ACT6308

Rev PrB, 20-Feb-08 Preliminary Product Information―All Information Subject to Change ACT6308 Low Input High Efficiency Synchronous Step-Up DC/DC Converter FEATURES • • • • • • 1V Typical Startup Voltage Up to 89% Efficiency Fully Integrated Power Stage Fixed 3.3V/5V or Adjustable Output Voltage NanoStandbyTM Shutdown Mode Tiny SOT23-5 Package − RoHS Compliant Package GENERAL DESCRIPTION The ACT6308 is a high efficiency synchronous step-up DC/DC converter that consumes just 17µA of quiescent supply current using only three external components. This device achieves a typical startup voltage of just 1V, making it ideal for applications operating from 1 or 2 alkaline cells. This device incorporates an internal synchronous rectifier, and achieves excellent peak efficiency of up to 89% and features a proprietary control scheme that ensures high efficiency over a wide load current range. The ACT6308 features pin-selectable output voltages of 3.3V or 5V, or it can also be set externally to any voltage between 2V and 5V. The ACT6308 is available in a tiny SOT23-5 package. APPLICATIONS • • • • • • Hand-Held Devices One to Three Cell Battery Operated Devices PDAs Cellular Phones Digital Cameras GPS TYPICAL APPLICATION CIRCUIT Efficiency vs. Output Current VIN L 2.2µH LX OUT VOUT 3.3V 1.00 ACT6308-001 EN C1 2.2µF G FB C2 4.7µF Efficiency (%) ENABLE ACT6308 0.90 VIN = 2.4V 0.80 0.70 VIN = 1.8V 0.60 0.50 VIN = 1.5V VOUT = 3.3V FB = GND 10 100 1000 Pb-free 0.1 1.0 Output Current (mA) Innovative Products. Active Solutions. -1- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 ORDERING INFORMATION PART NUMBER ACT6308UC-T TEMPERATURE RANGE -40°C to 85°C PACKAGE PINS SOT23-5 5 PACKING METHOD TAPE & REEL TOP MARK HBCB All Active-Semi components are RoHS Compliant and with Pb-free plating unless specified differently. The term “Pb-free” means semiconductor products that are in compliance with current RoHS (Restriction of Hazardous Substances) standards. PIN CONFIGURATION FB 1 5 OUT G 2 ACT6308 4 LX EN 3 SOT23-5 PIN DESCRIPTION PIN NUMBER PIN NAME 1 2 3 4 5 FB G EN LX OUT PIN DESCRIPTION Output Voltage Selection and Feedback Input. Connect this pin to G for VOUT = 5V, to OUT for VOUT = 3.3V. Connect FB to a resistor divider to set the output voltage between 2V and 5V. See the Output Voltage Selection section for more information. Ground. Shutdown Input. Drive EN to OUT or to a logic high for normal operation, drive EN to G or to a logic low to disable the regulator. Inductor Connection. Output. ACT6308 regulates voltage at this pin. OUT also provides power to the IC. Innovative Products. Active Solutions. -2- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 ABSOLUTE MAXIMUM RATINGS PARAMETER OUT, EN to G FB, LX to G Continuous LX Current Maximum Power Dissipation (derate 5mV/°C above TA = 50°C) Junction to Ambient Thermal Resistance (θJA) Operating Junction Temperature Storage Temperature Lead Temperature (Soldering, 10 sec) VALUE -0.3 to 6 -0.3 to VOUT + 0.3 Internally Limited 0.53 190 -40 to 150 -55 to 150 300 UNIT V V A W °C/W °C °C °C : Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions for long periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN = 1.5V, VOUT = 3.3V, TA = 25°C, unless otherwise specified.) PARAMETER Minimum Operating Input Voltage Maximum Operating Input Voltage Startup Voltage Output Voltage Output Voltage Range Quiescent Current at OUT Shutdown Supply Current Startup to Normal Transition Threshold FB Feedback Voltage FB Input Current Power Switch Current Limit Power Switch On Resistance Synchronous Rectifier On Resistance LX Leakage Current Maximum Switch On-Time Minimum Switch Off-Time EN Logic Low Threshold EN Logic High Threshold EN Input Current SYMBOL VIN VIN VIN VOUT TEST CONDITIONS MIN TYP 0.6 MAX 5 UNIT V V V V V µA µA V ILOAD = 1mA FB = OUT; 60mVPP Ripple FB = G; 40mVPP Ripple External Feedback Divider 3.2 4.85 2 1 3.3 5 1.18 3.4 5.15 5 IQ ISD VFB = 1.3V EN = G 17 0.1 1.85 34 1 VFB VOUT = 2V to 5V FB = 1.3V 1.15 1.180 50 1.21 V nA ILIM RONN RONP ILX = 100mA ILX = -100mA EN = G, VLX = 0 or 3.3V tONMAX tOFFMIN VIL VIH 0.35 0.4 0.19 0.21 0.1 0.6 0.4 0.4 1 1.8 0.36 0.4 A Ω Ω µA µs µs V V 1.2 0.24 1.5 0.3 0.6 1 µA Innovative Products. Active Solutions. -3- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 TYPICAL PERFORMANCE CHARACTERISTICS (Typical Application Circuit, L = 2.2µH, C1 = 2.2µF ceramic, C2 = 4.7µF ceramic, unless otherwise specified.) Efficiency vs. Output Current 1.00 100 ACT6308-001 Efficiency vs. Output Current ACT6308-002 0.90 90 Efficiency (%) VIN = 2.4V 0.80 VIN = 3.7V Efficiency (%) 80 0.70 VIN = 1.2V VIN = 2.4V VOUT = 5V FB = GND 100 1000 70 VIN = 1.8V VIN = 1.5V VOUT = 3.3V FB = GND 10 100 1000 0.60 0.50 60 50 0.1 1.0 0.1 1.0 10 Output Current (mA) Output Current (mA) Startup Voltage vs. Constant Current Load 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0 20 40 60 80 VOUT = 3.3V 100 200 ACT6308-003 Startup Voltage vs. Constant Resistance Load 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0 20 40 60 80 VOUT = 3.3V 100 200 ACT6308-004 Startup Voltage (V) Constant Current Load (mA) Startup Voltage (V) Current Load at 3.3V (mA) Innovative Products. Active Solutions. -4- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 TYPICAL PERFORMANCE CHARACTERISTICS CONT’D (Typical Application Circuit, L = 2.2µH, C1 = 2.2µF ceramic, C2 = 4.7µF ceramic, unless otherwise specified.) Startup Voltage vs. Temperature 1.5 ACT6308-005 6.5 Maximum On-Time vs. Temperature ACT6308-006 1.0 Maximum On-Time (µS) Startup Voltage (V) 5.5 0.5 -40 -20 0 20 40 60 80 100 120 4.5 -40 -20 0 20 40 60 80 100 120 Temperature (°C) Temperature (°C) Minimum Off-Time vs. Temperature Quiescent Supply Current (µA) 1.5 25 20 ACT6308-007 Quiescent Supply Current vs. Temperature ACT6308-008 Minimum Off-Time (µS) 1.4 1.3 15 1.2 10 1.1 1.0 -40 -20 0 20 40 60 80 100 120 5 0 -40 -20 0 20 40 60 80 100 120 Temperature (°C) Temperature (°C) Innovative Products. Active Solutions. -5- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 TYPICAL PERFORMANCE CHARACTERISTICS CONT’D (Typical Application Circuit, L = 2.2µH, C1 = 2.2µF ceramic, C2 = 4.7µF ceramic, unless otherwise specified.) Light Load Operation for Low ESR COUT ACT6308-009 VOUT = 3.3V VOUT = 3.3V VIN = 1.8V ILOAD = 5mA Light Load Operation for Low ESR COUT ACT6308-010 VOUT = 5V VIN = 3.6V ILOAD = 5mA CH1 CH1 CH2 CH2 CH1: VOUT, 20.0mV/div CH2: ILX, 200mA/div TIME: 10.0µs/div CH1: VOUT, 20.0mV/div CH2: ILX, 200mA/div TIME: 20.0µs/div Medium Load Operation for Low ESR COUT ACT6308-011 VOUT = 3.3V VIN = 1.8V ILOAD = 50mA Medium Load Operation for Low ESR COUT ACT6308-012 VOUT = 5V VIN = 3.6V ILOAD = 50mA CH1 CH1 CH2 CH2 CH1: VOUT, 20.0mV/div CH2: ILX, 200mA/div TIME: 2.00µs/div CH1: VOUT, 20.0mV/div CH2: ILX, 200mA/div TIME: 2.00µs/div Heavy Load Operation for Low ESR COUT ACT6308-013 VOUT = 3.3V VIN = 1.8V ILOAD = 100mA Heavy Load Operation for Low ESR COUT ACT6308-014 VOUT = 5V VIN = 3.6V ILOAD = 110mA CH1 CH1 CH2 CH2 CH1: VOUT, 20.0mV/div CH2: ILX, 200mA/div TIME: 2.00µs/div CH1: VOUT, 20.0mV/div CH2: ILX, 200mA/div TIME: 2.00µs/div Innovative Products. Active Solutions. -6- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 FUNCTIONAL BLOCK DIAGRAM OUT LOW INPUT START UP EN REFERENCE VREF 0.3µs ONE-SHOT SET LATCH Q RESET 1.5µs ONE-SHOT DRIVER LX VREF FEEDBACK SELECT FB CURRENT LIMIT COMPARATOR FUNCTIONAL DESCRIPTION As seen in the Functional Block Diagram, the ACT6308 comprises a reference, low input startup circuitry, feedback select, error comparator, control logic and timers, internal power MOSFETs and current comparators. Light Load Operation Under light load conditions, the IC automatically enters a power-saving mode by extending the OFF time. This reduces switching losses and allows the ACT6308 to maintain high efficiency across a very wide load range. Main Control Loop The ACT6308 control architecture utilizes a series of one-shot and current sense circuits to regulate the output voltage with a very low quiescent supply current of just 17µA. An ON cycle begins when FB falls below the ACT6308’s internal reference voltage. During an ON cycle, the N-channel power switch is turned on to connect the LX node to ground, transferring energy from input supply to the inductor. The ON cycle persists or the 0.4A current limit is reached. When either of these conditions occurs, the N-channel power switch turns off and the OFF cycle begins. During the OFF cycle, the energy stored in the inductor is released into the output capacitor and load through the synchronous rectifier. Once the 0.3µs minimum OFF time expires, another ON cycle begins when the FB voltage drops below the reference voltage. Low Voltage Startup The ACT6308 uses proprietary start-up circuitry that allows it to achieve very low voltage startup down to 1V. The ACT6308 remains in low voltage startup mode until VOUT exceeds 1.85V. The ACT6308 cannot support its full rated load current when operating in low-voltage startup mode. Care should be taken to minimize load current during startup. Shutdown In shutdown mode, all internal circuits including the power switch and the synchronous rectifier are disabled, reducing quiescent supply current to less than 1µA. Note that in shutdown mode, a DC path from the input supply to the output still exists due to the body diode of the synchronous rectifier. Innovative Products. Active Solutions. -7- Copyright © 2008 Active-Semi, Inc. – + + – + ERROR COMPARATOR G – www.active-semi.com ACT6308 Rev PrB, 20-Feb-08 APPLICATIONS INFORMATION Output Voltage Selection The ACT6308 provides fixed output voltage options of 3.3V or 5V, or the output voltage may be adjusted over a 2V to 5V range by connecting an external resistive voltage divider. When Output Voltage is set by external resistive voltage divider, add a 47pF to 150pFcapacitor as feed forward capacitor (CFF) as shown in Figure 1. Table 1: Output Voltage Programming FB = OUT FB = G FB connect to resistive divider VOUT = 3.3V VOUT = 5V VOUT = 1.18V (1 + RFB1/RFB2) output current. Choose inductors with low series resistance to obtain the highest efficiency. Board Layout To reduce noise and increase efficiency, high current traces should be wide and direct, and an extended ground plane should be used. Switching current paths should be laid out as tightly as possible, with the inductor and input and output capacitors located close to the IC in order to reduce electromagnetic radiation. If an external resistor divider is used, place the resistors very close to the FB and G pins, and keep them away from the high switching current paths. Figure 1: Output Voltage Setting VOUT OUT CFF RFB1 ACT6308 FB RFB2 Output Capacitor Selection A minimum value of output capacitance is required to maintain loop stability and normal operation of the IC. The output capacitor value should be in the range of 2.2µF to 100µF. To obtain small output ripple, use a large capacitor with low ESR. Ceramic capacitors should be used for highest performance. If a tantalum capacitor is used, choose only low ESR types and a smaller low ESR capacitor of about 1µF can be connected in parallel to filter high frequency noise. Inductor Selection For most applications, the inductor value should be in the range of 1.5µH to 22µH. Smaller inductors provide faster load transient response and have a smaller physical size, but they also result in higher ripple current and reduce the maximum available Innovative Products. Active Solutions. -8www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 PACKAGE OUTLINE SOT23-5 PACKAGE OUTLINE AND DIMENSIONS D b L1 θ 0.2 SYMBOL A A1 DIMENSION IN MILLIMETERS MIN 1.050 0.000 1.050 0.300 0.100 2.820 1.500 2.650 DIMENSION IN INCHES MIN 0.041 0.000 0.041 0.012 0.004 0.111 0.059 0.104 MAX 1.250 0.100 1.150 0.400 0.200 3.020 1.700 2.950 MAX 0.049 0.004 0.045 0.016 0.008 0.119 0.067 0.116 E1 E A2 b c L e e1 c D E E1 e 0.950 TYP 1.800 2.000 0.037 TYP 0.071 0.079 A1 A2 A e1 L L1 θ 0.700 REF 0.300 0° 0.600 8° 0.028 REF 0.012 0° 0.024 8° Active-Semi, Inc. reserves the right to modify the circuitry or specifications without notice. Users should evaluate each product to make sure that it is suitable for their applications. Active-Semi products are not intended or authorized for use as critical components in life-support devices or systems. Active-Semi, Inc. does not assume any liability arising out of the use of any product or circuit described in this datasheet, nor does it convey any patent license. Active-Semi and its logo are trademarks of Active-Semi, Inc. For more information on this and other products, contact sales@active-semi.com or visit http://www.active-semi.com. For other inquiries, please send to: 1270 Oakmead Parkway, Suite 310, Sunnyvale, California 94085-4044, USA Innovative Products. Active Solutions. -9- www.active-semi.com Copyright © 2008 Active-Semi, Inc.