MP1522ET

MP1522 25V Step-Up Converter in a SOT23-5 Package The Future of Analog IC Technology DESCRIPTION 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 packages. FEATURES • • • • • • • • • • • • 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 Packages Handheld Computers, PDAs Cell Phones Digital Still and Video Cameras Small LCD Displays APPLICATIONS EVALUATION BOARD REFERENCE Board Number EV0022 Dimensions 2.2”X x 1.5”Y x 0.5”Z “MPS” and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION VIN 3.3V 100 90 Efficiency vs Load Current with BIAS Tied to VOUT 10V 5.0V 3.3V OFF ON 4 EN SW 1 5 3 VOUT 20V C2 1nF EFFICIENCY (%) D1 RB751 80 70 60 MP1522 2 GND BIAS FB VOUT = 12V 50 1 10 100 1000 LOAD CURRENT (mA) MP1522 Rev. 2.0 9/1/2006 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. 1 MP1522 – 25V STEP-UP CONVERTER IN A SOT23-5 PACKAGE PACKAGE REFERENCE TOP VIEW SW GND FB 1 5 BIAS ABSOLUTE MAXIMUM RATINGS (1) 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 MARKING 4 EN 2 3 Recommended Operating Conditions (2) BIAS Supply Voltage ....................... 2.7V to 25V Output Voltage....................................VIN to 25V Operating Temperature .............–20°C to +85°C Thermal Resistance Part Number* MP1522ET * Package SOT23-5 Temperature –20°C to +85°C (3) SOT23-5 ................................ 220 .... 110.. °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. θJA θJC For Tape & Reel, add suffix –Z (eg. MP1522ET–Z) For RoHS Compliant Packaging, add suffix –LF (eg. MP1522ET–LF–Z) 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 FB Hysteresis (5) 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 Thermal Shutdown (5) Notes: 4) First 64 pulses after EN switches High 5) Guaranteed by design. Min 300 Typ 1 650 550 1.6 Max 3 750 700 Units µA µA ns µs 2.1 2.3 2.65 V 0.8 1.1 60 2.0 1 V mV µA V mV nA Ω mA µA °C 1.19 –150 1.23 10 –80 0.5 450 160 1.27 0.6 10 300 MP1522 Rev. 2.0 9/1/2006 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. 2 MP1522 – 25V STEP-UP CONVERTER IN A SOT23-5 PACKAGE PIN FUNCTIONS Pin # 1 2 3 4 Name SW GND FB EN 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 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. 5 BIAS OPERATION 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 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. L1 VIN C4 C1 BIAS SW D1 VOUT R3 5 1 R2 C2 C3 REGULATOR OFF ON EN GND INTERNAL POWER 4 CONTROL LOGIC CURRENT -+ 450mA 3 FB ERROR AMP -+ 1.23V GND R1 2 Figure 1—Functional Block Diagram MP1522 Rev. 2.0 9/1/2006 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2006 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 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) 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. 2.0 9/1/2006 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. © 2006 MPS. All Rights Reserved. 4 MP1522 – 25V STEP-UP CONVERTER IN A SOT23-5 PACKAGE 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 3.3V Table 1—Output Current vs. Input Voltage VIN (V) 3.3 3.3 3.3 3.3 5 5 5 10 10 10 VOUT (V) 5 12 18 25 12 18 25 12 18 25 IOUT (mA) 67 28 15 10 44 32 19 122 75 51 OFF ON 4 EN SW 1 5 3 D1 RB751 C2 1nF VOUT 20V MP1522 2 GND BIAS FB Figure 2—Typical Boost Application MP1522 Rev. 2.0 9/1/2006 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. 5 MP1522 – 25V STEP-UP CONVERTER IN A SOT23-5 PACKAGE PACKAGE INFORMATION SOT23-5 2.80 3.00 5 4 1.20 TYP 0.60 TYP 0.95 BSC 1.50 1.70 2.60 3.00 2.60 TYP 1 3 TOP VIEW RECOMMENDED LAND PATTERN 0.90 1.30 1.45 MAX SEATING PLANE 0.30 0.50 0.95 BSC 0.00 0.15 SEE DETAIL "A" 0.09 0.20 FRONT VIEW SIDE VIEW NOTE: GAUGE PLANE 0.25 BSC 1) ALL DIMENSIONS ARE IN MILLIMETERS. 2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH, PROTRUSION OR GATE BURR. 3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. 4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.10 MILLIMETERS MAX. 5) DRAWING CONFORMS TO JEDEC MO-178, VARIATION AA. 6) DRAWING IS NOT TO SCALE. 0o-8o 0.30 0.55 DETAIL A NOTICE: The information in this document is subject to change without notice. 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. 2.0 9/1/2006 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. 6