GPM9081 1.2 MHz Step-up DC/DC Converters General Description Features The GPM9081 step-up switching regulator generates an output voltage of up to 6V from an input voltage as low as 1.6V. Ideal for applications where space is limited, it switches at 1.2MHz, allowing the use of tiny, low cost and low profile external components. Its internal 2A, 100mΩ NMOS switch provides high efficiency even at heavy load, while the constant frequency, current mode architecture results in low, predictable output noise that is easy to filter. Internal frequency compensation is designed to accommodate ceramic output capacitors, further reducing noise. The device features very low shutdown current of 0.5uA. The GPM9081 is available in SOT-23-6 package. • • • • • Internal 2A MOSFET Switch 1.2MHZ Switching Frequency Integrated Soft-Start Low 1.6V Vin Operation Low Rds ( on ) Switch :100mΩ at 5V Output • • • • Delivers 5V at 800mA from a 3.3V input Delivers 3V at 800mA from a 2.5V input Cost effective for using smaller devices Low profile(1mm):SOT-23-6 package Application • • • White LED Driver Supply Local 3.3V or 5V supply Battery Back-up Figure 1 Typical Application Circuit ONE THREE SIX ZERO ZERO TWO FIVE NINE SEVEN DOUBLE NINE,MR.CHEN 1 GPM9081 1.2 MHz Step-up DC/DC Converters ______________________________________ ______________________________________________________________ Ordering Information Part Number Temp Range Switching Frequency Output Voltage (V) Output Current (A) Package Pins Top Mark GPM9081 -40°C to 85°C 1.2MHz Adjustable 2 SOT23-6 6 GPM9081 Pin Configuration SOT23-6 Figure 2 PIN Configuration Pin Description PIN NUMBER PIN NAME PIN DESCRIPTION 1 SW Switch Output. Connect this pin to the inductor. 2 GND Ground. 3 FB Feedback Input. The voltage at this pin is regulated to 0.6V. Connect to the resistor divider between output and ground to set output voltage 4 EN Enable Input. When higher than 1.5V, this pin turns the IC on. When lower than 0.3V, this pin turns the IC off. 5 Vin Power Supply 6 Vin Power Supply Absolute Maximum Ratings (Note: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions for long periods may affect device reliability.) PARAMETER Supply Voltage VIN VALUE UNIT -0.3 to 6.5 V ONE THREE SIX ZERO ZERO TWO FIVE NINE SEVEN DOUBLE NINE,MR.CHEN 2 GPM9081 1.2 MHz Step-up DC/DC Converters ______________________________________ ______________________________________________________________ FB, EN Voltage -0.3 to VIN+0.3 V SW Voltage Operating Ambient Temperature -0.3 to VIN+0.3 V -40 to 85 °C Maximum Junction Temperature Storage Temperature 125 °C -55 to 150 °C 300 °C Lead Temperature (Soldering, 10 sec) Electrical Characteristics (VIN = 3.6V, TA= 25°C unless otherwise specified) PARAMETER Input Voltage Range SYMBOL VIN Quiescent Current Shutdown Current Regulated Feedback Voltage TEST CONDITIONS Iq VFB Reference Voltage Line Regulation MIN 1.6 MAX UNIT 6.0 V VFB =0.7V EN=Vin, ILoad =0 65 120 VEN =0V, VIN =3.3V 0.5 1 Ta =25°C 0.588 0.6 0.612 0< Ta < 85°C 0.6865 0.6 0.6135 -40°C < Ta <85°C 0.585 0.6 0.615 0.05 0.5 VIN =1.6V to 5.5V Output Voltage Load Regulation 0.5 Current Limit IPEAK Oscillator Frequency FOSC VFB=0.6V or VOUT =100% Rds(ON) of N-channel FET ISW =-100mA Enable Threshold VIN = 1.6V to 5.5V Enable Leakage Current SW Leakage Current TYP 0.9 0.3 -0.1 VEN = 0V, VSW = 0V or 5V, VIN = 5V ONE THREE SIX ZERO ZERO TWO FIVE NINE SEVEN DOUBLE NINE,MR.CHEN uA V % % 2 2.4 A 1.2 1.5 MHz 100 200 mΩ 1 1.5 V 0.1 1 µA uA 3 GPM9081 1.2 MHz Step-up DC/DC Converters ______________________________________ ______________________________________________________________ Figure 3 Functional Block Diagram FUNCTIONAL DESCRIPTION NORMAL OPERATION The GPM9081 is a monolithic 1.2MHz boost converter housed in a 6-lead SOT-23 package. The device features fixed frequency, current mode PWM control for excellent line and load regulation. The low Rds ( on ) NMOS switch enables the device to maintain high efficiency over a wide range of load current. Operation of the feedback loop which sets the peak inductor current to keep the output in regulation can be best understood by referring to the Block Diagram in Figure 1. At the start of each clock cycle a latch in the PWM logic is set and the NMOS switch is turned on. The sum of a voltage proportional to the switch current and a slope compensating voltage ramp is fed to the positive input to the PWM ONE THREE SIX ZERO ZERO TWO FIVE NINE SEVEN DOUBLE NINE,MR.CHEN 4 GPM9081 1.2 MHz Step-up DC/DC Converters ______________________________________ ______________________________________________________________ comparator. When this voltage exceeds either a voltage proportional to the 2A current limit or the PWM control voltage, the latch in the PWM logic is reset and NMOS switch is turned off. The PWM control voltage at the output of the error amplifier is the amplified and compensated difference between the feed- back voltage on the FB pin and the internal reference voltage of 0.6V. If the control voltage increases, more current is delivered to the output. When the control voltage exceeds the ILIMIT reference voltage, the peak current is limited to a minimum of 2A. The current limit helps protect the GPM9081 internal switch and external components connected to it. If the control voltage decreases, less current is delivered to the output. During load transients control voltage may decrease to the point where no switching occurs until the feedback voltage drops below the reference. The GPM9081 has an integrated soft-start feature which slowly ramps up the feedback control node from 0V. The soft-start is initiated when EN is pulled high. APPLICATION INFORMATION INDUCTOR SELECTION The GPM9081 can utilize small surface mount inductors due to its 1.2MHz switching frequency. A 2.2μH or 4.7μH inductor will be the best choice for most GPM9081 applications. The inductor should have low DCR (DC resistance) to reduce the I2R power losses, and must be able to handle the peak inductor current without saturating. Several inductor manufacturers are listed in Table 1 Selected inductor by actual application: Part Induct DRC Manuf acture Number ance( max (Ohm r uH) s) Dimension s L*W*H(mm 3) Murata LQH5B PN 5*5*2 LQH32P N Sumid a CDRH3 D16 2.2 0.03 2.2 0.06 2.2 0.03 4.7 0.07 3.2*2.5*1.7 4*4*1.8 Table 1. Recommend Surface Mount Inductors Diode Selection A Schottky diode is recommended for use with the GPM9081.Use of a low forward voltage diode such as the ON Semiconductor MBRA210LT3 is recommended. A Schottky diode rated at 2A is recommended for use with the GPM9081. to the converter, low ESR ceramic capacitor is highly recommended. For most applications, a 10~22uF capacitor is used. The input capacitor should be placed as close as possible to VIN and GND. Recommended: Murata GRM32ER61A106KA01L Murata GRM32NR61A226KE19L OUTPUT CAPACITOR SELECTION A low ESR output capacitor is required in order to maintain low output voltage ripple. In the case of ceramic output capacitors, capacitor ESR is very small and does not contribute to the ripple, so a lower capacitance value is acceptable when ceramic capacitors are used. A 22uF ceramic output capacitor is suitable for most applications. Recommended: Murata GRM32NR61A226KE19L OUTPUT VOLTAGE PROGRAMMING In the adjustable version, the output voltage is set by a resistive divider according to the following equation: ⎛V ⎞ R2 = R1 × ⎜ OUT − 1⎟ ⎝ 0.6 ⎠ Typically choose R1=100K and determine R2 from the following equation: Connect a small capacitor across R1 feed forward capacitance at the FB pin for better performance. INPUT CAPACITOR SELECTION The input capacitor reduces input voltage ripple ONE THREE SIX ZERO ZERO TWO FIVE NINE SEVEN DOUBLE NINE,MR.CHEN 5 GPM9081 1.2 MHz Step-up DC/DC Converters ______________________________________ ______________________________________________________________ PCB Layout Guidelines The high speed operation of the GPM9081 demands careful attention to board layout. You will not get advertised performance with careless layout. Figure as below shows the recommended component placement. A large ground pin copper area will help to lower the chip temperature. ONE THREE SIX ZERO ZERO TWO FIVE NINE SEVEN DOUBLE NINE,MR.CHEN 6 GPM9081 1.2MHz Step-up DC/DC Converter Typical Performance Characteristics Efficiency vs. Output Current2 Efficiency vs. Output Current1 Startup through Enable Waveform Startup waveform (Vin=1.8V EN=0->1.8V Vout=3.3V) (Vin=EN=1.8V Vout=3.3V) IOUT(MAX) vs VIN(Vout=3.3V) Reference Voltage vs. Temperature Notes: The efficiency is tested under normal temperature , the actual current driver capability is 70% ~90% of the max current in sheet according surrounding status. ONE THREE SIX ZERO ZERO TWO FIVE NINE SEVEN DOUBLE NINE,MR.CHEN 7 GPM9081 1.2MHz Step-up DC/DC Converter Package Outline SOP8-PP Package Outline and Dimensions A A1 A2 B C D E E1 Dimension in Millimeters MIN MAX 1.35 1.75 0.100 0.250 1.350 1.550 0.330 0.510 0.190 0.250 4.700 5.100 3.800 4.000 5.800 6.300 Dimension in Inches MIN MAX 0.053 0.069 0.004 0.010 0.053 0.061 0.013 0.020 0.007 0.010 0.185 0.201 0.150 0.157 0.228 0.248 e L 1.27 TYP 0.400 1.270 0.050 TYP 0.016 0.050 SYMBOL θ 0o ONE THREE SIX ZERO ZERO TWO FIVE NINE SEVEN DOUBLE NINE,MR.CHEN 8o 0o 8o 8