 2.2”X x 1.5”Y x 0.5”Z Internal 0.5Ω Power Switch Output Voltage up to 25V Up to 90% Efficiency Low 1µA Shutdown Current Input Under Voltage Protection Thermal Shutdown Internal Current Limit Available in Tiny 5-Pin SOT23 and 6-Pin 3x3 QFN Packages APPLICATIONS • • • • Handheld Computers, PDAs Cell Phones Digital Still and Video Cameras Small LCD Displays “MPS” and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION VIN 3.3V 100 Efficiency vs Load Current with BIAS Tied to VOUT 10V 4 EN SW MP1522 2 GND BIAS FB 1 5 VOUT 20V C2 1nF 3 EFFICIENCY (%) OFF ON 90 D1 RB751 5.0V 3.3V 80 70 60 VOUT = 12V 50 1 MP1522_TAC_S01 10 100 1000 LOAD CURRENT (mA) MP1522_TAC_EC01 MP1522 Rev. 1.9 12/9/2005 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2005 MPS. All Rights Reserved. 1 MP1522 – 25V STEP-UP CONVERTER IN A SOT23-5 PACKAGE ABSOLUTE MAXIMUM RATINGS (1) PACKAGE REFERENCE TOP VIEW 1 GND 2 FB 3 5 BIAS MARKING SW Recommended Operating Conditions 4 EN MP1522_PD01-TSOT23-5 Part Number* * BIAS .............................................. –0.3V to 28V SW ................................................. –0.5V to 28V All Other Pins................................... –0.3V to 6V Junction Temperature...............................150°C Solder Temperature..................................260°C Storage Temperature ................–65°C to 150°C Package Temperature MP1522ET SOT23-5 –20°C to +85°C MP1522EQ 3x3 QFN6 –20°C to +85°C For Tape & Reel, add suffix –Z (eg. MP1522ET–Z) For Lead Free, add suffix –LF (eg. MP1522ET–LF–Z) (2) BIAS Supply Voltage ....................... 2.7V to 25V Output Voltage....................................VIN to 25V Operating Temperature .............–20°C to +85°C Thermal Resistance (3) θJA θJC SOT23-5 ................................ 220 .... 110.. °C/W 3x3 QFN6 ............................... 50 ...... 14... °C/W 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 VBIAS = VEN = 5.0V, TA = +25°C, unless otherwise noted. Parameter Symbol Condition Supply Current (Shutdown) IBIAS (OFF) VEN = 0V Supply Current (Quiescent) IBIAS(ON) VFB = 1.3V Min Off Time, Normal TOFF VFB = 1.23V Operation Min Off Time, Start-Up (4) TOFF VFB = 0V Undervoltage Lockout BIAS Under Voltage Lockout UVLO VBIAS Rising, 100mV Hysteresis (Typical) Enable EN Threshold VEN Rising EN Hysteresis EN Input Bias Current VEN = 0V, 5V Feedback Comparator FB Regulation Threshold VFB Falling (5) FB Hysteresis FB Input Bias Current VFB = 1.23V Output Switch SW On-Resistance (5) RON VBIAS = 5.0V SW Current Limit SW Leakage Current VSW=25V (5) Thermal Shutdown Min 300 Typ 1 650 550 Max 3 750 700 1.6 Units µA µA ns µs 2.1 2.3 2.65 V 0.8 1.1 60 2.0 V mV µA 1 1.19 1.27 –150 1.23 10 –80 V mV nA 0.5 450 0.6 300 Ω mA µA °C 10 160 Notes: 4) First 64 pulses after EN switches High 5) Guaranteed by design. MP1522 Rev. 1.9 12/9/2005 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2005 MPS. All Rights Reserved. 2 MP1522 – 25V STEP-UP CONVERTER IN A SOT23-5 PACKAGE PIN FUNCTIONS Pin # Name 1 SW 2 3 GND FB 4 EN 5 BIAS Description Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the power inductor and output rectifier to SW. SW can swing between GND and 25V. Ground. Feedback Input. Connect a resistive voltage divider from the output voltage to FB to set the output voltage. The feedback regulation threshold is 1.23V. Regulator On/Off Control Input. A high voltage at EN turns on the converter, and a low voltage turns it off. When not used, connect EN to the input source for automatic startup. If EN is driven over 6V, place a 100kΩ resistor in series with EN. Internal Power Input. BIAS powers the internal circuitry. Connect BIAS to the output for more enhancement on the internal MOSFET gate at low VIN. If the input source remains above 3.0V, BIAS can be connected to the input source to reduce power consumption. OPERATION start-up to yield a smooth glitch free turn-on. Start-up mode is activated at initial power-up or when exiting the 1µA shutdown state. The MP1522 features an internal regulator allowing it to be powered from the output for improved low-input voltage operation, or powered from the input source for reduced power consumption due to quiescent current. The MP1522 is a step-up converter that operates from an input voltage as low as 2.7V and generates an output voltage up to 25V. The 0.5Ω internal N-Channel MOSFET power switch is driven with a variable frequency, constantpeak-current architecture for improved regulation and low operating current. The 550ns minimum off-time is extended to 1.6µs during L1 VIN VOUT C4 C1 OFF ON D1 BIAS (5) R3 SW (1) R2 REGULATOR EN (4) C2 C3 GND INTERNAL POWER CONTROL LOGIC CURRENT -+ 450mA FB (3) ERROR AMP -- R1 + 1.23V GND (2) MP1522_BD01 Figure 1—Functional Block Diagram MP1522 Rev. 1.9 12/9/2005 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2005 MPS. All Rights Reserved. 3 MP1522 – 25V STEP-UP CONVERTER IN A SOT23-5 PACKAGE Variable Frequency Constant-Peak-Current Operation When the power MOSFET is turned on the inductor current increases until the 0.45A current limit is reached. The Power MOSFET is then turned off for a minimum of 550ns. At the end of this 550ns transition if the feedback pin is still lower than the 1.23V internal reference the power MOSFET will again be turned on, otherwise the MP1522 waits until the voltage drops below the threshold before turning on the MOSFET again. This process allows for optimal use of the inductor, while minimizing the output ripple and size of the output capacitor and maintaining low operating current. Setting the Output Voltage The output voltage is set by a resistive voltage divider connecting the output voltage to FB. The voltage divider reduces the output voltage down by the ratio: VOUT R1 + R2 = VFB R1 Solving for VOUT ⎛ R1 + R2 ⎞ VOUT = VFB ⎜ ⎟ ⎝ R1 ⎠ Where VOUT is the output voltage, and VFB is the 1.23V feedback threshold. Substituting the feedback threshold voltage: ⎛ R1 + R2 ⎞ VOUT = 1.23 V ⎜ ⎟ ⎝ R1 ⎠ R1 can range from 10kΩ to 200kΩ. R2 is determined the equation: ⎡⎛ V R2 = R1⎢⎜⎜ OUT ⎢⎣⎝ VFB ⎞ ⎤ ⎟⎟ − 1⎥ ⎠ ⎥⎦ For example for an output voltage of 20V and R1 = 130kΩ the formula yields: ⎡⎛ 20 ⎞ ⎤ R2 = 130kΩ ⎢⎜ ⎟ − 1⎥ ⎣⎝ 1.23 V ⎠ ⎦ R2 = 2MΩ the closest standard 1% resistor value. The feedback divider requires a feed-forward capacitor connected in parallel with R2. This capacitor is typically in the range of 1nF-10nF. MP1522 Rev. 1.9 12/9/2005 On/Off Control The EN input is used to turn the converter on and off. A high input at EN turns the converter on and a low level turns the converter off. When EN is not being used, connect to the input source for automatic startup. For inputs greater than 6V, pull EN to VIN through a 100kΩ resistor. Input Capacitor To reduce noise, use a low ESR/ESL type input capacitor. A 1µF surface mount ceramic capacitor close to the input supply side of the inductor minimizes EMI and ripple current at the input source. See the section on printed circuit board layout for reducing noise and emissions. A bypass capacitor is typically required to prevent noise at the MP1522. This capacitor should also be a low ESR/ESL type capacitor. Place a 0.1µF surface mount ceramic capacitor between BIAS and GND as close to the MP1522 as possible. Output Capacitor To minimize output voltage ripple and noise use a low ESR/ESL type output capacitor. Typically a 1µF surface mount ceramic capacitor is sufficient. When using aluminum electrolytics, tantalum or aluminum polymer capacitors the ESR/ESL dominate the output ripple. See the section on printed circuit board layout. Inductor The inductor stores energy during the power MOSFET switch on-time. This energy is transferred to the output during the switch offtime. Select an inductor whose peak-current rating is greater than the 450mA peak current limit of the MP1522. Lower value inductors yield higher switching frequencies and thus lower output ripple voltage. However, using too low a value inductor will cause an increase in peak current limit due to the delay of the current-limit comparator. Choose an inductor such that the peak current limit is reached in 550ns or longer. The minimum value inductor for this criterion is: L ≥ 1.31 × 10 −6 × VIN (µH) For maximum VIN = 3.3V, use an inductor value greater than 4.7µH, and for maximum VIN = 5V use an inductor value greater than 6.8µH. www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2005 MPS. All Rights Reserved. 4 MP1522 – 25V STEP-UP CONVERTER IN A SOT23-5 PACKAGE Table 1—Output Current vs. Input Voltage Diode The high switching frequencies of the MP1522 require the use of fast recovery or Schottky barrier diodes. In low voltage applications Schottky barrier diodes are recommended for maximum efficiency. The reverse breakdown voltage should be approximately 1.5X the output voltage. Printed Circuit Board Layout The printed circuit board layout is important in order to minimize noise and prevent erratic operation. Keep the ground leads short and robust with minimum lead lengths between the input and output capacitors and ground. Place the feedback resistive voltage divider as close to FB as possible to prevent switching noise injection into FB. The use of surface mount capacitors with their low ESL is required to minimize noise at the MP1522. Use separate power and quiet ground planes connected together at a single point whenever possible to minimize.ground.bounce. VIN (V) VOUT (V) IOUT (mA) 3.3 3.3 3.3 3.3 5 5 5 10 10 10 5 12 18 25 12 18 25 12 18 25 67 28 15 10 44 32 19 122 75 51 VIN 3.3V OFF ON 4 EN SW MP1522 2 GND BIAS FB 1 D1 RB751 5 VOUT 20V C2 1nF 3 MP1522_TAC_F02 Figure 2—Typical Boost Application MP1522 Rev. 1.9 12/9/2005 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2005 MPS. All Rights Reserved. 5 MP1522 – 25V STEP-UP CONVERTER IN A SOT23-5 PACKAGE PACKAGE INFORMATION SOT23-5 2.90±0.100 0.950 TYP. 5 0 10 TYP. (2 plcs) 0.950 TYP. C L 0°~3° 0.20 BSC. Gauge Plane 0.350(MIN) 0.500(MAX) (5 PLCS) 0.45 ±0.10 CL 0.127 TYP 0 10 TYP. (2 plcs) 0 10 TYP. (2 plcs) 0 10 TYP. (2 plcs) 0.05(MIN) 0.15(MAX) Dimensions are in millimeters NOTE: 1. Dimensions and tolerances are as per ANSI Y14.5M, 1982. 2. Package surface to be matte finish VDI 11~13. 3. Die is facing up for mold. Die is facing down for trim/form, ie. reverse trim/form. 4. The footlength measuring is based on the gauge plane method. 5. Dimensions are exclusive of mold flash and gate burr. MP1522 Rev. 1.9 12/9/2005 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2005 MPS. All Rights Reserved. 6 MP1522 – 25V STEP-UP CONVERTER IN A SOT23-5 PACKAGE 3x3 QFN6 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. MP1522 Rev. 1.9 12/9/2005 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2005 MPS. All Rights Reserved. 7